├── .github
    └── ISSUE_TEMPLATE
    │   └── new-cheat-sheet-request.md
├── ada.md
├── adb.md
├── alias.md
├── android-versions.md
├── angular.md
├── arrow-functions.md
├── assembly.md
├── async-http-client.md
├── axios.md
├── azure.md
├── bash.md
├── bcryptjs.md
├── c.md
├── cat.md
├── cd.md
├── challenges-code-preloads.md
├── chmod.md
├── cksum.md
├── cmp.md
├── comm.md
├── commonlisp.md
├── cp.md
├── cpp.md
├── cron.md
├── crontab.md
├── csharp.md
├── css.md
├── curl.md
├── cut.md
├── d.md
├── dart.md
├── dns.md
├── docker.md
├── dockerfile.md
├── dotenv.md
├── echo.md
├── ejs-embedded-javascript-templates.md
├── elixir.md
├── erlang.md
├── es2csv.md
├── express.md
├── figma.md
├── find.md
├── flutter.md
├── fortran.md
├── fsharp.md
├── git.md
├── go.md
├── google-analytics.md
├── google-nexus-screen-resolutions.md
├── google-pixel-screen-resolutions.md
├── grep.md
├── groovy-http-calls.md
├── groovy.md
├── gson.md
├── haskell.md
├── head.md
├── heroku.md
├── homebrew.md
├── html.md
├── http-staus-codes.md
├── iphone-screen-resolutions.md
├── java-primitive-data-types.md
├── java-strings.md
├── java-versions.md
├── java.md
├── javascript-fetch.md
├── javascript-versions.md
├── javascript.md
├── jest.md
├── jquery.md
├── jshell.md
├── jsonata.md
├── jsoup.md
├── kill.md
├── kubernetes.md
├── link.md
├── linux.md
├── lodash.md
├── ls.md
├── lua.md
├── make.md
├── man.md
├── markdown.md
├── maven.md
├── mkdir.md
├── mongodb.md
├── mv.md
├── mysql.md
├── netlify.md
├── nodejs.md
├── nodemon.md
├── ocaml.md
├── okhttp.md
├── onecompiler-apis.md
├── onecompiler-enterprise-apis.md
├── perl.md
├── php.md
├── pm2.md
├── prop-types.md
├── ps.md
├── pwd.md
├── python.md
├── r.md
├── racket.md
├── react-helmet.md
├── react-prerequisites.md
├── reactjs.md
├── redis.md
├── request.md
├── rm.md
├── rmdir.md
├── ruby.md
├── rust.md
├── scala.md
├── scp.md
├── search-engins.md
├── solidity.md
├── sql.md
├── super-csv.md
├── tail.md
├── tar-gz.md
├── tcl.md
├── typescript.md
├── underscore.md
├── vb.md
├── vuejs.md
├── vyper.md
├── wc.md
├── windows-shortcuts.md
└── yaml.md


/.github/ISSUE_TEMPLATE/new-cheat-sheet-request.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | name: New Cheat Sheet Request
 3 | about: Suggest a missing Cheat Sheet
 4 | title: New Cheat Sheet Request - [Cheat Sheet Title]
 5 | labels: New Cheat Sheet
 6 | assignees: ''
 7 | 
 8 | ---
 9 | 
10 | Add more details about the requested Cheat Sheet like reference links etc.,
11 | 


--------------------------------------------------------------------------------
/ada.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Ada
  3 | description: Ada Programming language cheatsheet contains useful code syntax with examples which is handy while coding.
  4 | created: 2020-06-24
  5 | updated: 2024-02-05
  6 | ---
  7 | 
  8 | ## Data types
  9 | 
 10 | * Strongly typed
 11 | 
 12 | | Types | Data-type|
 13 | |----|----|
 14 | |Basic | Integer, Character, Float, Long_Float, Short_Integer, Long_Integer, etc |
 15 | |Pointer | access |
 16 | |Composite | array, String |
 17 | |User Defined Data Type | record, enumeration, tagged type, variant record, range types, etc. |
 18 | 
 19 | 
 20 | ### Naming convention
 21 | * First character in identifier is a letter, then letters (both uppercase and lowercase letters), digits and underscore(`_`).
 22 | * Case insensitive
 23 | 
 24 | ## Arrays
 25 | 
 26 | ```ada
 27 | array-name : array (Fist..Last) of element-type; -- one-dimensional Array
 28 | array-name : array (Fist1..Last1, First2..Last2) of element-type; -- two-dimensional Array
 29 | ```
 30 | ## String
 31 | 
 32 | It is an array of Character.
 33 | 
 34 | ```ada
 35 | My_String := String := "abcde"; -- string declaration
 36 | ```
 37 | 
 38 | ## Literals or Constants
 39 | |Literal | Example|
 40 | |----|----|
 41 | |Integer Literal- decimal|255|
 42 | |Integer Literal- octal|8#377#|
 43 | |Integer Literal- hexadecimal|16#FF#|
 44 | |Float point Literal|53.0, 79e-6|
 45 | |Character literals| 'a', '1'|
 46 | |String literals| "OneCompiler", "Foo"|
 47 | |Boolean literals| True, False|
 48 | 
 49 | ### Special characters
 50 | Special characters are defined as constans in `ASCII` or `Ada.Characters.Latin_1` package.
 51 | |Constant| Description|
 52 | |----|----|
 53 | |LF	| New line|
 54 | |CR	| Carriage Return|
 55 | |HT	| Horizontal tab|
 56 | |VT	| Vertical tab|
 57 | |NUL | Null character|
 58 | 
 59 | ## Operators
 60 | 
 61 | | Operator type | Description|
 62 | |----|-----|
 63 | | Arithmetic Operator|+ , - , * , / , `**` (exponentiation)|
 64 | | Relational Operator| < , > , <= , >=, /= , =|
 65 | | Logical Operator| `and` , `or`, `xor`, `not` |
 66 | | Assignment Operator| := |
 67 | | If expression| (if a then b else c) |
 68 | 
 69 | ## Sample program
 70 | 
 71 | ```ada
 72 | with Ada.Text_IO; use Ada.Text_IO;
 73 | procedure Hello is
 74 | begin
 75 |    Put_Line ("Hello, World!");
 76 | end Hello;
 77 | ```
 78 | * `Ada.Text_IO` : package that contains routines for I/O of text.
 79 | * `with` : tells compiler that the package will be used.
 80 | * `use` : tells compiler that the package should be automatically searched and allows access to routines without using the fully qualified name.
 81 | * `procedure` : used to declare a procedure named Hello here.
 82 | * `Put_Line` : is a procedure for string output. 
 83 | * `--` : comment.
 84 | 
 85 | ## Variables
 86 | 
 87 | ```ada
 88 | varName : DataType := value;
 89 | ```
 90 | ## Constants
 91 | ```ada
 92 | varName : constant DataType := value;
 93 | ```
 94 | ## Conditional Statements
 95 | 
 96 | ### 1. If-else
 97 | ```ada
 98 | if conditional-expr then 
 99 |     --code if above statement is true
100 | elseif conditional-expr then 
101 |     --code if above statement is true
102 | end if;
103 | ```
104 | 
105 | ### 2. Case
106 | ```ada
107 | case expr is 
108 |     when expr => --code
109 |     when expr => --code
110 |     ...
111 |     when others => --code;
112 | end case;
113 | ```
114 | ## Loops
115 | 
116 | ### 1. Infinite loop:
117 | 
118 | This is the simplest loop
119 | 
120 | ```ada
121 |    Index := 1; --initialization
122 |    loop                            
123 |       --code
124 |       exit when Index = n;
125 |    end loop;
126 | ```
127 | ### 2. while loop
128 | 
129 | ```ada
130 |    Count := 1;    --initialization
131 |    while Count < n loop  
132 |       --code
133 |    end loop;
134 | ```
135 | 
136 | ### 3. for loop
137 | 
138 | ```ada
139 | for Index in 1..n loop          
140 |    --code
141 | end loop;
142 | ```
143 | ## Sub programs
144 | 
145 | Functions and procedures are collectively called as sub-programs.
146 | 
147 | ### Syntax for procedures
148 | 
149 | ```ada
150 | procedure proc_name
151 |    (X : in Integer ; Y : out Integer ; Z : in out Integer ) is
152 | begin
153 |    X := 10; −− it's an Error as you can’t modify an in parameter.
154 |    Y := X; −− can modify Y as it's an out parameter.
155 |    Z := Z + 1; −− can read and write as it's an in out parameter.
156 | end proc_name;
157 | ```
158 | ### Syntax for functions
159 | 
160 | ```ada
161 | function function_name(parameter : parameter_type) return value is
162 | begin
163 |    --code
164 | end function_name;
165 | ```
166 | 


--------------------------------------------------------------------------------
/adb.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: ADB (Android Debug Bridge)
 3 | description: Android Debug Bridge command-line tool helps us to interact with connected Android device/ Emulator. We can install, debug apps using ADB
 4 | created: 2019-06-17
 5 | updated: 2023-10-12
 6 | ---
 7 | 
 8 | ## Selecting Device
 9 | 
10 | |Command|Description|
11 | |---|---|
12 | |`adb devices`|This command is used to retrieve all devices by serial number|
13 | |`adb devices -l`|List of devices by product/model|
14 | |`adb -s <device> <command>`|Use the -s option followed by a device name to select on which device the adb command should run. The -s options should be first in line, before the command.|
15 | 
16 | ## App installation & uninstallation
17 | |Command|Description|
18 | |---|---|
19 | |`adb install <apk>`|Install app|
20 | |`adb shell pm install <path_from_phone>`|Install app from phone path|
21 | |`adb shell pm install -r <path_from_phone>`|Reinstall app from phone path|
22 | |`adb uninstall <com.test.package.name>`|Remove the app|
23 | 
24 | ## App info 
25 | |Command|Description|
26 | |---|---|
27 | |`adb shell pm list packages`|List package names|
28 | |`adb shell pm list packages -f`|as above + path tp APks|
29 | |`adb shell pm -3`| only third party packages|
30 | |`adb shell pm -s`|only system packages|
31 | |`adb shell pm -u`|also uninstalled packages|
32 | |`adb shell dumpsys package packages`|List info on all apps|
33 | |`adb shell pm dump name`|List info on one package|
34 | |`adb shell pm path package`|path to the APK file|
35 | 
36 | 
37 | ## Permissions
38 | |Command|Description|
39 | |---|---|
40 | |`adb shell pm permission groups`|Permission groups definitions|
41 | |`adb shell pm list permissions -g -f`|List permissions details|
42 | 
43 | 
44 | ## Common actions
45 | |Command|Description|
46 | |---|---|
47 | |`am start -a android.intent.action.VIEW -d URL`|To open the URL|
48 | 
49 | 
50 | ## Miscellaneous
51 | |Command|Description|
52 | |---|---|
53 | |`screencap -p .png`|Screenshot (saved on device)|
54 | |`screenrecord .mp4`|Screen capture (path on device)|
55 | 
56 | ## Copy files to/from a device
57 | |Command|Description|
58 | |---|---|
59 | |`adb pull <remote> <local>`|To copy a file or directory and its sub-directories from the device|
60 | |`adb push <local> <remote>`|To copy a file or directory and its sub-directories to the device|
61 | 
62 | Replace local and remote with the paths to the target files/directory on your development machine (local) and on the device (remote).For example:<br />
63 | adb push foo.txt /sdcard/foo.txt
64 | 
65 | ## ADB daemon
66 | |Command|Description|
67 | |---|---|
68 | |`adb kill-server`|Kill the server if it is running|
69 | |`adb start-server`|Ensure that there is a server running|
70 | |`adb root`|Restarts the adbd with root permissions|
71 | 
72 | ## Steps to pair and connect to adb over wifi [Android 11+]
73 | 1. On device, go to developer settings and enable wireless debugging
74 | 1. Type `adb pair [ip]:[port]` and replace [ip] and [port] with the ip and port shown on the device
75 | 2. Then you will be asked for a pairing code.Enter that as shown on the device.
76 | 3. Now to connect type `adb connect [ip]:[port]` and replace [ip] and [port] with the the ip and port seen on the Wireless debugging page after closing the pairing dialog.
77 | 


--------------------------------------------------------------------------------
/alias.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: alias Linux Command
 3 | description: alias command is used to create our own commands (command shortcuts) so that we don't have to remember/ type repeatedly used/ lengthy commands.  
 4 | created: 2019-08-23
 5 | updated: 2019-08-23
 6 | ---
 7 | 
 8 | `alias` command is used to create our own commands (command shortcuts) so that we don't have to remember/ type repeatedly used/ lengthy commands.
 9 | 
10 | # Creating an alias 
11 | Following is the syntax for creating an `alias`
12 | 
13 | ```sh
14 | alias name=value
15 | ```
16 | where the `name` is the new name you want to assign and `value` is the actual command.
17 | Lets take a realtime usecase so that we can understand easily. 
18 | We will type `ls -al` frequently to list all files in a directory. Lets assign an alias `files` to the command so that you can simply type `files` instead typing `ls -al`. Following command creats the alias with name `files` for `ls- al`
19 | 
20 | ```sh
21 | alias files='ls -al'
22 | ```
23 | 
24 | After runnng the about command we can simply type `files` to list all files & directories, instead typing `ls -al`
25 | 
26 | # Listing all created aliases 
27 | 
28 | Following command lists all created aliases
29 | 
30 | ```sh
31 | alias -p
32 | ```
33 | ### Example 
34 | 
35 | ```sh
36 | $ alias -p
37 | alias files='ls -al'
38 | ```
39 | 
40 | # Deleting an alias
41 | We can delete an alias with name using following command
42 | 
43 | ```sh
44 | unalias <alians_name>
45 | ```
46 | 
47 | # Deleting all aliases
48 | Following command removes all aliases that are created 
49 | 
50 | ```sh
51 | unalias -a
52 | ```


--------------------------------------------------------------------------------
/android-versions.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Android Versions
 3 | description: Android Versions with release years and features added
 4 | created: 2019-08-19
 5 | updated: 2022-10-04
 6 | color: #f4de50
 7 | ---
 8 | 
 9 | | Version | Year | Version Name (s) | Features added |
10 | |--------|--------|--------|--------|
11 | |1.0|September 23, 2008|Astroid||
12 | |1.1|February 9, 2009|Petit Four|Longer in-call screen timeout, Ability to save attachments in messages, marquee in system layouts|
13 | |1.5|April 27, 2009	|Cupcake|Video recording and playback in MPEG-4 and 3GP formats, Animated screen transitions, Ability to upload videos to YouTube|
14 | |1.6|September 15, 2009|Donut|Voice and text entry search, multiple photos for deletion, WVGA screen resolutions|
15 | |2.0|October 26, 2009|Eclair|Contacts photo and select to call, SMS, or email the person, Bluetooth 2.1 support, new camera features|
16 | |2.2|May 20, 2010|Froyo|Speed, memory, and performance optimizations, USB tethering and Wi-Fi hotspot functionality,  zoom gesture|
17 | |2.3|December 6, 2010|Gingerbread|native code development, New Download Manager, Support for multiple cameras on the device|
18 | |3.0|February 22, 2011|Honeycomb|holographic user interface, Added System Bar, Simplified multitasking|
19 | |4.0|October 18, 2011|Ice Cream Sandwich|Ability to access applications directly from lock screen, Face Unlock, Built-in photo editor|
20 | |4.1|July 9, 2012|Jelly Bean|Expandable notifications, Bluetooth data transfer for Android Beam, USB audio|
21 | |4.4|October 31, 2013|KitKat|Wireless printing capability[, Native infrared blaster API |
22 | |5.0|November 12, 2014|Lollipop|Project Volta, for battery life improvements, Smart lock feature |
23 | |6.0|October 5, 2015|Marshmallow|USB-C support, 4K display mode for apps, multi-window feature |
24 | |7.0|August 22, 2016|Nougat|Daydream virtual reality platform (VR interface), Vulkan 3D rendering API |
25 | |8.0|August 21, 2017|Oreo|Notification improvements, Multi-display support, Wi-Fi Assistant |
26 | |9.0|August 6, 2018|Pie|Rounded corners across the UI, Android Dashboard, Redesigned volume slider |
27 | |10|September 3, 2019|Q|New safeguards to protect user privacy that need to support in our app. |
28 | |11|September 8, 2020|Red Velvet Cake|Conversations, bubbles, device and media controls, 5G, biometric and more.|
29 | |12|October 4, 2021|Snow Cone|A new system UI that's expressive, dynamic, and personal. Extend your apps with redesigned widgets, AppSearch, Game Mode, and new codecs. |
30 | |13|August 15,2022|Tiramisu|Build for user privacy with photo picker and notification permission. Improve productivity with themed app icons, per-app languages, and clipboard preview. |
31 | 


--------------------------------------------------------------------------------
/angular.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Angular CheatSheet
  3 | description: Angular cheatsheet contains basics of angular binding & angular CLI.
  4 | created: 2022-10-03
  5 | updated: 2022-10-03
  6 | ---
  7 | 
  8 | # Angular Cheatsheet
  9 | 
 10 | Angular is an application-design framework and development platform for creating efficient and sophisticated single-page apps.
 11 | 
 12 | #### Angular Binding:
 13 | 
 14 |  - One Way Binding:
 15 | 	```
 16 | 	<p>title</p>
 17 | 	//No changes were reflected back to the variable.
 18 | 	```
 19 | - Two Way Binding
 20 | 	```
 21 | 	<input [(ngMo­del­)]=­"­student.F­ir­stN­ame­">
 22 | 	//Changes were reflected back to the variable
 23 | 	```
 24 | - Property Binding
 25 | 	```
 26 | 	<img [src]=­"­student.profilePicUrl">
 27 | 	```
 28 | - Attribute Binding
 29 | 	```
 30 | 	<button [attr.a­ri­a-l­abe­l]=­"­ok">­Ok<­/bu­tto­n>
 31 | 	```
 32 | - Class Binding
 33 | 	```
 34 | 	<div [class.Focused]="isFocused">S­ele­cte­d</­div>
 35 | 	```
 36 | - ngClass
 37 | 	```
 38 | 	<div [ngClass]="assignClasses()">
 39 | 	  <h1>{{student.FirstName}}</h1>
 40 | 	</div>
 41 | 	```
 42 | - Style Binding
 43 | 	```
 44 | 	<p [style.co­lor­]="i­sSe­lected ? 'green' : 'red'">Option {{i}}</p>
 45 | 	```
 46 |  - ngStyle
 47 | 	 ```
 48 | 	<div [ngStyle]="setStyles()">
 49 | 	  {{student.name}}
 50 | 	</div>
 51 | 	```
 52 | 
 53 | - Component Binding
 54 | 	```
 55 | 	<student-details [student]="currStudent"></student-details>
 56 | 	```
 57 | - Directive Binding
 58 | 	```
 59 | 	<div [ngClass] = "­{se­lected: isSele­cte­d}">­Student<­/di­v>
 60 | 	```
 61 | - Event Binding
 62 | 	```
 63 | 	<button (click­)="test()">­Test</­but­ton>
 64 | 	```
 65 | - $event
 66 | 	```
 67 | 	<input [value]="student.name"
 68 | 	 (input)="student.name=$event.target.value">
 69 | 	 ```
 70 | 	 
 71 | #### Angular Lifecycle Hooks:
 72 | - ngOnInit()
 73 | 	```
 74 | 	It get invoked when angular initialize component or directive.
 75 | 	```
 76 | - ngOnChanges()
 77 | 	```
 78 | 	It get invoked when angular sets data bound input property i.e. @Input().
 79 | 	```
 80 | - ngDoCheck()
 81 | 	```
 82 | 	It get invoked for every changes.
 83 | 	```
 84 | - ngAfterContentInit()
 85 | 	```
 86 | 	It get invoked after angular project content in its view.
 87 | 	```
 88 | - ngAfterContentChecked()
 89 | 	```
 90 | 	It get invoked after angular checks the binding of content into view.
 91 | 	```
 92 | - ngAfterViewInit()
 93 | 	```
 94 | 	It get invoked after angular create component view.
 95 | 	```
 96 | - ngAfterViewChecked()
 97 | 	```
 98 | 	It get invoked after angular checks the binding of component view.
 99 | 	```
100 | - ngOnDestroy()
101 | 	```
102 | 	It get invoked before angular destroy component or directives.
103 | 	```
104 | 
105 | #### Angular CLI commands:
106 | 
107 | - To create a *new project*
108 | 	```
109 | 	ng new project-name
110 | 	```
111 | 	
112 | - To generate a *component*
113 | 	```
114 | 	ng g component <name>
115 | 	```
116 | 
117 | - To generate *directive*
118 | 	```
119 | 	ng g directive <name>
120 | 	```
121 | 
122 | - To generate *pipe*
123 | 	```
124 | 	ng g pipe <name>
125 | 	```
126 | 
127 | - To generate *service*
128 | 	```
129 | 	ng g service <name>
130 | 	```
131 | 
132 | - To generate *class*
133 | 	```
134 | 	ng g class <name>
135 | 	```
136 | 
137 | - To g *interface*
138 | 	```
139 | 	ng g interface <name>
140 | 	```
141 | 
142 | - *Run application* in local server
143 | 	```
144 | 	ng serve
145 | 	```
146 | - Create a build and change environment
147 | 	```
148 | 	ng build [--e=<name>]
149 | 	```
150 | 
151 | - *Testing* your application
152 | 	```
153 | 	ng test | e2e
154 | 	```
155 | 	
156 | - universal command // This command is used to pass this schematic to the "run" command to set up server-side rendering for an app
157 | 	```
158 |        ng generate universal [options]  
159 |        ng g universal [options]  
160 | 	```
161 | 	AND [options]
162 | 	--defaults=true|false: When true, it disables interactive input prompts for options with a default.
163 | 
164 |         --dryRun=true|false: When true, it runs through and reports activity without writing out results.
165 | 


--------------------------------------------------------------------------------
/arrow-functions.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Arrow Functions in Javascript
 3 | description: Arrow Function usage in Javascript
 4 | created: 2019-10-15
 5 | updated: 2019-10-23
 6 | ---
 7 | 
 8 | Arrow functions help developers in writing more concise code, and were introduced in ES6.
 9 | Arrow functions can be written in multiple ways. Below are couple of ways to use arrow functions, although, they can be written in many other ways as well:
10 | 
11 | ## 1. With no argument
12 | 
13 | ### Syntax
14 | 
15 | ```javascript
16 | () => expression
17 | ```
18 | 
19 | ### Example
20 | 
21 | ```javascript
22 | const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
23 | 
24 | const squaresOfEvenNumbers = numbers.filter(ele => ele % 2 == 0)
25 |                                     .map(ele => ele ** 2);
26 | 
27 | console.log(squaresOfEvenNumbers);
28 | ```
29 | 
30 | ## 2. With Multiple arguments
31 | 
32 | ### Syntax
33 | 
34 | ```javascript    
35 | (a1,b1,c1) => expression
36 | ```
37 | 
38 | ### Example
39 | ```javascript    
40 | let sum= (a,b,c) => {
41 |     return a+b+c;
42 | }
43 | console.log(sum(10,20,30));
44 | ```
45 | 
46 | ## Benefits:
47 | 
48 | 1. Shorter syntax
49 | 2. Bind this lexically
50 | 3. Simplify function scoping
51 | 


--------------------------------------------------------------------------------
/assembly.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Assembly language 
  3 | description: Assembly language cheatsheet gives you a quick reference to code syntax with examples makes it handy while coding.
  4 | created: 2020-07-06
  5 | updated: 2020-07-06
  6 | ---
  7 | 
  8 | ## Sample program
  9 | ```c
 10 | section .data
 11 | 	hello:     db 'Hello world!',10    ; 'Hello world!' plus a linefeed character
 12 | 	helloLen:  equ $-hello             ; Length of the 'Hello world!' string
 13 | 
 14 | section .text
 15 | 	global _start
 16 | 
 17 | _start:
 18 | 	mov eax,4            ; The system call for write (sys_write)
 19 | 	mov ebx,1            ; File descriptor 1 - standard output
 20 | 	mov ecx,hello        ; Put the offset of hello in ecx
 21 | 	mov edx,helloLen     ; helloLen is a constant, so we don't need to say
 22 | 	                     ;  mov edx,[helloLen] to get it's actual value
 23 | 	int 80h              ; Call the kernel
 24 | 	mov eax,1            ; The system call for exit (sys_exit)
 25 | 	mov ebx,0            ; Exit with return "code" of 0 (no error)
 26 | 	int 80h;
 27 | ```
 28 | Assembly language usually consists of three sections, 
 29 | 
 30 | 1. Data section
 31 | 
 32 |     To initialize variables and constants, buffer size these values doesn't change at runtime. 
 33 | 
 34 | 2. bss section
 35 | 
 36 |     To declare variables
 37 | 
 38 | 3. text section
 39 | 
 40 |     `_start` specifies the starting of this section where the actually code is written. 
 41 | 
 42 | ## Variables
 43 | 
 44 | There are various define directives to allocate space for variables for both initialized and uninitialized data.
 45 | 
 46 | ### 1.  To allocate storage space to Initialized data
 47 | 
 48 | ```c
 49 | variable-name    define-directive    initial-value 
 50 | ```
 51 | 
 52 | |Define Directive| Description| Allocated Space|
 53 | |-----|----|----|
 54 | |DB| Define Byte| 1 byte|
 55 | |DW| Define Word| 2 bytes|
 56 | |DD| Define Doubleword | 4 bytes|
 57 | |DQ| Define Quadword | 8 bytes|
 58 | |DT| Define Ten Bytes | 10 bytes|
 59 | 
 60 | 
 61 | ### 2.  To allocate storage space to un-initialized data
 62 | 
 63 | |Define Directive| Description|
 64 | |-----|----|
 65 | |RESB |	Reserve a Byte|
 66 | |RESW | Reserve a Word|
 67 | |RESD |	Reserve a Doubleword|
 68 | |RESQ |	Reserve a Quadword|
 69 | |REST |	Reserve a Ten Bytes|
 70 | 
 71 | ## Constants
 72 | 
 73 | Constants can be defined using 
 74 | 
 75 | ### 1. equ
 76 | 
 77 |  * To define numeric constants
 78 | 
 79 | ```
 80 | CONSTANT_NAME EQU regular-exp or value
 81 | ```
 82 | ### 2. %assign
 83 | 
 84 |  * To define numeric constants.
 85 | 
 86 |  ```
 87 |  %assign constant_name value
 88 |  ```
 89 | 
 90 | ### 3. %define
 91 | * To define numeric or string constants.
 92 | 
 93 | ```
 94 | %define constant_name value
 95 | ```
 96 | 
 97 | ## Loops
 98 | 
 99 | Loops are used to iterate a set of statements for a specific number of times.
100 | 
101 | ```
102 | mov ECX,n
103 | L1:
104 | ;<loop body>
105 | loop L1
106 | ```
107 | where n specifies the no of times loops should iterate.
108 | 
109 | ## Procedures
110 | 
111 | ```
112 | procedure_name:
113 |    ;procedure body
114 |    ret
115 | ```
116 | 


--------------------------------------------------------------------------------
/async-http-client.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Async Http Client (Java Library)
  3 | description: Async Http Client is a high performant Http and WebSocket client library for Java. Async Http Client built on top of Netty and it provides asyc APIs for executing http requests.
  4 | created: 2019-06-25
  5 | updated: 2019-06-25
  6 | color: #0984e3
  7 | ---
  8 | 
  9 | 
 10 | Async Http Client is a high performant Http and WebSocket client library for Java. Async Http Client built on top of Netty and it provides asyc APIs for executing http requests.
 11 | 
 12 | ## Installation
 13 | #### Maven
 14 | ```xml
 15 | <!-- https://mvnrepository.com/artifact/org.asynchttpclient/async-http-client -->
 16 | <dependency>
 17 |     <groupId>org.asynchttpclient</groupId>
 18 |     <artifactId>async-http-client</artifactId>
 19 |     <version>2.10.0</version>
 20 | </dependency>
 21 | ```
 22 | #### Gradle
 23 | ```groovy
 24 | // https://mvnrepository.com/artifact/org.asynchttpclient/async-http-client
 25 | compile group: 'org.asynchttpclient', name: 'async-http-client', version: '2.10.0'
 26 | ```
 27 | 
 28 | ## GET example
 29 | 
 30 | ```java
 31 | import static org.asynchttpclient.Dsl.asyncHttpClient;
 32 | 
 33 | import org.asynchttpclient.AsyncHttpClient;
 34 | import org.asynchttpclient.ListenableFuture;
 35 | import org.asynchttpclient.Response;
 36 | 
 37 | public class AsyncHttpGetExample {
 38 |     public static void main(String[] args) {
 39 | 
 40 |         AsyncHttpClient asyncHttpClient = asyncHttpClient();
 41 | 
 42 |         try {
 43 |             ListenableFuture<Response> responseFuture = asyncHttpClient.prepareGet("https://httpbin.org/get").execute();
 44 |             Response res = responseFuture.get(); // or handle asynchronously
 45 |             System.out.println(res.getResponseBody());
 46 |         } catch (Exception e) {
 47 |             e.printStackTrace();
 48 |         } finally {
 49 |             try {
 50 |                 asyncHttpClient.close();
 51 |             } catch (Exception closingException) {
 52 |                 // Ignore
 53 |             }
 54 |         }
 55 | 
 56 |     }
 57 | }
 58 | ```
 59 | 
 60 | ## POST Example
 61 | 
 62 | ```java
 63 | import static org.asynchttpclient.Dsl.asyncHttpClient;
 64 | import static org.asynchttpclient.Dsl.post;
 65 | 
 66 | import java.util.concurrent.Future;
 67 | 
 68 | import org.asynchttpclient.AsyncHttpClient;
 69 | import org.asynchttpclient.Request;
 70 | import org.asynchttpclient.Response;
 71 | 
 72 | public class AsyncHttpPostExample {
 73 |     public static void main(String[] args) {
 74 | 
 75 |         AsyncHttpClient asyncHttpClient = asyncHttpClient();
 76 |         try {
 77 |             String body = "{\n" + 
 78 |                     "    \"foo\" : \"bar\"\n" + 
 79 |                     "}";
 80 |             Request request = post("https://httpbin.org/post").setBody(body).build();
 81 |             Future<Response> responseFuture = asyncHttpClient.executeRequest(request);
 82 |             Response res = responseFuture.get(); // or handle asynchronously
 83 |             System.out.println(res.getResponseBody());
 84 |         } catch (Exception e) {
 85 |             e.printStackTrace();
 86 |         } finally {
 87 |             try {
 88 |                 asyncHttpClient.close();
 89 |             } catch (Exception closingException) {
 90 |                 // Ignore
 91 |             }
 92 |         }
 93 | 
 94 |     }
 95 | }
 96 | 
 97 | ```
 98 | 
 99 | 
100 | 


--------------------------------------------------------------------------------
/axios.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: axios (Javascript Library)
 3 | description: Axios is promise based HTTP client for both clientside and server side
 4 | created: 2019-06-21
 5 | updated: 2019-06-21
 6 | ---
 7 | 
 8 | 
 9 | Axios is promise based HTTP client for both clientside and server side
10 | 
11 | ## Installation
12 | 
13 | ```sh
14 | npm install axios
15 | ```
16 | 
17 | ## Example GET request
18 | 
19 | ```javascript
20 | const axios = require('axios');
21 | 
22 | axios.get('https://httpbin.org/get')
23 |         .then(function (response) {
24 |             // handle success
25 |             console.log(response);
26 |         })
27 |         .catch(function (error) {
28 |             // handle error
29 |             console.log(error);
30 |         })
31 |         .finally(function () {
32 |             // always executed
33 |         });
34 | ```
35 | 
36 | ## Example GET request (using async/ await)
37 | 
38 | ```javascript
39 | const response = await axios.get('https://httpbin.org/get');
40 | console.log(response);
41 | 
42 | ```
43 | 
44 | ## Example POST request
45 | ```javascript
46 | axios.post('https://httpbin.org/post', {
47 |             foo: "bar"
48 |         })
49 |         .then(function (response) {
50 |             console.log(response);
51 |         })
52 |         .catch(function (error) {
53 |             console.log(error);
54 |         });
55 | ```


--------------------------------------------------------------------------------
/bcryptjs.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Bcrpyt
 3 | description: The bcrypt hashing function allows us to build a password security platform.
 4 | created: 2021-10-15
 5 | updated: 2021-10-15
 6 | ---
 7 | 
 8 | 
 9 | Bcrypt is among the most popular and safest, one-way hashing functions for passwords.
10 | 
11 | ## Installation
12 | 
13 | ```sh
14 | npm install bcryptjs
15 | ```
16 | 
17 | ## Usage - Sync
18 | 
19 | **To hash a password:**
20 | 
21 | ```javascript
22 | var bcrypt = require('bcryptjs');
23 | var salt = bcrypt.genSaltSync(10);
24 | var hash = bcrypt.hashSync("B4c0/\/", salt);
25 | // Store hash in your password DB.
26 | ```
27 | 
28 | **To check a password:**
29 | ```javascript
30 | // Load hash from your password DB.
31 | bcrypt.compareSync("B4c0/\/", hash); // true
32 | bcrypt.compareSync("not_bacon", hash); // false
33 | ```
34 | 
35 | **Auto-gen a salt and hash:**
36 | ```javascript
37 | var hash = bcrypt.hashSync('bacon', 8);
38 | ```
39 | 
40 | ## Usage - Async
41 | 
42 | **To hash a password:**
43 | ```javascript
44 | var bcrypt = require('bcryptjs');
45 | bcrypt.genSalt(10, function(err, salt) {
46 |     bcrypt.hash("B4c0/\/", salt, function(err, hash) {
47 |         // Store hash in your password DB.
48 |     });
49 | });
50 | ```
51 | 
52 | **To check a password:**
53 | ```javascript
54 | // Load hash from your password DB.
55 | bcrypt.compare("B4c0/\/", hash, function(err, res) {
56 |     // res === true
57 | });
58 | bcrypt.compare("not_bacon", hash, function(err, res) {
59 |     // res === false
60 | });
61 | // As of bcryptjs 2.4.0, compare returns a promise if callback is omitted:
62 | bcrypt.compare("B4c0/\/", hash).then((res) => {
63 |     // res === true
64 | });
65 | ```
66 | 
67 | **Auto-gen a salt and hash:**
68 | ```javascript
69 | bcrypt.hash('bacon', 8, function(err, hash) {
70 | });
71 | ```


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/cat.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: cat Linux Command
  3 | description: cat command is used to create, read & concatenate files in Linux/ Unix machines
  4 | created: 2019-08-21
  5 | updated: 2022-10-05
  6 | ---
  7 | 
  8 | `cat` command is used to create, read & concatenate files in Linux/ Unix machines. 
  9 | 
 10 | ## 1. Creating a file with content
 11 | Lets create a file with name `file1.txt` and put following three lines of content into it. 
 12 | 
 13 | First you need to run the following command to create a file
 14 | 
 15 | ```sh
 16 | cat >file1.txt
 17 | ```
 18 | When you press enter after the above command, it waits for the file content input. You can give multi line input and once you are done you need to press `CTRL + D` to save and exit. 
 19 | 
 20 | 
 21 | ## 2. Displaying file contents 
 22 | Following command shows the content of given file
 23 | ```sh
 24 | cat file1.txt
 25 | ```
 26 | ## 3. Display content from multiple files
 27 | Following command shows content from file1.txt followed by content from file2.txt
 28 | 
 29 | ```sh
 30 | cat file1.txt file2.txt
 31 | ```
 32 | 
 33 | ## 4. Copy the contents of one file to another file
 34 | Following command copies content from file1.txt to file2.txt
 35 | 
 36 | ```sh
 37 | cat file1.txt > file2.txt
 38 | ```
 39 | 
 40 | ## 5. Append the contents of one file to the end of another file
 41 | Following command appends content of file1.txt to the end of file2.txt
 42 | 
 43 | ```sh
 44 | cat file1.txt >> file2.txt
 45 | ```
 46 | 
 47 | ## 6. Display content in reverse order
 48 | Following command displays content of file1.txt in reverse order
 49 | 
 50 | ```sh
 51 | tac file1.txt
 52 | ```
 53 | 
 54 | ## 7. Open dashed files
 55 | Following command displays content of -dashfile
 56 | 
 57 | ```sh
 58 | cat -- "-dashfile"
 59 | ```
 60 | 
 61 | ## 8. If the file has a lot of content and can’t fit in the terminal
 62 | ```sh
 63 | cat "filename" | more
 64 | ```
 65 | 
 66 | ## 9. Merge the contents of multiple files
 67 | ```sh
 68 | cat "filename1" "filename2" "filename3" > "merged_filename"
 69 | ```
 70 | 
 71 | ## 10. Display Line Numbers before every line 
 72 | 
 73 | Following command prefixes line numbers before each line from content
 74 | 
 75 | ```sh
 76 | cat -n file1.txt
 77 | ```
 78 | Following is an example for that 
 79 | 
 80 | ```sh
 81 | $ cat -n file1.txt
 82 |      1	line-1
 83 |      2	line-2
 84 |      3	line-3
 85 |      4	line-4
 86 | ```
 87 | 
 88 | ## 11. Display content with More & Less Options
 89 | If a file having a large number of content that won’t fit in the output terminal and the screen scrolls up very fast, we can use parameters more and less with the cat command as shown below.
 90 | 
 91 | ```sh
 92 | cat song.txt | more
 93 | cat song.txt | less
 94 | ```
 95 | 
 96 | ## More Options
 97 | 
 98 | |Option| Description|
 99 | |---|---|
100 | |`-e`|Shows `$` at the end of the content|
101 | |`-t`|To see tabs in file, this shows tabs with `^I`|
102 | |`-s`|Removes repeated empty lines in content|
103 | |`-E`|Highlights the end of line|
104 | 


--------------------------------------------------------------------------------
/cd.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: cd Linux Command
 3 | description: cd command is used to change the current working directory
 4 | created: 2019-08-21
 5 | updated: 2023-10-12
 6 | ---
 7 | 
 8 | `cd` command is used to change the current working directory
 9 | 
10 | ## Changing to a directory with path 
11 | 
12 | ```sh
13 | cd /path/to/new/directory
14 | ```
15 | 
16 | ## change directory to the root directory
17 | 
18 | ```sh
19 |  cd /
20 |  ```
21 |  
22 | ## Change to current logged in user's home directory
23 | 
24 | ```sh
25 | cd ~
26 | ```
27 | ```sh
28 | cd
29 | ```
30 | 
31 | ## Change to a directory whih is an immediatsub directy to you rcurrent directory
32 | 
33 | For example lets take following is your directory structure
34 | 
35 | ```
36 | ├── images
37 | ├── movies
38 | │   ├── action
39 | │   └── comedy
40 | └── music
41 | ```
42 | and let's say you are in movies currently, so to go to action you can simply run the following command
43 | 
44 | ```sh
45 | cd action
46 | ```
47 | 
48 | ```
49 | ├── images
50 | ├── 'My movies'
51 | │   ├── action
52 | │   └── comedy
53 | └── music
54 | ```
55 | 
56 | ```sh
57 | cd My\ movies
58 | ```
59 | ## Going back to immediate parent directoty of current directoty 
60 | 
61 | ```sh
62 | cd ..
63 | ```
64 | ## change directory to the last working directory
65 | 
66 | ```sh
67 |  cd -
68 |  ```


--------------------------------------------------------------------------------
/challenges-code-preloads.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: OneCompiler challenges code preloads
 3 | description: OneCompiler challenges code preloads helps populating boilerplate code for the problems so that users don't have to start from scratch. 
 4 | created: 2022-09-18
 5 | updated: 2022-09-18
 6 | ---
 7 | 
 8 | OneCompiler challenges code preloads helps populating boilerplate code for the problems so that users don't have to start from scratch. Typically preloads populate code for reading inouts from console. 
 9 | 
10 | # How to add preloads? 
11 | While editing a problem under challenge, click on `Additional options:` in the section you see `code ids` textarea where you can keep comma seperated code ids to preload from different languages. 
12 | 
13 | # Common preloads
14 | Following are the common preloads for popular languages, these covers basic syntax for reading STDIN. 
15 | 
16 | ```
17 | 3ygcd9fxd, 3ygcdatnw, 3ygcdcmfr, 3ygcdense
18 | ```
19 | 


--------------------------------------------------------------------------------
/chmod.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: chmod Linux Command
 3 | description: chmod stands for "change mode". It is used to change the permissions to files/ directories
 4 | created: 2019-08-24
 5 | updated: 2023-10-12
 6 | ---
 7 | 
 8 | chmod stands for "change mode". It is used to change the permissions to files/ directories
 9 | 
10 | # Syntax
11 | ```sh
12 | chmod [options] <permissions> <file_name> 
13 | ```
14 | # Options
15 | 
16 | |Option|Description|
17 | |---|---|
18 | |-R|change permissions for files and directories recursively|
19 | |-v|Verbose(this display all the files that the command is processing)|
20 | |-c|Change (this will display only the files it is changing the permission for)|
21 | |-f|silent mode (this will supress errors)|
22 | |-h|this change the permission of the symbolic link instead of the main file|
23 | 
24 | ### Example 
25 | ```sh
26 | chmod 777 foo.txt
27 | ```
28 | 
29 | # Permissions 
30 | Following are the four possible digits and their respective permissions
31 | 
32 | |Digit| Permission|
33 | |---|---|
34 | |4|read|
35 | |2|write|
36 | |1|execute|
37 | |0|no permission|
38 | 
39 | Users can also sumup these digits and can use like following 
40 | 
41 | |Derived Digits| Permission|
42 | |---|---|
43 | |7| 4+2+1 = read + write + execute|
44 | |6| 4+2 = read + write|
45 | |5| 4+1 = read + execute|
46 | |3| 2+1 = write + execute|
47 | 
48 | # Permissions for user, group, others
49 | Owner of the file can set different permissions for user, group & others 
50 | 
51 | ### Example
52 | ```sh
53 | chmod u=rwx,g=rx,o=r foo.sh # this is same as chmod 754 foo.sh
54 | ```
55 | 
56 | ```
57 | u = user
58 | g = group
59 | o = others
60 | 
61 | r = read
62 | w = write
63 | x = execute
64 | ```
65 | 


--------------------------------------------------------------------------------
/cksum.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: cksum Linux Command
 3 | description: cksum Linux command is used to generate checksum value for a file or stream of data. cksum reads files given in its arguments and calculates checksum, if no arguments provided then it reads the standard input.
 4 | created: 2019-08-25
 5 | updated: 2019-08-25
 6 | ---
 7 | 
 8 | `cksum` Linux command is used to generate checksum value for a file or stream of data. cksum reads files given in its arguments and calculates checksum, if no arguments provided then it reads the standard input.
 9 | 
10 | # Syntax 
11 | 
12 | ```sh
13 | cksum [OPTION]... [FILE]...
14 | ```
15 | 
16 | ### Example
17 | 
18 | ```sh
19 | $ cksum readme.txt 
20 | 2116921653 13 readme.txt
21 | ```
22 | 
23 | ```
24 | 2116921653 13 readme.txt
25 | |          |  |__ file name 
26 | |          |
27 | |          |_____ file size in bytes
28 | |
29 | |________________ Checksum value
30 | 
31 | ```


--------------------------------------------------------------------------------
/cmp.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: cmp Linux Command
 3 | description: cmp Linux command is used to compare 2 files byte by byte. It reports the byte, line number where the first difference is found. If no difference, no output will return. The optional SKIP1 and SKIP2 specify the number of bytes to skip at the beginning of each file (zero if nothing specified).
 4 | created: 2019-08-26
 5 | updated: 2019-08-26
 6 | ---
 7 | 
 8 | `cmp` Linux command is used to compare 2 files byte by byte. It reports the byte, line number where the first difference is found.
 9 | If no difference, no output will return. The optional SKIP1 and SKIP2 specify the number of bytes to skip at the beginning of each file (zero if nothing specified).
10 | 
11 | # Syntax 
12 | 
13 | ```sh
14 | cmp [OPTION]... FILE1 [FILE2 [SKIP1 [SKIP2]]]
15 | ```
16 | 
17 | # Basic Command syntax
18 | ```sh
19 | cmp [OPTION]... FILE1 FILE2
20 | ```
21 | 
22 | ### Example
23 | 
24 | ```sh
25 | $ cmp file1.txt file2.txt
26 | file1.txt file2.txt differ: char 2, line 1
27 | ```
28 | 


--------------------------------------------------------------------------------
/comm.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: comm Linux Command
 3 | description: comm Linux Command compare two sorted files line by line and write to output, It requires two sorted files which it compares line by line.
 4 | created: 2019-08-26
 5 | updated: 2019-08-26
 6 | ---
 7 | 
 8 | `comm` Linux Command compare two sorted files line by line and write to output, It requires two sorted files which it compares line by line.
 9 | 
10 | # Syntax 
11 | 
12 | ```sh
13 | comm [OPTION]... FILE1 FILE2
14 | ```
15 | 
16 | # Options
17 | 
18 | |Option|Description|
19 | |---|---|
20 | |-1|suppress printing of the first column (lines unique to the first file)|
21 | |-2|suppress printing of the second column (lines unique to the second file)|
22 | |-3|suppress printing of the third column (lines common to both the files)|
23 | |–-check-order|check's the input is correctly sorted, even if all the input lines are pairable|
24 | |–-nocheck-order|do not check that the input is correctly sorted|
25 | |–-output-delimiter=STR|separate columns with string STR|
26 | 
27 | 
28 | ### Example
29 | 
30 | ```sh
31 | $cat >file1.txt
32 | one
33 | two
34 | three
35 | 
36 | $cat >file2.txt
37 | one
38 | three
39 | four
40 | 
41 | $comm file1.txt file2.txt
42 | 		one
43 | 	three
44 | 	four
45 | two
46 | three
47 | ```
48 | 


--------------------------------------------------------------------------------
/commonlisp.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Common Lisp 
  3 | description: Common Lisp cheatsheet gives you a quick reference to code syntax with examples makes it handy while coding.
  4 | created: 2020-07-05
  5 | updated: 2020-07-05
  6 | ---
  7 | 
  8 | ## Sample program
  9 | 
 10 | ```lisp
 11 | (setq name (read))
 12 | (princ "Hello ")
 13 | (write name)
 14 | ```
 15 | * **read** : used to read the data from console
 16 | * **setq** : used to create and assign values to the variables
 17 | * **princ** : used to print the output to the console
 18 | * **write** : used to write output to the console
 19 | * **`;`** : Indicates a comment line.
 20 | 
 21 | ## Variables
 22 | 
 23 | Multiple ways to declare variables
 24 | ### Example
 25 | 
 26 | ```lisp
 27 | (defvar x 10)
 28 | (write x)
 29 | ```
 30 | * `let` and `prog`are used to declare local variables.
 31 | 
 32 | ```lisp
 33 | (let ((var1  value1) (var2  value2).. (varn  valuen))<expressions>)
 34 | ```
 35 | * `setq` is used to declare both global and local variables.
 36 | 
 37 | ```lisp
 38 | (setq a 10)
 39 | ```
 40 | ## Macros
 41 | ```lisp
 42 | (defmacro macroName (parameter-list))
 43 | "Optional string for documentation"
 44 | ;body
 45 | ```
 46 | ## Constants
 47 | ```lisp
 48 | (defconstant constName value)
 49 | ```
 50 | ### Example
 51 | ```lisp
 52 | (defconstant PI 3.141592)
 53 | ```
 54 | ## Operators
 55 | 
 56 | | Operator type | Description|
 57 | |----|-----|
 58 | | Arithmetic Operator|+ , - , * , / , rem, mod,incf,decf|
 59 | | Relational Operator| < , > , <= , >=, /= , ==, max, min|
 60 | | Logical Operator| and, or, not|
 61 | | Bitwise Operator | logand, logior, lognor, logxor, logeqv|
 62 | 
 63 | ## Conditional statements
 64 | 
 65 | ### 1. If
 66 | ```lisp
 67 | (if [test] [then do this] [else do this])
 68 | ```
 69 | 
 70 | ### 2. When
 71 | ```lisp
 72 | (when ([conditional-expr])
 73 |     ([do this])
 74 |     ([do this])
 75 |     ([do this, which returns value]))
 76 | ```
 77 | ### 3. Case
 78 | 
 79 | ```lisp
 80 | (cond   (condition1    action1)
 81 |         (condition2    action2)
 82 |         ...
 83 |         (conditionn   actionn))
 84 | ```
 85 | 
 86 | ## Loops
 87 | 
 88 | ### 1. Loop
 89 | 
 90 | ```lisp
 91 | (loop (s-expressions))
 92 | ```
 93 | 
 94 | ### 2. For
 95 | 
 96 | ```lisp
 97 | (loop for loop-variable in <a list>
 98 |    do (action)
 99 | )
100 | ```
101 | ### 3. Do
102 | 
103 | ```lisp
104 | (do ((var1    val1   updated-val1)
105 |       (var2   val2   updated-val2)
106 |       (var3   val3   updated-val3)
107 |    ...)
108 |    (test return-value)
109 |    (s-expressions)
110 | )
111 | ```
112 | 
113 | ### 4. Dotimes
114 | 
115 | ```lisp
116 | (dotimes (n val)
117 |   statements
118 | ```
119 | ## Arrays
120 | 
121 | ```lisp
122 | (setf arrayName (make-array '(length)))
123 | ```
124 | ## Lists
125 | 
126 | ```lisp
127 | (list 1 2 3 4 5)
128 | (list 'a 'b 'c 'd 'e)
129 | ```
130 | |List methods| Usage|Description|
131 | |----|----|----|
132 | | cons | (cons 'a '(b c)) --> (A B C) |  used to put together list items|
133 | |append| (append '(a b) '(c d)) --> (A B C D) | Used to append lists|
134 | |reverse| (reverse '(a b c)) --> (C B A) | used to reverse the list items|
135 | |sort |(sort '(0 5 1 3 2) #'>) --> (5 3 2 1 0)| used to sort the list items|
136 | |substitute | (substitute 'y 'x '(x 1 x 2)) --> (Y 1 Y 2) | used to substitute the list items with the given value|
137 | |length|(length '(1 2 3 4 5)) --> 5 used to find the length of a list||
138 | |count |(count '1 '(1 2 1 2 1)) --> 3| to count the occurence of a list item|
139 | |remove| (remove 'item list) | removes the given item from list|
140 | 
141 | ## Hash Table
142 | 
143 | ```lisp
144 | make-hash-table &key :test :size :rehash-size :rehash-threshold
145 | ```
146 | 
147 | ## Structures
148 | 
149 | ```lisp
150 | (defstruct structureName 
151 |     ; structureElements
152 | )
153 | ```
154 | 


--------------------------------------------------------------------------------
/cp.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: cp Linux Command
 3 | description: cp stands for copy. This command is used to copy files or directories. cp command require at least two filenames in its arguments.
 4 | created: 2019-08-26
 5 | updated: 2019-08-26
 6 | ---
 7 | 
 8 | `cp` stands for copy. This command is used to copy files or directories. cp command require at least two filenames in its arguments.
 9 | 
10 | # Syntax 
11 | 
12 | ```sh
13 | cp [OPTION] SourcePath DestinationPath
14 | ```
15 | 
16 | # Options
17 | 
18 | |Option|Description|
19 | |---|---|
20 | |-a|archive files|
21 | |-f|force copy by removing/overriding the destination file (if already present)|
22 | |-i|interactive mode override (asks before overwrite)|
23 | |-l|linkes the files instead copy|
24 | |-L|follows symbolic links|
25 | |-n|no file overwrite, if destination file already exists|
26 | |-R|recursive copy (this includes hidden files)|
27 | |-u|update mode i.e copy only when source is newer than dest|
28 | |-v|verbose mode i.e prints more information|
29 | 
30 | ### Example
31 | 
32 | ```sh
33 | $ cp file1.txt file2.txt
34 | $ ls
35 | file1.txt	file2.txt
36 | ```
37 | 


--------------------------------------------------------------------------------
/cron.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: cron
 3 | description: Cron is a time-based job scheduler, Used to automate tasks need to be executed repeatedly at particular intervals.
 4 | created: 2019-08-20
 5 | updated: 2019-08-20
 6 | ---
 7 | 
 8 | Cron is a time-based job scheduler, Used to automate tasks need to be executed repeatedly at particular intervals.
 9 | 
10 | 
11 | ## Cron format
12 | ```sh
13 | * * * * *
14 | | | | | |
15 | | | | | Day of week
16 | | | | Month
17 | | | Day of month
18 | | Hour
19 | Minute
20 | ```
21 | 
22 | |Field|Range|Special characters
23 | |------|-----|-----|
24 | |Minute|0 - 59|, - * /|
25 | |Hour|0 - 23|, - * /|
26 | |Day of Month|1 - 31|, - * ? / L W|
27 | |Month|1 - 12|, - * /|
28 | |Day Of Week|0 - 6|, - * ? / L #|
29 | 
30 | ## Special characters 
31 | 
32 | |Special Character|Description|
33 | |------|-----|
34 | |Asterik(*)| Matches all values in the field or any possible value.|
35 | |Hyphen(-)|Used to define a range.Ex: 1-5 in 5th field(Day Of Week) Every Weekday i.e., Monday to Friday|
36 | |Slash (/)|1st field(Minute) /15 meaning every fifteen minute or increment of range.|
37 | |Comma (,)| Used to separate items.Ex: 2,6,8 in 2nd fields(Hour) executes at 2am,6am and 8am|
38 | |L|It is allowed only for Day of Month or Day Of Week field, 2L in Day of week indicates Last tuesday of every month|
39 | |Hash (#)|It is allowed only for Day Of Week field, which must be followed within range of 1 to 5. For example, 4#1 means "The first Thursday" of given month.|
40 | |Question mark (?)|Can be instead of '*' and allowed for Day of Month and Day Of Week. Usage is restricted to either Day of Month or Day Of Week in a cron expression.|
41 | 
42 | 
43 | ## Cron Expression Examples
44 | 
45 | |Cron Expression|Description|
46 | |------|-----|
47 | |* * * * *|Executes a cron job for every minute|
48 | |*/5 * * * *|Executes a cron job for every 5 minutes|
49 | |0/5 2,5 * * *|Executes a cron job for every 5 minutes starting at 2am and ending at 2:55am and for every 5 minutes starting at 5am and ending at 5:55am every day|
50 | |0 12 * * *|Executes a cron job at 12pm every day|
51 | |0 12 * * ?|Executes a cron job at 12pm every day|
52 | |* 2 * * *|Executes a cron job for every minute starting at 2am and ending at 2:59am every day|
53 | |15 2 * * ?|Executes a cron job at 2:15am every day|
54 | |15 2 * * 1L|Executes a cron job at 2:15am on the last monday of every month|
55 | |15 0 * * 4#2|Executes a cron job at 00:15am on the second thursday of every month|
56 | 
57 | 
58 | ## Basic crontab commands
59 | 
60 | Edit crontab file
61 | ```sh
62 | crontab -e
63 | ```
64 | View crontab file
65 | ```sh
66 | crontab -l
67 | ```
68 | Remove crontab file
69 | ```sh
70 | crontab -r
71 | ```


--------------------------------------------------------------------------------
/crontab.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: crontab Linux Command
 3 | description: crontab Linux command is used to run specified tasks at regular interval of time.
 4 | created: 2019-09-10
 5 | updated: 2019-09-10
 6 | ---
 7 | 
 8 | crontab Linux command is used to run specified tasks at regular interval of time.
 9 | 
10 | # Syntax 
11 | 
12 | ```sh
13 | [cron_expression] [command]
14 | ```
15 | ```
16 | cron_expression -> [Minute] [hour] [Day_of_the_Month] [Month_of_the_Year] [Day_of_the_Week] 
17 | ```
18 | 
19 | # Commands
20 | 
21 | 
22 | ```sh
23 | crontab -l   # Lists the crontab entries for the current user
24 | ```
25 | 
26 | ```sh
27 | crontab -u <username> -l # lists crontab entries for given user
28 | ```
29 | 
30 | ```sh
31 | crontab -e # Opens crontab file for current user, where user can add more entries
32 | ```
33 | 
34 | ```sh
35 | crontab -u <username> -e # opens crontab file of specified user
36 | ```
37 | 
38 | 
39 | # Examples
40 | 
41 | ```sh
42 | * * * * * ./batch_script.sh
43 | | | | | | |_ script/ command to run at regular interval of time
44 | | | | | |___ day of week (0 - 7) 0,7 are for sunday
45 | | | | |_____ month of year (1 - 12)
46 | | | |_______ day of month (1- 31)
47 | | |_________ hour (0 - 23)
48 | |___________ minute (0 - 59)
49 | ```
50 | 
51 | |Expression | Description|
52 | |---|---|
53 | | */5 * * * * |Every 5 Minutes|
54 | | */30 * * * * |Every 30 Minutes|
55 | | * */1 * * * |Every 1 Hour|
56 | | * */3 * * * |Every 3 Hours|
57 | | 0 0 * * * |Everyday at 00:00|
58 | | 0 1 * * * | Everyday at 1AM|
59 | | 0 0 * * SUN | Every Sunday|
60 | | 0 0 * * 0 | Every Sunday|
61 | | 0 0 1 * * | Every Month 1st day 00:00|
62 | | 0 0 1 1 * | Every year 1st month 1st day 00:00|


--------------------------------------------------------------------------------
/curl.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: cURL Command
 3 | description: cURL is a cross platform command line tool which helps to make requests to server. Mainly used for making http calls but it can also do FILE, FTP, IMAP, LDAP, POP3, SCP, SFTP, SMTP, TELNET, TFTP and many more
 4 | created: 2019-06-17
 5 | updated: 2019-06-17
 6 | ---
 7 | 
 8 | ## Fetch content from a URL
 9 | ```sh
10 | curl <url>
11 | ```
12 | Example
13 | ```sh
14 | curl https://onecompiler.com/
15 | ```
16 | 
17 | ## More Options
18 | 
19 | |Option|Description|Example|
20 | |---|---|---|
21 | |`-O`|To download a file|`curl -O https://static.onecompiler.com/images/logo/logo_transparent.png`|
22 | |`-OC`|To download a file with resume capability|`curl -OC https://static.onecompiler.com/images/logo/logo_transparent.png`|
23 | |`-L`|Follow url redirects|`curl -L https://onecompiler.com/`|
24 | |`--max-redirs`|Maximum redirects|`curl -L --max-redirs 5 https://onecompiler.com/`|
25 | |`-v`|Verbose mode to see request, response headers & Connection information|`curl -v https://onecompiler.com/`|
26 | |`-H`|To ser request headers|`curl -H 'User-Agent: Robot' https://onecompiler.com/`|
27 | |`-X`|To specify request method|`curl -X POST https://httpbin.org/post`|
28 | 
29 | 
30 | ## Frequently used Headers
31 | Following are some of the commonly used headers with examples
32 | 
33 | 1. User-Agent
34 | example: 
35 | ```sh
36 | curl -H 'User-Agent: Robot' https://onecompiler.com/
37 | ```
38 | 
39 | 2. Host
40 | example:
41 | ```sh
42 | curl -H 'Host: onecompiler.com' https://onecompiler.com/
43 | ```
44 | 
45 | 


--------------------------------------------------------------------------------
/cut.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: cut Linux Command
 3 | description: cut Linux Command is used to extract sections from each line of input or from a file. Extraction of line segments can be done by bytes (-b),  characters (-c), fields (-f) or by delimiter (-d)  tab character is the default delimiter.
 4 | created: 2019-09-11
 5 | updated: 2019-09-11
 6 | ---
 7 | 
 8 | cut Linux Command is used to extract sections from each line of input or from a file. Extraction of line segments can be done by bytes (-b),  characters (-c), fields (-f) or by delimiter (-d)  tab character is the default delimiter.
 9 | 
10 | ## Segment types
11 | 
12 | |segment|description|
13 | |---|---|
14 | |-b| bytes|
15 | |-c| characters |
16 | |-f| fields|
17 | |-d|delimiter. Note: tab is the default delimiter|
18 | 
19 | 
20 | ## Range specification
21 | |Range|description|
22 | |---|---|
23 | |N| Nth|
24 | |N-M| N to M|
25 | |N-|N to end of line|
26 | |-M|beginning to M|
27 | 
28 | Note: N, M counted from 1, not 0.
29 | 
30 | ## Examples 
31 | 
32 | Lets say we have a file `foo.txt` with following content
33 | 
34 | ```
35 | abc-def-ghi-jkl
36 | mno-pqr-stu-vwx
37 | 123-456-7890
38 | ```
39 | 
40 | ```sh
41 | $ cut -c 5-7 foo.txt 
42 | def
43 | pqr
44 | 456
45 | ```
46 | 
47 | ```sh
48 | $ cut -d "-" -f 1-2 foo.txt 
49 | abc-def
50 | mno-pqr
51 | 123-456
52 | ```
53 | 
54 | ```sh
55 | $ cut -c 5- foo.txt
56 | def-ghi-jkl
57 | pqr-stu-vwx
58 | 456-7890
59 | 
60 | ```


--------------------------------------------------------------------------------
/dns.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: DNS Records
 3 | description: DNS (Domain Name System) takes a human friendly domain names as input and translate that to an IP Address. There are various record types like A record, CNAME, MX, TXT, SRV, AAAA etc.,
 4 | created: 2019-06-25
 5 | updated: 2022-10-01
 6 | color: #60a3bc
 7 | ---
 8 | 
 9 | DNS (Domain Name System) takes a human friendly domain names as input and translate that to an IP Address. There are various record types like A record, CNAME, MX, TXT, SRV, AAAA etc.,
10 | 
11 | ## Major DNS record types
12 | |Record Type|Description|
13 | |---|---|
14 | |A Record|Points to an IPv4 address|
15 | |AAAA|Similar to `A` but this allows to point to an `IPv6 address`|
16 | |CNAME (Canonical Name)| Points to another domain name|
17 | |MX (Mail Exchanger)| Directs email to a mail server|
18 | |TXT| Map domain to text, mostly for information. Often used for verification purpose|
19 | |SRV|Points to a domain name using a specific destination port|
20 | 
21 | ## Other DNS record types
22 | |Record Type|Description|
23 | |---|---|
24 | |CAA|Provide additional confirmation for the Certification Authority when validating an SSL certificate|
25 | |CERT|Provides a space in the DNS for certificates and related certificate revocation lists|
26 | |DNSKEY|Contains a public signing key (usually for DNSSEC)|
27 | |DS|Refers to a DNSKEY resource record by including a digest of that DNSKEY resource record|
28 | |LOC|Expressing geographic location information for a domain name|
29 | |NS|Contains the name of the authoritative name server within a domain or DNS zone|
30 | |PTR|Verify that the sender matches the IP address it claims to be using|
31 | |SPF|Lists all the servers authorized to send emails from a particular domain|
32 | |SSHFP|Identifies SSH keys that are associated with a host name.|
33 | |TLSA|Associate a TLS server certificate or public key with the domain name where the record is found|
34 | |URI|Means for publishing mappings from hostnames to URIs|
35 | 


--------------------------------------------------------------------------------
/docker.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Docker
 3 | description: Docker Build, Ship and Run commands
 4 | created: 2018-10-22
 5 | updated: 2022-10-01
 6 | ---
 7 | 
 8 | ## Build
 9 | Building an image from Dockerfile 
10 | ```sh
11 | docker build -t app_name:1.0 .
12 | ```
13 | List all images
14 | ```sh
15 | docker images
16 | ```
17 | 
18 | ## Ship
19 | Push docker image
20 | ```sh
21 | docker push user_id/my_image
22 | ```
23 | ## Run
24 | Run docker image
25 | ```sh
26 | docker run -p 8001:8001 -it  app_name:1.0
27 | ```
28 | 
29 | List all running containers
30 | ```sh
31 | docker ps
32 | ```
33 | 
34 | Kill a running container
35 | 
36 | ```sh
37 | docker kill container_name/ container_id 
38 | ```
39 | 
40 | ## Container
41 | 
42 | List running containers
43 | 
44 | ```
45 | docker container ls
46 | ```
47 | 
48 | List all containers even stopped once
49 | 
50 | ```
51 | docker container ls -a
52 | ```
53 | 
54 | Start and stop a container
55 | 
56 | ```
57 | docker start container_name 
58 | docker stop container_name
59 | ```
60 | 
61 | Create a image from a running container
62 | 
63 | ```
64 | docker container commit container_id image_name
65 | ```
66 | 
67 | Delete all stopped containers
68 | 
69 | ```
70 | docker container prune
71 | ```
72 | 
73 | Get all details related to the container
74 | 
75 | ```
76 | docker inspect container_id
77 | ```
78 | 
79 | 
80 | 
81 | ## Prune
82 | 
83 | ```sh
84 | docker system prune     # prune all docker resources
85 | docker system prune -f  # prune all resources with force (without prompt)
86 | ```
87 | 
88 | ## Dockerfile syntax
89 | 
90 | ```sh
91 | FROM ubuntu:16.04 # from base image
92 | RUN apt-get update # execute commands
93 | ADD local_directory /
94 | EXPOSE 8080
95 | 
96 | ```
97 | 


--------------------------------------------------------------------------------
/dockerfile.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Dockerfile Syntax
  3 | description: Dockerfile Syntax
  4 | created: 2019-09-15
  5 | updated: 2019-09-15
  6 | ---
  7 | 
  8 | ## FROM
  9 | 
 10 | Syntax
 11 | ```sh
 12 | FROM <image>:<tag>
 13 | ```
 14 | Example
 15 | ```sh
 16 | FROM ubuntu:16.04
 17 | ```
 18 | 
 19 | ## ENV
 20 | 
 21 | Syntax
 22 | ```sh
 23 | ENV <key> <value>
 24 | ```
 25 | 
 26 | Example
 27 | ```sh
 28 | ENV JAVA_HOME       /usr/lib/jvm/java-8-oracle
 29 | ```
 30 | 
 31 | ## RUN
 32 | 
 33 | Syntax
 34 | ```sh
 35 | RUN <command>
 36 | ```
 37 | 
 38 | Example
 39 | ```sh
 40 | RUN apt-get update
 41 | ```
 42 | 
 43 | ## EXPOSE
 44 | 
 45 | Syntax
 46 | ```sh
 47 | EXPOSE <port> [<port> ...]
 48 | ```
 49 | 
 50 | Example
 51 | ```sh
 52 | EXPOSE 8080 9200
 53 | ```
 54 | ## COPY
 55 | 
 56 | Syntax
 57 | ```sh
 58 | COPY <src> [<src> ...] <dest>
 59 | ```
 60 | 
 61 | Example
 62 | ```sh
 63 | COPY file1.txt /opt/app/file1.txt
 64 | ```
 65 | 
 66 | ## ADD
 67 | 
 68 | Syntax
 69 | ```sh
 70 | ADD <src> [<src> ...] <dest>
 71 | ```
 72 | 
 73 | Example
 74 | ```sh
 75 | ADD file1.txt /opt/app/file1.txt
 76 | ADD jdk-8u120-linux-x64.tar.gz /usr/local/  # ADD unzips for you
 77 | ADD http://example.com/app.tar.xz /opt/app/ # ADD also support urls
 78 | ```
 79 | 
 80 | ## VOLUME
 81 | Syntax
 82 | ```sh
 83 | VOLUME </path/from/host> </path/from/docker-container>
 84 | ```
 85 | 
 86 | Example
 87 | ```sh
 88 | VOLUME /data /mongodb/db/data
 89 | ```
 90 | 
 91 | ## WORKDIR
 92 | Sets working directory where other commands run
 93 | Syntax 
 94 | ```sh
 95 | WORKDIR <path>
 96 | ```
 97 | 
 98 | Example
 99 | ```sh
100 | WORKDIR /opt/app
101 | ```
102 | 
103 | ## CMD
104 | Syntax 
105 | ```sh
106 | CMD <command> [<command> ...]
107 | ```
108 | 
109 | Example
110 | ```sh
111 | CMD ['node' 'index.js']
112 | ```
113 | 


--------------------------------------------------------------------------------
/dotenv.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: dotenv (Nodejs Library)
 3 | description: dotenv loads the environment variables from .env file to process.env
 4 | created: 2019-06-21
 5 | updated: 2019-06-21
 6 | ---
 7 | 
 8 | dotenv loads environment variables from .env file to process.env
 9 | 
10 | ## Installation
11 | 
12 | ```sh
13 | npm install dotenv
14 | ```
15 | 
16 | ## Usage
17 | Add the folllowing line in the beginning of your Node application. This loads the environemnt variables from `.env` file to process.env
18 | 
19 | ```javascript
20 | require('dotenv').config()
21 | ```
22 | 
23 | ## `.env` file syntax
24 | 
25 | ```sh
26 | APPLICATION_PORT=8080
27 | ```
28 | 
29 | once this is defined you can access using `process.env.APPLICATION_PORT`
30 | 


--------------------------------------------------------------------------------
/echo.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: echo Linux Command
 3 | description: echo Linux Command used to output text to screen. This is available in most of the operating systems along with Linux systems.
 4 | created: 2019-09-12
 5 | updated: 2019-09-12
 6 | ---
 7 | 
 8 | echo Linux Command used to output text to screen. This is available in most of the operating systems along with Linux systems.
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | echo [option(s)] [string(s)]
15 | ```
16 | 
17 | ## Examples
18 | 
19 | ```sh
20 | echo Hello World! #=> Hello World!
21 | ```
22 | 
23 | ```sh
24 | x=5
25 | echo $x #=> 5
26 | ```
27 | 
28 | ```sh
29 | x=8
30 | echo x value is $x #=> x value is 8
31 | ```
32 | 
33 | ```sh
34 | echo Hello \nWorld! #=> Hello
35 |                     #   World!
36 | ```
37 | `Note: \n is for new line`
38 | 
39 | ```sh
40 | echo Hello \tWorld! #=> Hello   World!
41 | ```
42 | `Note: \t is for tab
43 | 
44 | ```sh
45 | echo * #=> Prints files and folders of current directory
46 | ```
47 | 
48 | ```sh
49 | echo *.txt #=> Prints all .txt files from current directory
50 | ```
51 | 
52 | - Using option new Line ‘\n‘ and horizontal tab ‘\t‘ simultaneously.
53 | ```sh
54 | $ echo -e "\n\Onecompiler \n\tis \n\ta \n\tcommunity \n\tof \n\tNerds" 
55 | 
56 | 	Onecompiler
57 | 	is 
58 | 	a 
59 | 	community 
60 | 	of
61 | 	Nerds 
62 | ```
63 | 


--------------------------------------------------------------------------------
/ejs-embedded-javascript-templates.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: EJS ( Embedded JavaScript templates )
 3 | description: EJS ( Embedded JavaScript templates ) is a simple templating language to generate HTML. Your code is plain Javascript in EJS, EJS itself does not introduce any new syntax. You can use EJS at client side or server side. 
 4 | created: 2018-10-24
 5 | updated: 2018-10-24
 6 | ---
 7 | 
 8 | EJS - EJS ( Embedded JavaScript templates ) is a simple templating language to generate HTML. Your code is plain Javascript in EJS, EJS itself does not introduce any new syntax. You can use EJS at client side or server side.
 9 | 
10 | 
11 | #### Sample Syntax
12 | 
13 | ```javascript
14 | <% if (user.email) { %>
15 |   <h1><%= user.email %></h1>
16 | <% } %>
17 | ```
18 | 
19 | ##### Usage - 1
20 | 
21 | ```javascript
22 | var templateString = '<h1> Hello, <%= userName %> </h1>';
23 | var options = {};
24 | 
25 | var template = ejs.compile(templateString, options);
26 | 
27 | var data = {
28 |     userName : 'Foo Bar'
29 | }
30 | 
31 | var outputString = template(data); // outputString -> <h1> Hello, Foo Bar </h1>
32 | ```
33 | 
34 | ##### Usage - 2
35 | 
36 | ```javascript
37 | var outputString = ejs.render(templateString, data, options);
38 | ```
39 | 
40 | ##### Usage - 3 (Template as a separate file)
41 | 
42 | ```javascript
43 | ejs.renderFile(templateFilePath, data, options, function(err, outputString){
44 |     console.log(outputString);
45 | });
46 | ```
47 | 
48 | ##### Options
49 | | Option | Description |
50 | |--------|--------|
51 | |cache|To cache the compiled functions|
52 | |filename|used by `cache` and `includes`|
53 | |context|Function execution context|
54 | |compileDebug|enable/ disable debug|
55 | |rmWhitespace|removes leading and trailing whitespaces|
56 | 
57 | 
58 | ### Tags
59 | 
60 | | Tag | Desctiption |
61 | |--------|--------|
62 | |`<% `|This is a Scriptlet tag, used for control flows. This does not output anything|
63 | |`<%_ _%>`|'Whitespace Slurping' tag, this removes all whitespaces before it.|
64 | |`<%= %>`|Produces HTML escaped value|
65 | |`<%- %>`|HTML unescaped value (useful if you have generated html in database )|
66 | |`<%# %>`|Comment tag|
67 | |`<%%`| to output literal `<%`|
68 | |`%>`|Ending tag|
69 | |`-%>`|Trims following new line|
70 | |`_%>`|Remove white spaces after it|
71 | 
72 | 
73 | ### Includes
74 | 
75 | ##### include
76 | To include a tempate, needs a file name option, paths are relative
77 | 
78 | ```javascript
79 | <%- include('partials/navbar.ejs', data) %>
80 |   <h1> Title <h1>
81 |   <p> content </p>
82 | <%- include('partials/footer.ejs', data) %>
83 | ```
84 | 
85 | ### References
86 | Official Website: https://ejs.co/
87 | 
88 | GitHub Repository: https://github.com/mde/ejs
89 | 
90 | NPM Pacjage: https://www.npmjs.com/package/ejs
91 | 
92 | 


--------------------------------------------------------------------------------
/elixir.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Elixir
  3 | description: Elixir programming language cheatsheet contains useful code syntax which is handy while coding.
  4 | created: 2020-06-28
  5 | updated: 2020-06-28
  6 | ---
  7 | ## Sample program
  8 | 
  9 | ```elixir
 10 | IO.puts "Hello, World!"
 11 | ```
 12 | * **IO.puts** : To print output data to the console
 13 | * **#** : comment
 14 | 
 15 | ## Variables
 16 | Variables must be declared and assigned a value.
 17 | 
 18 | ```elixir
 19 | variable-name = value
 20 | ```
 21 | ## Data types
 22 | 
 23 | | Data type| Usage| Description|
 24 | |----|----|----|
 25 | | Numeric| x = 21 | Elixir supports not only integer and float values but also a number can be defined in octal, hexadecimal and binary bases.|
 26 | | Atom| :true | Atoms are constant values whose name is same as their value|
 27 | | Boolean | : false, :true| Either true or false, usually declared as atoms|
 28 | | Strings| "Hello"| Strings are enclosed in double quotes(" ") and multi line strings are enclosed in triple double quotes(""" """)|
 29 | | Lists| \['a', 10, :true\]| Lists are used to store different types of values and are represented in square brackets []|
 30 | | Tuples| {'apple', 100, :false} | Similar to Lists and are represented in curly brackets {}. Tuples are good for accessing the values and lists are good for insertion and deletion of values|
 31 | 
 32 | ## Reserved Keywords
 33 | 
 34 | |||||||
 35 | |----|----|----|----|----|----|
 36 | | after | and | catch | do | inbits | true|
 37 | | inlist | nil | else | end | not |  when|
 38 | | or| false | fn | in | rescue |   xor |
 39 | 
 40 | 
 41 | ## Operators
 42 | | Operator type | Description|
 43 | |----|-----|
 44 | | Arithmetic Operator|+ , - , * , / , div, rem|
 45 | | comparision Operator| < , > , <= , >=, !=, !==, === , ==|
 46 | | Bitwise Operator| &&& , ^^^ , \|\|\|, ~~~, <<<, >>>|
 47 | | Boolean Operator| and , or, not, &&, \|\|, ! |
 48 | 
 49 | ## Conditional Statements
 50 | 
 51 | ### 1. If
 52 | 
 53 | ```elixir
 54 | if condition do
 55 |   #Code 
 56 | end
 57 | ```
 58 | ### 2. If-Else
 59 | 
 60 | ```elixir
 61 | if condition do
 62 |   #Code 
 63 | else
 64 |   #code
 65 | end
 66 | ```
 67 | ### 3. Case
 68 | 
 69 | ```elixir
 70 | case value do
 71 |   value-1 -> #code if value matches value-1
 72 |   value-2 -> #code if value matches value-2
 73 |   value-3 -> #code if value matches value-3
 74 |   ...
 75 |   _ -> #code if value does not match any of the above and is similar to default in switch
 76 | end
 77 | ```
 78 | 
 79 | ## Loops
 80 | ### 1. Unless
 81 | 
 82 | ```elixir
 83 | unless condition do
 84 |   #Code 
 85 | end
 86 | ```
 87 | 
 88 | ### 2. Unless-Else
 89 | 
 90 | ```elixir
 91 | unless condition do
 92 |   #Code if condition fails
 93 | else
 94 |   #Code if condition satisfies
 95 | end
 96 | ```
 97 | ### 3. Cond
 98 | 
 99 | ```elixir
100 | cond do
101 |   condition-1 -> #code if condition is true
102 |   condition-2 -> #code if condition is true
103 |   ...
104 |   true -> #code if none of the above are true
105 | end
106 | ```
107 | 
108 | ## List
109 | 
110 | List is a collection of data of the same or different types and are stored in memory as linked lists.
111 | 
112 | ```elixir
113 | ["foo", 123, true]
114 | ```
115 | 
116 | |List Functions| Description|
117 | |----|----|
118 | | length()| returns the length of a list|
119 | | ++ | used to concatenate two lists by adding list items|
120 | | -- | used to concatenate two lists by substracting list items|
121 | | hd(list)| to get the first element of the list|
122 | | tl(list)| to get last element of the list|
123 | |  delete(list, item) | to delete an item from the list|
124 | | delete_at(list, index) | to delete an item at given index from the list|
125 | |insert_at(list, index, value)| to insert given item at specific index of a list|
126 | 
127 | ## Tuples
128 | 
129 | Tuples are collection of data of the same or different types and are stored contiguously in memory.
130 | 
131 | ```elixir
132 | tuple = {:foo, :bar}
133 | Tuple.append(tuple, :john) # appends an item to tuple
134 | ```
135 | 
136 | ## Maps
137 | 
138 | Map is a collection of key-value pairs.
139 | 
140 | ```elixir
141 | map = %{1 => :one, 2 => :two, 3 => :three, 4 => :four, 5 => :five}
142 | ```
143 | 
144 | ## Functions
145 | 
146 | Function is a sub-routine which contains set of statements. 
147 | 
148 | 1. Anonymous Functions:
149 | 
150 | Anonymous functions are functions with no name and they use  `fn..end` constructs.
151 | 
152 | 2. Named functions:
153 | 
154 | Assign names to functions so that they can be called easily. Always named functions are defined in modules.
155 | 
156 | ```elixir
157 | defmodule ModuleName do
158 |   def function_name(parameter1, parameter2) do
159 |     #code 
160 |   end
161 | end
162 | ```
163 | 


--------------------------------------------------------------------------------
/erlang.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Erlang 
 3 | description: Erlang cheatsheet gives you a quick reference to code syntax with examples makes it handy while coding.
 4 | created: 2020-07-02
 5 | updated: 2020-07-02
 6 | ---
 7 | 
 8 | ## Sample program
 9 | 
10 | ```c
11 | -module(helloworld).
12 | -export([start/0]).
13 | start() ->
14 | 		io:fwrite("Hello World!").
15 | ```
16 | * **module** : It is used to add a namespace like in other programming language. 
17 | * **export** : Any function which is defined in the program can be used by using export function. `/0` means that `start` function accepts 0 parameters.
18 | * **start()** : start() is a function
19 | * **io** : io is an module which has io all the required Input and Output functions.
20 | * **fwrite** : to output data to the console.
21 | * **%** : Used to provide comments
22 | 
23 | ## Variables
24 | Variables syntax is as follows
25 | 
26 | ```c
27 | variable-name = value
28 | ```
29 | ## Data types
30 | 
31 | | Data type| Usage| Description|
32 | |----|----|----|
33 | | Numeric| start() -> `io:fwrite("~w",[10+10])`. | Erlang supports both integer and float values.|
34 | | Atom| start() -> io:fwrite(true) | Atoms should start with lower case leters and can contain  lowercase and uppercase characters, numbers, `_` and `@`. You can also put atom in single quotes|
35 | | Boolean | start() ->  io:fwrite(10 =< 8)| Output will be either true or false based on the values given|
36 | | Bit String|  str = <<10,20>>| Strings are enclosed in << >> and are used to store untyped memory|
37 | | Lists| `[1,2,3]`| Lists is a compound data type with Variable number of elements.|
38 | | Tuples| t = {apple, 100, {orange,50}} | Tuple is a compound data type with fixed number of elements.|
39 | |Map| map = #{name=>onecompiler,message=>Learning}| Map is a compound data type with a variable number of key-value pairs|
40 | 
41 | ## Operators
42 | | Operator type | Description|
43 | |----|-----|
44 | | Arithmetic Operator|+ , - , * , / , rem, div|
45 | | Relational Operator| < , > , <= , >=, /= , ==|
46 | | Logical Operator| and, or, not, xor |
47 | | Bitwise Operator | band, bor, bnot, bxor|
48 | 
49 | ## Conditional Statements
50 | 
51 | ### 1. If-Else
52 | 
53 | ```c
54 | if
55 | condition ->
56 |    true-statement;
57 | true ->
58 |    false-statement
59 | end.
60 | ```
61 | 
62 | ### 2. Case
63 | 
64 | ```c
65 | case value of
66 |    value1 -> statement1;
67 |    value2 -> statement2;
68 |    valuen -> statementn
69 | end.
70 | ```
71 | ### Note:
72 | As Erlang is a functional programming language, there are no direct constructs for while, for and other loops. Recursion is the technique followed to implement loops in Erlang. 
73 | 
74 | ## Function
75 | 
76 | ### Defining a function
77 | ```c
78 | FunctionName(Pattern1… PatternN) ->
79 | %code
80 | ```
81 | ### Calling a function
82 | ```c
83 | FunctionName(Pattern1… PatternN)
84 | ```
85 | 


--------------------------------------------------------------------------------
/es2csv.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: es2csv
 3 | description: es2csv is a library written in python which provides command line utility to export documents based on query from elasticsearch to csv.
 4 | created: 2019-08-19
 5 | updated: 2019-08-19
 6 | ---
 7 | 
 8 | es2csv is a library written in python which provides command line utility to export documents based on query from elasticsearch to csv.
 9 | 
10 | ## Installation
11 | ```sh
12 | pip install git+https://github.com/taraslayshchuk/es2csv.git   #install from git source
13 | pip install es2csv                                             #install using pip
14 | ```
15 | 
16 | ## Query and save results to file
17 | ```sh
18 | es2csv -q 'company: volkswagen' -o cars.csv    #documents matching query string will be saved to cars.csv file
19 | ```
20 | 
21 | ## Export required fields
22 | ```sh
23 | es2csv -f model releaseYear mileage -q 'company: volkswagen' -o cars.csv  #only specified fields like model,releaseYear and mileage will be saved to file
24 | ```
25 | 
26 | ## Authorization
27 | ```sh
28 | es2csv -a username:password -u http://onecompiler:9001/cars/ -q 'company: volkswagen' -o cars.csv
29 | ```
30 | 
31 | ## More options with examples  
32 | 
33 | | Arguments | Description  | Default Value | Example Command |
34 | |--------|--------|--------|--------|
35 | |-u, --url| Elasticsearch host url | `http://localhost:9200` | es2csv -u `http://onecompiler:9001/cars/` -q 'company: volkswagen' -o cars.csv |
36 | |-i, --index-prefixes|Index name prefix| logstash-* | es2csv -i cars -q 'company: volkswagen' -o cars.csv|
37 | |-t, --tags|Query tags, can add more than 1 tag| | es2csv -t dev -q 'company: volkswagen' -o cars.csv|
38 | |-d, --delimiter|Provide delimiter to be used in csv file| , | es2csv -d ':' -q 'company: volkswagen' -o cars.csv|
39 | |-m, --max|Max results to be written in file| 0 | es2csv -m 100 -q 'company: volkswagen' -o cars.csv|
40 | |-r, --raw-query|Can write query in Query DSL format| | es2csv -r -q '{"query": {"match": {"company": "volkswagen"}}}' -o cars.csv|
41 | |--debug|Switches debug mode on| | |
42 | |-h, --help|Shows help message| | |
43 | 


--------------------------------------------------------------------------------
/express.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: express (Javascript Library)
  3 | description: Express is a minimal and flexible NodeJS web application framework. Express is the most popular web application framework in the NodeJS echosystem.
  4 | created: 2019-06-24
  5 | updated: 2022-10-01
  6 | color: #636e72
  7 | ---
  8 | 
  9 | 
 10 | Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.
 11 | 
 12 | ## Installation
 13 | 
 14 | ```sh
 15 | npm install express
 16 | ```
 17 | 
 18 | ## Hello World server
 19 | 
 20 | ```javascript
 21 | const express = require('express');
 22 | const app = express();
 23 | 
 24 | app.set('port', (process.env.PORT || config.port));
 25 | 
 26 | app.get('/', (req, res) => res.send('Hello World!'));
 27 | 
 28 | app.listen(app.get('port'), () => console.log(`Server started on ${app.get('port')} port`))
 29 | ```
 30 | 
 31 | ## Basic routing
 32 | 
 33 | ```javascript
 34 | //GET
 35 | app.get('/', function (req, res) {
 36 |   res.send('Hello World!')
 37 | })
 38 | 
 39 | //POST 
 40 | app.post('/', function (req, res) {
 41 |   res.send('POST request. body:', req.body)
 42 | })
 43 | 
 44 | //DELETE
 45 | app.delete('/:id', function (req, res) {
 46 |   res.send('DELETE request for id:'. req.params.id)
 47 | })
 48 | ```
 49 | 
 50 | ## Static files serving
 51 | 
 52 | ```javascript
 53 | app.use(express.static(__dirname + '/public'));
 54 | ```
 55 | 
 56 | ## logging all routes
 57 | ```javascript
 58 | app._router.stack.forEach(function(r) {
 59 |     if (r.route && r.route.path) {
 60 |       console.log(r.route.path)
 61 |     }
 62 |   });
 63 | ```
 64 | 
 65 | ## defining routes in a different file
 66 | 
 67 | #### `/routes/users.js` file
 68 | 
 69 | ```javascript
 70 | // File Path: /routes/users.js
 71 | 
 72 | var express = require('express');
 73 | var router = express.Router();
 74 | 
 75 | router.get('/', (req, res) => {
 76 |     const users = []; // get from db
 77 |     res.send(users);
 78 | });
 79 | 
 80 | router.get('/:id', (req, res)=> {
 81 |     const user = {}; // get from db
 82 |     res.send(user);
 83 | });
 84 | 
 85 | router.post('/', (req, res) => {
 86 |     const user = req.body; // save user to db
 87 |     res.send({status: 'success'});
 88 | });
 89 | 
 90 | module.exports = router;
 91 | ```
 92 | 
 93 | #### adding routes from `/routes/users.js`
 94 | ```javascript
 95 | app.use('/user', require('./routes/user'));
 96 | ```
 97 | 
 98 | ## Redirects
 99 | 
100 | ```javascript
101 | router.get('/old-path', function(req, res) {
102 |   res.redirect('/temp-new-path'); // sends a 302
103 | });
104 | 
105 | router.get('/old-path', function(req, res) {
106 |   res.redirect(301, '/permanent-new-path'); // sends a 301
107 | });
108 | ```
109 | 


--------------------------------------------------------------------------------
/figma.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: figma (design tool)
 3 | description: figma is a cloud-based design tool that is similar to Sketch in functionality and features, but with big differences that make figma better for team collaboration.figma works on any operating system that runs a web browser. Macs, Windows PCs, Linux machines, and even Chromebooks can be used with figma. It is the only design tool of its type that does this, and in shops that use hardware running different operating systems, everyone can still share, open, and edit figma files.
 4 | created: 2022-10-26
 5 | updated: 2022-10-26
 6 | 
 7 | ---
 8 | ---
 9 | ### 1.  OBJECT
10 | ---
11 | 
12 | | TOOL    |        SHORTCUT |
13 | | ---------------|----------|
14 | | Rectangle tool |        R |
15 | | Ellipse tool   |       O  |
16 | | Line tool      |        L |
17 | | Pen tool       |        P |
18 | | Frame tool     |        F |
19 | | Copy           |      ctrl+c |
20 | | Cut            |      ctrl+x |
21 | | Paste          |      ctrl+v |
22 | | Duplicate      |      ctrl+drag |
23 | | Group Selection|       ctrl+G |
24 | | Ungroup        |      ctrl+shift+G |
25 | | Toggle visibility  |   ctrl+shift+H |
26 | | Toggle Lock      |    ctrl+shift+T |
27 | 
28 | ***
29 | ### 2.  VIEW
30 | ---
31 | |VIEW       |         SHORTCUT |
32 | |------------|------------------|
33 | |Navigate    |        space+drag|
34 | |Zoom in     |         +        | 
35 | |Zoom out    |         -        |
36 | |Show/Hide Rulers|    Shift+R   |
37 | |Show/Hide Layouts|   ctrl+G    |
38 | |Zoom to 100% |       Shift+0   |
39 | |Show Outlines |       Ctrl+Shift+3 |
40 | |Pixel Preview |      Ctrl+Alt+Y  |
41 | 
42 | ***
43 | 
44 | ### 3.  TEXT
45 | ---
46 | 
47 | |TEXT|                 SHORTCUT|
48 | |----|-------------------------|
49 | |Type tool|             T|
50 | |Toggle Underline|      ctrl+u|
51 | |Toggle Italic|         crtl+I|
52 | |Toggle Bold|           ctrl+B|
53 | |Paste and Match Style| Ctrl+Shift+V|
54 | ***
55 | 
56 | ### 4.  FILE & PROPERTIES
57 | ---
58 | 
59 | |PROPERTIES|                        SHORTCUT|
60 | |----------|--------------------------------|
61 | |Place Image|                       Ctrl+Shift+K|
62 | |Save to Version History|           Ctrl+Alt+S|
63 | |Export|                            Ctrl+Shift+E|
64 | ***
65 | 
66 | 
67 |  ### 5. Frequently Used
68 |  ---
69 | 
70 |  |PROPERTIES|              SHORTCUT|
71 |  |----------|----------------------|
72 | |Collapse all layers|       Alt+L|
73 | |Switch to layers Panel|    Alt+1|
74 | |Switch to Assets Panel|    Alt+2|
75 | |Command UI|                ctrl+/|
76 | |Add Auto Layout|           Shift+A|


--------------------------------------------------------------------------------
/find.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: find Linux Command
 3 | description: find Linux Command is used to locate files in directories. By default find looks for files in current directory.
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | find Linux Command is used to locate files in directories. By default find looks for files in current directory.
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | find [option(s)] [Path] [expression]
15 | ```
16 | 
17 | |Option|Description|
18 | |---|---|
19 | |-P| Not follow symbolic links (default behaviour) |
20 | |-L|Follow symbolic links|
21 | |-H|Follow symbolic links only while processing command line arguments|
22 | 
23 | ## Examples
24 | 
25 | Consider the following directory structure 
26 | 
27 | ```sh
28 | $ tree
29 | .
30 | ├── images
31 | │   ├── cat.png
32 | │   ├── dog.png
33 | │   ├── moon.png
34 | │   └── sun.png
35 | ├── movies
36 | │   ├── action
37 | │   │   ├── bar.mp4
38 | │   │   └── foo.mp4
39 | │   └── comedy
40 | ├── music
41 | │   ├── song1.mp3
42 | │   └── song2.mp3
43 | └── readme.txt
44 | 
45 | 5 directories, 9 files
46 | ```
47 | 
48 | ```
49 | find . -name cat.png
50 | ./images/cat.png
51 | ```
52 | 
53 | ```
54 | find . -name cat*
55 | ./images/cat.png
56 | ```
57 | 
58 | ```
59 | find . -name *.png
60 | ./images/dog.png
61 | ./images/moon.png
62 | ./images/cat.png
63 | ./images/sun.png
64 | ```


--------------------------------------------------------------------------------
/fortran.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Fortran
  3 | description: Fortran cheatsheet contains useful code syntax with examples which is really handy while coding.
  4 | created: 2020-06-29
  5 | updated: 2020-06-29
  6 | ---
  7 | 
  8 | ## Sample program
  9 | 
 10 | ```fortran
 11 | program hello
 12 |   character :: name
 13 |   read *, name
 14 |   print *, "Hello ", name
 15 | end program hello
 16 | ```
 17 | * **program** : All Fortran programs start with the keyword `program` followed by program name
 18 | * **character :: name** : declaring a character variable named name
 19 | * **read** : to read the data from console
 20 | * **print** : to display the data to console
 21 | * **end program** : All Fortran programs end with the keyword `end program` followed by program name
 22 | * **!** : Comment
 23 | 
 24 | ## Data Types
 25 | 
 26 | | Data type | Description | Usage|
 27 | |-----|-----|-----|
 28 | |Integer | To store integer variables|integer :: x|
 29 | |Real | To store float values | real :: x|
 30 | |Complex | To store complex numbers| complex :: x,y|
 31 | |Logical | To store boolean values True or false| logical :: x=.True. , logical :: x = .FALSE.|
 32 | |Character| To store characters and strings | character :: x|
 33 | 
 34 | ## Variables
 35 | 
 36 | ```
 37 | data type :: variable_name
 38 | ```
 39 | ### Example
 40 | 
 41 | ```fortran
 42 |    ! declaring variables
 43 |    integer :: marks      ! Integer variable
 44 |    character(len=30) :: name ! string variable of length 30 characters
 45 |    
 46 |    !assigning values to variables
 47 |    marks = 60
 48 |    name = "Foo"  
 49 | ```
 50 | ## Derived Data types
 51 | 
 52 | ```fortran
 53 | !Type Declaration
 54 |    type typeName      
 55 |       !declarations
 56 |    end type typeName
 57 | 
 58 | !Declaring type variables
 59 |    type(typeName) :: type-varName
 60 | 
 61 | !accessing the components of the derived type
 62 |    
 63 |    type-varName%type-declaration-variable = value
 64 | ```
 65 | ## Operators
 66 | 
 67 | | Operator type | Description|
 68 | |----|-----|
 69 | | Arithmetic Operator|+ , - , * , / , **|
 70 | | Relational Operator| < , > , <= , >=, /= , ==|
 71 | | Logical Operator| .and. , .or. , .not. , .eqv. , .neqv.|
 72 | 
 73 | ## Arrays
 74 | 
 75 | ### Syntax
 76 | 
 77 | ```fortran
 78 | data-type, dimension (x,y) :: array-name
 79 | ```
 80 | 
 81 | ### Example
 82 | ```fortran
 83 | integer, dimension(3,3) :: cube
 84 | ```
 85 | ## Conditional Statements
 86 | ### 1. If
 87 | 
 88 | ```fortran
 89 | if (logical-expression) then      
 90 |    !Code  
 91 | end if
 92 | ```
 93 | 
 94 | ### 2. If-Else
 95 | 
 96 | ```fortran
 97 | if (logical-expression) then     
 98 |    !code when the condition is true
 99 | else
100 |    !code when the condition fails
101 | end if
102 | ```
103 | 
104 | ### 3. Case
105 | 
106 | ```fortran
107 | [name:] select case (regular-expression) 
108 |    case (value1)          
109 |    ! code for value 1          
110 |    ... case (value2)           
111 |    ! code for value 2           
112 |    ...       
113 |    case default          
114 |    ! default code          
115 |    ...   
116 | end select [name]
117 | ```
118 | 
119 | ## Loops
120 | 
121 | ### 1. Do
122 | 
123 | ```fortran
124 | do i = start, stop [,step]    
125 |    ! code
126 | end do
127 | ```
128 | ### 2. Do-While
129 | 
130 | ```fortran
131 | do while (condition) 
132 |    !Code
133 | end do
134 | ```
135 | 
136 | ## Function
137 | 
138 | A function is a procedure which returns a single value. 
139 | 
140 | ```fortran
141 | function functionName(arguments)  
142 |   ! code 
143 | end function [functionName]
144 | ```
145 | ### Calling a function
146 | ```fortran
147 | functionName(arguments)  
148 | ```
149 | ## Sub-routines
150 | 
151 | Subroutine is a procedure which does not return a value.
152 | 
153 | ```fortran
154 | subroutine name(arguments)
155 |   ! code  
156 | end subroutine [name]
157 | ```
158 | 
159 | ### Calling a Sub-routine
160 | ```fortran
161 | call subroutineName(arguments)  
162 | ```
163 | 


--------------------------------------------------------------------------------
/fsharp.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: F#
  3 | description: F# Programming language cheatsheet contains useful code syntax with examples which is handy while coding.
  4 | created: 2020-06-27
  5 | updated: 2020-06-27
  6 | ---
  7 | 
  8 | ## Sample program
  9 | 
 10 | ```fs
 11 | open System
 12 | let name = Console.ReadLine()
 13 | Console.Write("Hello 0.\n", name)         
 14 | ```
 15 | * **open** : used to import namespaces
 16 | * **let** : used to declare a variable. 
 17 | * **Console.ReadLine()** : to read input data from console
 18 | * **Console.Write()** : prints output data to the console
 19 | * **`//`** : single line comment
 20 | * `(*` Multi
 21 | 
 22 |     Line
 23 | 
 24 |     comments `*)`
 25 | 
 26 | F# does not have any specific entry point, F# compiler executes all the statements from top to bottom.
 27 | 
 28 | ## Data Types
 29 | 
 30 | ### Integer Data types
 31 | | Data type | Description | Size|Range|
 32 | |-----|-----|-----|----|
 33 | |sbyte|8-bit signed integer|1 byte|-128 to 127|
 34 | |byte|8-bit unsigned integer|1 byte|0 to 255|
 35 | |int16|16-bit signed integer|2 bytes|-32768 to 32767|
 36 | |unit16|16-bit unsigned integer|2 bytes|0 to 65,535|
 37 | |int/int32|32-bit signed integer|4 bytes|-2,147,483,648 to 2,147,483,647|
 38 | |uint32|32-bit unsigned integer|4 bytes|0 to 4,294,967,295|
 39 | |int64|64-bit signed integer|8 bytes|	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807|
 40 | |uint64|64-bit unsigned integer|8 bytes|0 to 18,446,744,073,709,551,615|
 41 | |bigint|arbitrary precision integer|At least 4 bytes|Integers|
 42 | 
 43 | ### Float Data types
 44 | | Data type | Description | Size|Range|
 45 | |-----|-----|-----|----|
 46 | |float32|32-bit signed floating point number|4 bytes|±1.5e-45 to ±3.4e38|
 47 | |float|64-bit signed floating point number|8 bytes|	±5.0e-324 to ±1.7e308|
 48 | |decimal|128-bit signed floating point number|16 bytes|±1.0e-28 to ±7.9e28|
 49 | 
 50 | ### Text and Boolean Data types
 51 | | Data type | Description | Size|Range|
 52 | |-----|-----|-----|----|
 53 | |char|single character|2 bytes|U+0000 to U+ffff|
 54 | |string|Text|20 + (2 * length of the string) bytes| 0 to up to 2 billion characters|
 55 | |bool|Stores either true or false|1 byte|True or false|
 56 | 
 57 | ## Variables
 58 | 
 59 | ```javascript
 60 | let variable_name:data-type = value
 61 | ```
 62 | ### Mutable variable declaration
 63 | 
 64 | ```javascript
 65 | let mutable variable_name:data-type = value
 66 | ```
 67 | ## Operators
 68 | 
 69 | | Operator type | Description|
 70 | |----|-----|
 71 | | Arithmetic Operator|+ , - , * , / , %, **|
 72 | | comparision Operator| < , > , <= , >=, <> , ==|
 73 | | Bitwise Operator| &&& , ^^^ , \|\|\|, ~~~, <<<, >>>|
 74 | | Boolean Operator| && , `\|\|`, not |
 75 | 
 76 | ## List
 77 | 
 78 | List is an ordered, immutable set of elements of the same type.
 79 | 
 80 | Lists can be defined in mutiple ways:
 81 | ```javascript
 82 | let list1 = [1; 2; 3; 4; 5 ]
 83 | 
 84 | //or
 85 | 
 86 | let list2 = 1::2::3::4::5::[];;
 87 | 
 88 | // or
 89 | 
 90 | let list3 = [1:5] 
 91 | ```
 92 | ## Tuples
 93 | 
 94 | Tuples are collection of data of the same or different types.
 95 | 
 96 | ```c
 97 | let directions =( "east", "west", "north", "south" ) // tuple of string type
 98 | let info = ( "foo", 123, true) // tuple of mixed types
 99 | ```
100 | 
101 | ## Maps
102 | 
103 | Map is a collection of key-value pairs.
104 | 
105 | ```c
106 | Map.empty. (* Creating an empty Map *)
107 |       Add("India", "Hindi").
108 |       Add("US", "English").
109 |       Add("France", "French").
110 |       Add("Japan", "Japanese");
111 | ```
112 | 
113 | ## Conditional Statements
114 | 
115 | ### 1. If
116 | ```java
117 | if conditional-expression then
118 |    // code
119 | ```
120 | ### 2. If-Else
121 | ```java
122 | if conditional-expression then
123 |    // code
124 | else 
125 |    // code
126 | ```
127 | ### 3. Nested If-Else
128 | 
129 | ```java
130 | if conditional-expression then
131 |   // code
132 | elif conditional-expression then
133 |    // code
134 | elif conditional-expression then
135 |    // code
136 | ...
137 | else
138 |    // code
139 | ```
140 | 
141 | ## Loops
142 | 
143 | ### 1. For
144 | 
145 | #### For..to
146 | Iteration occurs in ascending order.
147 | 
148 | ```java
149 | for var = start-expression to end-expression do
150 |   // code  
151 | ```
152 | 
153 | #### For...down-to
154 | Iteration occurs in descending order.
155 | 
156 | ```java
157 | for var = start-expression downto end-expression do
158 |   // code  
159 | ```
160 | #### For..in
161 | 
162 | ```java
163 | for pattern in enumerable-collection-expr do
164 |    // code
165 | ```
166 | 
167 | ### Example
168 | ```javascript
169 | let listItems = [1,2,3,4,5]
170 | for x in listItems do
171 |    printfn "%d" x
172 | ``` 
173 | 
174 | ### 2. While
175 | 
176 | ```java
177 | while condition-expr do   
178 |  // code 
179 | ```
180 | 
181 | ## Function
182 | 
183 | ### How to define a function
184 | 
185 | ```javascript
186 | let [inline] function-name parameter-list [ : return-type ]
187 |    = function-body
188 | ```
189 | 
190 | ### How to call a function
191 | 
192 | ```javascript
193 | let Var = function-name parameter-list
194 | ```


--------------------------------------------------------------------------------
/google-analytics.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Google Analytics
 3 | description: Google Analytics lets you measure your end user interactions on your websites and mobile apps. Google Analytics records all interactions and provides meaningful insights.
 4 | created: 2019-10-25
 5 | updated: 2019-10-25
 6 | ---
 7 | 
 8 | Google Analytics lets you measure your end user interactions on your websites and mobile apps. Google Analytics records all interactions and provides meaningful insights.
 9 | 
10 | ## Available Platforms
11 | 
12 | 1. Web
13 | 2. Android
14 | 3. iOS
15 | 
16 | ## Adding Google Analytics to your Web application
17 | Google analytics can be added to web applications by including the following script in head tag.
18 | 
19 | ```javascript
20 | <!-- Google Analytics-->
21 | <script>
22 |   (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
23 |     (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
24 |       m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
25 |   })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
26 | 
27 |   ga('create', 'UA-xxxxx-x', 'auto');
28 |   ga('send', 'pageview');
29 | </script>
30 | 
31 | ```
32 | 
33 | ## Adding Google Analytics to your Android application
34 | 
35 | #### 1. Add `google-services` to your `build.gradle`
36 | 
37 | ```groovy
38 | dependencies {
39 |   classpath 'com.google.gms:google-services:3.0.0'
40 | }
41 | ```
42 | 
43 | #### 2. Add `play-services-analytics` to your `app/build.gradle`
44 | 
45 | ```groovy
46 | dependencies {
47 |   compile 'com.google.android.gms:play-services-analytics:10.2.4'
48 | }
49 | ```
50 | 
51 | #### 3. Create `app/src/res/xml/global_tracker.xml` to configure your Google Analytics tracker id
52 | 
53 | ```xml
54 | <?xml version="1.0" encoding="utf-8"?>
55 | <resources>
56 |   <string name="ga_trackingId" translatable="false">UA-xxxxx-x</string>
57 | </resources>
58 | ```
59 | 
60 | #### 4. Create `AnalyticsApplication` by extending `android.app.Application` 
61 | 
62 | ```java
63 | package com.foo;
64 | import android.app.Application;
65 | import com.google.android.gms.analytics.GoogleAnalytics;
66 | import com.google.android.gms.analytics.Tracker;
67 | 
68 | public class AnalyticsApplication extends Application {
69 |   private static GoogleAnalytics googleAnalytics;
70 |   private static Tracker tracker;
71 | 
72 |   @Override
73 |   public void onCreate() {
74 |     super.onCreate();
75 |     googleAnalytics = GoogleAnalytics.getInstance(this);
76 |   }
77 | 
78 |   synchronized public Tracker getDefaultTracker() {
79 |     if (tracker == null) {
80 |       tracker = googleAnalytics.newTracker(R.xml.global_tracker);
81 |     }
82 |     return tracker;
83 |   }
84 | }
85 | ```
86 | 
87 | #### 5. Start tracking your activities
88 | 
89 | ```java
90 | AnalyticsApplication application = (AnalyticsApplication) getApplication();
91 | tracker = application.getDefaultTracker();
92 | tracker.setScreenName("HomePage");
93 | tracker.send(new HitBuilders.ScreenViewBuilder().build());
94 | ```
95 | 


--------------------------------------------------------------------------------
/google-nexus-screen-resolutions.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Google Nexus screen resolutions
 3 | description: Google Nexus screen resolutions for developers. 
 4 | created: 2019-08-19
 5 | updated: 2022-10-03
 6 | color: #636e72
 7 | ---
 8 | 
 9 | | Device Model | Screen Resolution (Pixels) | Screen Size (Inches) | 
10 | |:------------:|:-------------------------:|:--------------------:|
11 | |Nexus 6P|2560 x 1440|5.7"|
12 | |Nexus 5X|1920 x 1080|5.2"|
13 | |Nexus 6|1440 x 2560|5.96"|
14 | |Nexus 5|1920 x 1080|4.95"|
15 | |Nexus 4|1280 x 768|4.7"|
16 | |Galaxy Nexus|1280 x 720|4.65"|
17 | |Nexus S|800 x 480|4"|
18 | |Nexus One|800 x 480|3.7"|
19 | 


--------------------------------------------------------------------------------
/google-pixel-screen-resolutions.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Google Pixel screen resolutions
 3 | description: Google Pixel screen resolutions for developers. 
 4 | created: 2019-08-19
 5 | updated: 2022-10-03
 6 | color: #636e72
 7 | ---
 8 | 
 9 | | Device Model | Screen Resolution(Pixels) | Screean Size(Inches) | 
10 | |:------------:|:-------------------------:|:--------------------:|
11 | |Google Pixel 6a|2400 x 1080|6.1"|
12 | |Google Pixel 6 Pro|3120 x 1440|6.7"|
13 | |Google Pixel 6|2400 x 1080|6.4"|
14 | |Google Pixel 5a|2400 x 1080|6.34"|
15 | |Google Pixel 5|2340 x 1080|6.0"|
16 | |Google Pixel 4a (5G)|2340 x 1080|6.2"|
17 | |Google Pixel 4a|2340 x 1080|5.8"|
18 | |Google Pixel 4 XL|3040 x 1440|6.3"|
19 | |Google Pixel 4|2280 x 1080|5.7"|
20 | |Google Pixel 3a XL|2160 x 1080|6.0"|
21 | |Google Pixel 3a|2220 x 1080|5.6"|
22 | |Google Pixel 3 XL|2960 x 1440|6.3"|
23 | |Google Pixel 3|2160 x 1080|5.5"|
24 | |Google Pixel 2 XL|1440 x 2880|6.0"|
25 | |Google Pixel 2|1080 x 1920|5.0"|
26 | |Google Pixel XL|1440 x 2560|5.5"|
27 | |Google Pixel|1080 x 1920|5.0"|
28 | 


--------------------------------------------------------------------------------
/grep.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: grep Linux Command
 3 | description: grep is a Linux command line utility to search plain text datasets using regular expressions. 
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | grep is a Linux command line utility to search plain text datasets using regular expressions. 
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | grep [options] search-pattern [file(s)]
15 | ```
16 | 
17 | ## Examples
18 | 
19 | Lets take following file as an example to perform grep operations
20 | 
21 | ```sh
22 | $ cat readme.txt
23 | Hello World line1
24 | Hello World line2
25 | Hello World line3
26 | Hello World line4
27 | Hello World line5
28 | 
29 | ```
30 | 
31 | ```sh
32 | $ grep 5 readme.txt
33 | Hello World line5
34 | ```
35 | 
36 | ```sh
37 | $ grep line4 readme.txt
38 | Hello World line4
39 | ```
40 | 
41 | ```sh
42 | $ grep Hello readme.txt
43 | Hello World line1
44 | Hello World line2
45 | Hello World line3
46 | Hello World line4
47 | Hello World line5
48 | ```
49 | 
50 | ```sh
51 | $ grep -i hello readme.txt
52 | Hello World line1
53 | Hello World line2
54 | Hello World line3
55 | Hello World line4
56 | Hello World line5
57 | ```
58 | 
59 | ```
60 | Note: -i is to ignore case
61 | ```


--------------------------------------------------------------------------------
/groovy-http-calls.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Groovy Http calls
 3 | description: Example GET, POST Http calls in Groovy with out using any special library
 4 | created: 2019-08-14
 5 | updated: 2019-08-14
 6 | color: #286b86
 7 | ---
 8 | 
 9 | Example GET, POST Http calls in Groovy with out using any special library
10 | 
11 | ## GET Calls
12 | 
13 | ```java
14 | def get = new URL("https://httpbin.org/get").openConnection(); 
15 | 
16 | def postResponseCode = get.getResponseCode();
17 | def postResponseData = get.getInputStream().getText();
18 | 
19 | println "Response Code: ${postResponseCode}"
20 | println "Response Data: ${postResponseData}"
21 | ```
22 | Fork code: https://onecompiler.com/groovy/3ux954nea
23 | 
24 | ## POST Calls
25 | 
26 | ```java
27 | def post = new URL("https://httpbin.org/post").openConnection(); 
28 | def body = 
29 | '''
30 | {
31 |   "foo" : "bar",
32 |   "age" : 20
33 | }
34 | '''
35 | 
36 | post.setRequestMethod("POST")
37 | post.setDoOutput(true)
38 | post.setRequestProperty("Content-Type", "application/json")
39 | post.getOutputStream().write(body.getBytes("UTF-8"));
40 | 
41 | def postResponseCode = post.getResponseCode();
42 | def postResponseData = post.getInputStream().getText();
43 | 
44 | println "Response Code: ${postResponseCode}"
45 | println "Response Data: ${postResponseData}"
46 | ```
47 | Fork code: https://onecompiler.com/groovy/3ux94sz4p


--------------------------------------------------------------------------------
/gson.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Gson (Java Library)
 3 | description: Gson is a Java Library which is used to convert Java Objects to JSON strings and back. Gson library provides toJson() and fromJson() methods using which users can serialize /deserialize Java objects to and back from JSON Strings
 4 | created: 2019-06-25
 5 | updated: 2019-06-25
 6 | color: #0984e3
 7 | ---
 8 | 
 9 | Gson is a Java Library which is used to convert Java Objects to JSON strings and back. Gson library provides `toJson()` and `fromJson()` methods using which users can serialize /deserialize Java objects to and back from JSON Strings.
10 | 
11 | ## Installation
12 | #### Maven
13 | ```xml
14 | <!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
15 | <dependency>
16 |     <groupId>com.google.code.gson</groupId>
17 |     <artifactId>gson</artifactId>
18 |     <version>2.8.5</version>
19 | </dependency>
20 | ```
21 | #### Gradle
22 | ```groovy
23 | // https://mvnrepository.com/artifact/com.google.code.gson/gson
24 | compile group: 'com.google.code.gson', name: 'gson', version: '2.8.5'
25 | ```
26 | 
27 | 
28 | ## Java Object to JSON String
29 | ```java
30 | import java.util.Arrays;
31 | import java.util.HashMap;
32 | import java.util.Map;
33 | 
34 | import com.google.gson.Gson;
35 | 
36 | public class GsonObjectToJSONExample {
37 |     public static void main(String[] args) {
38 | 
39 |         Gson gson = new Gson();
40 | 
41 |         Map<String, Object> javaObject = new HashMap<>();
42 | 
43 |         javaObject.put("aNumber", 1);
44 |         javaObject.put("aString", "foo");
45 |         javaObject.put("aBoolean", true);
46 |         javaObject.put("aList", Arrays.asList("red", "green", "blue"));
47 | 
48 |         String jsonString = gson.toJson(javaObject);
49 | 
50 |         System.out.println(jsonString);
51 | 
52 |     }
53 | }
54 | ```
55 | ### Output: 
56 | ```json
57 | {"aNumber":1,"aBoolean":true,"aString":"foo","aList":["red","green","blue"]}
58 | ```
59 | 
60 | ## JSON String to Java Object
61 | ```java
62 | import java.util.Map;
63 | 
64 | import com.google.gson.Gson;
65 | 
66 | public class GsonJsonToObjectExample {
67 |     public static void main(String[] args) {
68 | 
69 |         Gson gson = new Gson();
70 |         String jsonString = "{\"aNumber\":1,\"aBoolean\":true,\"aString\":\"foo\",\"aList\":[\"red\",\"green\",\"blue\"]}";
71 | 
72 |         Map javaObject = gson.fromJson(jsonString, Map.class);
73 | 
74 |         System.out.println("aList: " + javaObject.get("aList"));
75 |         System.out.println("aNumber: " + javaObject.get("aNumber"));
76 | 
77 |     }
78 | }
79 | ```
80 | ### Output: 
81 | ```sh
82 | aList: [red, green, blue]
83 | aNumber: 1.0
84 | ```


--------------------------------------------------------------------------------
/haskell.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Haskell
  3 | description: Quick reference to Haskell cheat sheet which will increase your productivity as it contains useful syntax and is very handy while coding. 
  4 | created: 2020-06-25
  5 | updated: 2020-06-25
  6 | ---
  7 | 
  8 | ## Sample program
  9 | 
 10 | ```java
 11 | main = do  
 12 |     name <- getLine  
 13 |     putStrLn ("Hello " ++ name ++ ", Happy learning!")
 14 | ```
 15 | * ***main*** : entry point of the program
 16 | * ***getLine*** : reads input data from Console
 17 | * ***putStrLn*** : prints data to the console.
 18 | * `--` : Single line comment
 19 | * `{-` Multi
 20 | 
 21 |     Line
 22 | 
 23 |     comment `-}`
 24 | 
 25 | ## Data types
 26 | 
 27 | | Data-type | Description |
 28 | |----|----|
 29 | |Numbers| Haskell is intelligent to identify numbers without specifying data type|
 30 | |Characters| Haskell is intelligent to identify characters and strings without specifying data type|
 31 | |Tuple|To declare multiple values in a single data type. Tuples are represented in single paranthesis. For example (10,20,'apple')|
 32 | |Boolean|To represent boolean values, true or false|
 33 | |List|To declare same type of values in a single data type. Lists are represented in square braces.For example `[1,2,3]` or `['a','b','c','d']|
 34 | 
 35 | ## Reserved keywords
 36 | 
 37 | ||||
 38 | |----|----|----|----|
 39 | | case | class | data| deriving| 
 40 | | do | else | if |import|
 41 | | in | infix | infixl | infixr|
 42 | | instance | let | of | module|
 43 | | newtype | then | type | where
 44 | 
 45 | ## Operators
 46 | 
 47 | |Type|Operators|
 48 | |----|----|
 49 | | Arithmetic Operators| + , - , * , / , % , **, &&, \|\|, not |
 50 | | Comparision Operators| == , /= , > , >= , < , <= |
 51 | | Bitwise Operators| & , ^ , \| , ^ , ~ , << , >> , >>>|
 52 | | Function Operators| \, ., \||
 53 | | List Operators | \[...,...\], ++, :, !!, .. , \\, <-|
 54 | | Monad Operators| :, ->, ::, =>, (), >>, >>=, >@>,(..)|
 55 | | Pattern Operators | _, ~, !, @|
 56 | 
 57 | ## Conditional Statements
 58 | 
 59 | ###  If-Else 
 60 | 
 61 | ```java
 62 | if conditional-expression
 63 |   then true statements 
 64 |   else false statements
 65 | ```
 66 | ### Case
 67 | ```java
 68 |  case exp of
 69 |      Pattern1  -> action1
 70 |      Pattern2  -> action2
 71 |      _         -> else_action
 72 | ```
 73 | 
 74 | ## Tuples
 75 | 
 76 | Tuples are used to group data of different types(similar type is also allowed)
 77 | 
 78 | ```java
 79 | (item1,item2,[itemn…])
 80 | ```
 81 | ### Example
 82 | ```java
 83 | (1, "John", 35.2, true)
 84 | ```
 85 | ## Lists
 86 | 
 87 | Lists are usually used to group data of similar types
 88 | ```java
 89 | [item1, item2,[itemn]]
 90 | ```
 91 | ### Example
 92 | 
 93 | ```java
 94 | [1,2,3,4,5,6,7,8,9,10]
 95 | [1..10]
 96 | ```
 97 | Both the above gives the same meaning as you can also use range to define lists
 98 | 
 99 | Some of the common list operations
100 | 
101 | |List Operations| Description|
102 | |----|----|
103 | |list1+list2| to append two lists list1+list2|
104 | | list1!!n | to return element n from list1|
105 | | head/last list1| to retrieve the first/last element of the list1|
106 | | sum list1| to get the sum of all list elements present in list1|
107 | | prod list1| to get the product of all list elements  present in list1|
108 | | reverse list1 | to reverse the elements present in list1|
109 | 
110 | ## Functions
111 | 
112 | ### How to define and call a Function
113 | 
114 | ```java
115 | functionname :: data type [-> datatype] -> data type -- function definition 
116 | --code
117 | 
118 | functionname(variable) -- calling a function
119 | ```
120 | ### Examples
121 | ```java
122 | multiply :: Integer -> Integer -> Integer   --declaration of a function 
123 | multiply x1 x2 =  x1 * x2                       --definition of a function
124 | 
125 | main = do 
126 |    putStrLn "Multiplication value is:"  
127 |    print(multiply 10 5)    --calling a function
128 | ```


--------------------------------------------------------------------------------
/head.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: head Linux Command
  3 | description: head Linux Command is used to display beginning of a text file/ piped data.
  4 | created: 2019-09-13
  5 | updated: 2019-09-13
  6 | ---
  7 | 
  8 | head Linux Command is used to display beginning of a text file/ piped data.
  9 | 
 10 | 
 11 | ## Syntax
 12 | 
 13 | ```sh
 14 | head [options] file-name
 15 | ```
 16 | 
 17 | ## Examples
 18 | 
 19 | For example consider the following file
 20 | 
 21 | ```sh
 22 | $ cat readme.txt 
 23 | line1
 24 | line2
 25 | line3
 26 | line4
 27 | line5
 28 | line6
 29 | line7
 30 | line8
 31 | line9
 32 | line10
 33 | line11
 34 | line12
 35 | line13
 36 | line14
 37 | line15
 38 | ```
 39 | 
 40 | ```sh
 41 | $ head readme.txt
 42 | line1
 43 | line2
 44 | line3
 45 | line4
 46 | line5
 47 | line6
 48 | line7
 49 | line8
 50 | line9
 51 | line10 
 52 | ```
 53 | 
 54 | ```
 55 | Note: head by default shows first 10 lines
 56 | ```
 57 | 
 58 | ### Showing first 2 lines
 59 | 
 60 | ```sh
 61 | $ head -n 2 readme.txt
 62 | line1
 63 | line2
 64 | ```
 65 | 
 66 | ### Showing first 5 lines
 67 | 
 68 | ```sh
 69 | $ head -n 5 readme.txt
 70 | line1
 71 | line2
 72 | line3
 73 | line4
 74 | line5
 75 | ```
 76 | 
 77 | ### Showing from multiple files
 78 | ```sh
 79 | $ head -n 2 readme.txt readme-2.txt
 80 | ==> readme.txt <==
 81 | line1
 82 | line2
 83 | 
 84 | ==> readme-2.txt <==
 85 | line1
 86 | line2
 87 | ```
 88 | 
 89 | ### Showing from all files that are starting with readme
 90 | ```sh
 91 | $ head -n 2 readme*
 92 | ==> readme-2.txt <==
 93 | line1
 94 | line2
 95 | 
 96 | ==> readme-3.txt <==
 97 | line1
 98 | line2
 99 | 
100 | ==> readme.txt <==
101 | line1
102 | line2
103 | 
104 | ```


--------------------------------------------------------------------------------
/heroku.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Heroku
 3 | description: Heroku is a platform as a service based on a managed container system. Heroku started with Ruby support and now we can deploy apps from Java, Node.js, Scala, Clojure, Python, PHP, and Go
 4 | created: 2019-08-13
 5 | updated: 2019-08-13
 6 | color: #79589F
 7 | ---
 8 | 
 9 | Heroku is a platform as a service based on a managed container system. Heroku started with Ruby support and now we can deploy apps from Java, Node.js, Scala, Clojure, Python, PHP, and Go.
10 | 
11 | ## Available Regions
12 | 1. United States
13 | 2. Europe
14 | 
15 | ## Products
16 | 1. Heroku Platform
17 | 2. Heroku Postgres
18 | 3. Heroku Redis
19 | 4. Heroku Teams
20 | 5. Heroku Enterprise
21 | 6. Heroku Connect
22 | 7. Heroku Elements
23 | 
24 | ## Get started with Heroku
25 | 
26 | Heroku: Cloud Application Platform https://www.heroku.com
27 | Heroku Documentation:- https://devcenter.heroku.com/categories/reference
28 | 
29 | 
30 | 
31 | 


--------------------------------------------------------------------------------
/homebrew.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Homebrew
 3 | description: Homebrew is a simple package management software for macOS & Linux. This Cheatsheat shows how to search, install, upgrade & uninstall softwares using Homebrew
 4 | created: 2019-06-16
 5 | updated: 2019-06-16
 6 | color: #2e2a24
 7 | ---
 8 | 
 9 | ## Installation for MacOS
10 | 
11 | ####   Prerequisities
12 | Install command-line tools if not already installed by running the following command 
13 | ```sh
14 | xcode-select --install
15 | ```
16 | Note: If you have installed Xcode already then your mac already have command-line tools. 
17 | 
18 | #### Install Homebrew
19 | 
20 | 
21 | ```sh
22 | /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
23 | ```
24 | 
25 | 
26 | ## Installing a software
27 | You can install brew available softwares by running the following command 
28 | ```sh
29 | brew install <software_name>
30 | ```
31 | example
32 | ```sh
33 | brew install mongodb
34 | ```
35 | If you want to install a specific version of a sooftware, you can mention the available version name using `@<version>`
36 | 
37 | Example
38 | ```sh
39 | brew install mongodb@3.6
40 | ```
41 | 
42 | ## Uninstalling a softwware
43 | You can uninstall a installed software by running the following command 
44 | ```sh
45 | brew remove <software_name>
46 | ```
47 | example
48 | ```sh
49 | brew remove mongodb
50 | ```
51 | 
52 | ## Searching for a software 
53 | You can search available softwares by running following command
54 | ```sh
55 | brew search <software_name>
56 | ```
57 | Example 
58 | ```sh
59 | $ brew search mongodb
60 | ==> Formulae
61 | mongodb ✔                                mongodb@3.2                              mongodb@3.6
62 | mongodb@3.0                              mongodb@3.4                              percona-server-mongodb
63 | 
64 | ==> Casks
65 | mongodb                                  mongodb-compass-community                mongodbpreferencepane
66 | mongodb-compass                          mongodb-compass-isolated-edition         nosqlbooster-for-mongodb
67 | mongodb-compass-beta                     mongodb-compass-readonly                 orelord-mongodb
68 | ```
69 | 
70 | ## Other useful commands
71 | 
72 | 
73 | |Command|Use| Example|
74 | |---|---|---|
75 | |`brew doctor`| self-diagnose shows if the installatin is correct or not|NA|
76 | |`brew upgrade <software_name>`|To Update a installed sooftware| `brew upgrade mongodb`|
77 | 
78 | ## Uninstalling Homebrew
79 | In case you decided to completely uninstall Homebrew from your Mac, you can run the followiong command to uninstall
80 | 
81 | ```sh
82 | ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/uninstall)"
83 | 
84 | ```
85 | 
86 | 


--------------------------------------------------------------------------------
/http-staus-codes.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Http Status Codes
  3 | description: Http is what protocol ussed by the modern internet, there are multiple codes returned on the basis of what comes an outcome to a http request.
  4 | created: 2022-10-05
  5 | updated: 2020-10-05
  6 | ---
  7 | 
  8 | ## Http Status Codes
  9 | 
 10 | Http is what protocol ussed by the modern internet, there are multiple codes returned on the basis of what comes an outcome to a http request
 11 | 
 12 | > Do note that the code not mentioned in the cheatsheet are not officially assigned and upto the server manager to assign for their convinence
 13 | 
 14 | ### Http classes
 15 | 
 16 | | Class | Info                   |
 17 | | ----- | ---------------------- |
 18 | | 1xx   | informational response |
 19 | | 2xx   | successful             |
 20 | | 3xx   | redirection            |
 21 | | 4xx   | client error           |
 22 | | 5xx   | server error           |
 23 | 
 24 | #### **1xx informational response**
 25 | 
 26 | | Status Code | Meaning             |
 27 | | ----------- | ------------------- |
 28 | | 100         | Continue            |
 29 | | 101         | Switching Protocols |
 30 | 
 31 | #### **Success Responses**
 32 | 
 33 | | Status Code | Meaning                     |
 34 | | ----------- | --------------------------- |
 35 | | 200         | OK
 36 | | 201         | Created                     |
 37 | | 202         | Accepted                    |
 38 | | 203         | Non-Authoritive Information |
 39 | | 204         | No Content                  |
 40 | | 205         | Reset Content               |
 41 | | 206         | Partial Content             |
 42 | | 226         | IM Used                     |
 43 | 
 44 | #### **Redirection Responses**
 45 | 
 46 | | Status Code | Meaning            |
 47 | | ----------- | ------------------ |
 48 | | 300         | Multiple Choices   |
 49 | | 301         | Moved Permanently  |
 50 | | 302         | Found              |
 51 | | 303         | See Other          |
 52 | | 304         | Not Modified       |
 53 | | 305         | Use Proxy          |
 54 | | 306         | Switch Proxy       |
 55 | | 307         | Temporary Redirect |
 56 | | 308         | Permanent Redirect |
 57 | 
 58 | #### **Client Error Responses**
 59 | 
 60 | | Status Code | Meaning                         |
 61 | | ----------- | ------------------------------- |
 62 | | 400         | Bad Request                     |
 63 | | 401         | Unauthorized                    |
 64 | | 402         | Payment Required                |
 65 | | 403         | Forbidden                       |
 66 | | 404         | Not Found                       |
 67 | | 405         | Method Not Allowed              |
 68 | | 406         | Not Acceptable                  |
 69 | | 407         | Proxy Authentication Required   |
 70 | | 408         | Request Timeout                 |
 71 | | 409         | Conflict                        |
 72 | | 410         | Gone                            |
 73 | | 411         | Length Required                 |
 74 | | 412         | Precondition Failed             |
 75 | | 413         | Payload Too Large               |
 76 | | 414         | URI Too Long                    |
 77 | | 415         | Unsupported Media Type          |
 78 | | 416         | Range Not Satisfiable           |
 79 | | 417         | Expectation Failed              |
 80 | | 418         | I’m a teapot                    |
 81 | | 421         | Misdirected Request             |
 82 | | 426         | Upgrade Required                |
 83 | | 428         | Precondition Required           |
 84 | | 429         | Too Many Requests               |
 85 | | 431         | Request Header Fields Too Large |
 86 | | 451         | Unavailable For Legal Reasons   |
 87 | 
 88 | #### **Server Error Responses**
 89 | 
 90 | | Status Code | Meaning                         |
 91 | | ----------- | ------------------------------- |
 92 | | 500         | Internal Server Error           |
 93 | | 501         | Not Implemented                 |
 94 | | 502         | Bad Gateway                     |
 95 | | 503         | Service Unavailable             |
 96 | | 504         | Gateway Timeout                 |
 97 | | 505         | HTTP Version Not Supported      |
 98 | | 506         | Variant Also Negotiates         |
 99 | | 510         | Not Extended                    |
100 | | 511         | Network Authentication Required |
101 | 


--------------------------------------------------------------------------------
/iphone-screen-resolutions.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: iPhone screen resolutions
 3 | description: iPhone screen resolutions for developers
 4 | created: 2019-08-16
 5 | updated: 2019-08-16
 6 | color: #636e72
 7 | ---
 8 | 
 9 | | Device Model | Native Resolution (Pixels) | Points | Screen Size (Inches) |
10 | |:------------:|:--------------------------:|:------:|:--------------------:|
11 | |iPhone 14 Pro Max|1290 x 2796|430 × 932|6.7"|
12 | |iPhone 14 Pro|1179 x 2556|393 × 852|6.1"|
13 | |iPhone 14 Plus|1284 x 2778|428 × 926|6.7"|
14 | |iPhone 14|1170 x 2532|390 × 844|6.1"|
15 | |iPhone SE 3rd gen|750 x 1334|375 x 667|4.7"|
16 | |iPhone 13 Pro Max|1284 x 2778|428 x 926|6.68"|
17 | |iPhone 13, 13 Pro|1170 x 2532|390 x 844|6.06"|
18 | |iPhone 13 mini|1080 x 2340|375 x 812|5.42"|
19 | |iPhone 12 Pro Max|1284 x 2778|428 x 926|6.68"|
20 | |iPhone 12, 12 Pro|1170 x 2532|390 x 844|6.06"|
21 | |iPhone 12 mini|1080 x 2340|375 x 812|5.42"|
22 | |iPhone SE 2nd gen|750 x 1334|375 x 667|4.7"|
23 | |iPhone 11 Pro Max|1242 x 2688|414 x 896|6.46"|
24 | |iPhone 11 Pro|1125 x 2436|375 x 812|5.85"|
25 | |iPhone 11|828 x 1792|414 x 896|6.1"|
26 | |iPhone Xr|828 x 1792|414 × 896|6.06"|
27 | |iPhone Xs Max|1242 x 2688|414 x 896|6.46"|
28 | |iPhone X, Xs|1125 x 2436|375 × 812|5.85"|
29 | |iPhone 8+|1080 × 1920|414 × 736|5.5"|
30 | |iPhone 8|750 x 1334|375 × 667|4.7"|
31 | |iPhone 7+|1242 x 2208|476 x 847|5.5"|
32 | |iPhone 7|750 x 1334|375 × 667|4.7"|
33 | |iPhone SE 1st gen|640 × 1136|320 × 568|4"|
34 | |iPhone 6+, 6s+|1242 x 2208|476 x 847|5.5"|
35 | |iPhone 6, 6s|750 x 1334|375 × 667|4.7"|
36 | |iPhone 5, 5s, 5C|640 × 1136|320 × 568|4"|
37 | |iPhone 4, 4S|640 × 960|320 × 480|3.5"|
38 | |iPhone 3G, 3GS|320 × 480|320 × 480|3.5"|
39 | |iPhone 1st gen|320 × 480|320 × 480|3.5"|
40 | 


--------------------------------------------------------------------------------
/java-primitive-data-types.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Java Primitive Data Types
 3 | description: Primitive Data Types in Java Language
 4 | created: 2018-01-21
 5 | updated: 2018-01-21
 6 | color: #027395
 7 | ---
 8 | 
 9 | #### Integer
10 | 
11 | | Data Type | Size (bits)| Range |
12 | |--------|--------|--------|
13 | |byte|8|-128 to 127|
14 | |char|16|0 to 2^16-1|
15 | |short|16|-2^15 to 2^15-1|
16 | |int|32|-2^31to 2^31-1|
17 | |long|64|-2^63 to 2^63-1|
18 | 
19 | #### Floating Point
20 | 
21 | | Data Type | Size (bits)| Range |
22 | |--------|--------|--------|
23 | |float|32| 3.40282347*10^38 to 1.40239846*10^(-45)          |
24 | |double|64| 1.7976931348*10^308 to 4.946564584*10^(-324)    |
25 | 
26 | #### Other
27 | * boolean
28 | 


--------------------------------------------------------------------------------
/java-versions.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Java Versions
 3 | description: Java Versions with release years and features added
 4 | created: 2019-08-19
 5 | updated: 2022-10-01
 6 | color: #f4de50
 7 | ---
 8 | 
 9 | | Version | Year | Features added |
10 | |--------|--------|--------|
11 | |JDK Beta|1995| |
12 | |JDK 1.0|January 1996| |
13 | |JDK 1.1|February 1997	|AWT, JDBC, RMI, JIT|
14 | |J2SE 1.2|December 1998|Swing, Collections|
15 | |J2SE 1.3|May 2000|Hotspot JVM, JNDI, JPDA|
16 | |J2SE 1.4|February 2002|Regular Expressions, Non blocking I/O, JAXP, Exception Handeling|
17 | |J2SE 5.0|September 2004|Generics, Enumaration, static imports, Varargs, for each, Auto boxing|
18 | |Java SE 6|December 2006|JAX-WS, JDBC 4, Supports Annotations, JAXB 2.0, compiler level performance|
19 | |Java SE 7|July 2011|Strings in switch, Concurrency utilities, java.nio packages|
20 | |Java SE 8|March 2014|lambda expressions, functional interfaces, new Date api, Streams, JavaFX|
21 | |Java SE 9|September 2017|Modularization, jshell, Reactive Streams|
22 | |Java SE 10|March 2018|Local-variable type inference, Java-based JIT compiler, Parallel full GC for G1, Thread-local handshakes, Heap allocation on alternative memory devices|
23 | |Java SE 11|September 2018|Dynamic class-file constants, Epsilon: a no-op garbage collector, Local-variable syntax for lambda parameters, HTTP client|
24 | |Java SE 12|March 2019|Switch Expressions, Default CDS archives, Microbenchmark, |
25 | |Java SE 13|September 2019|FileSystems.newFileSystem() Method, DOM and SAX Factories with Namespace Support, Text Blocks, Switch Expressions Enhancements|
26 | |Java SE 14|March 20202|Switch Expressions, Helpful NullPointerExceptions, JFR Event Streaming, Remove the Pack200 Tools and API |
27 | |Java SE 15|September 2020|EdDSA Algorithm, Hidden classes, Removed Nashorn JS engine|
28 | |Java SE 16|March 2021|Records, Vector API, Alpine Linux Port|
29 | |Java SE 17 (LTS)|September 2021|Deprecate the Security Manager for Removal, Sealed Classes, Strongly Encapsulate JDK Internals|
30 | |Java SE 18|March 2022|UTF-8 By Default, Simple Web Server, Deprecate Finalization for Removal|
31 | |Java SE 19|September 2022|New System Properties for System.out and System, New Methods to Create Preallocated HashMaps|
32 | 


--------------------------------------------------------------------------------
/javascript-fetch.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: JavaScript Fetch API
 3 | description: The Fetch API provides a JavaScript interface for accessing and manipulating parts of the HTTP pipeline, such as requests and responses.
 4 | created: 2018-11-05
 5 | updated: 2018-11-05
 6 | color: #f4de50
 7 | ---
 8 | 
 9 | ## get
10 | 
11 | ```javascript
12 | fetch('https://jsonplaceholder.typicode.com/todos')
13 |       .then(res => res.json())
14 |       .then(json => console.log(json))
15 | ```
16 | 
17 | ## post formdata
18 | 
19 | ```javascript
20 | const formData = new FormData();
21 | formData.append('name', 'foo');
22 | 
23 | fetch(`[url]`, { method: 'POST', body: formData})
24 |         .then(res => res.text())
25 |         .then(text => console.log(text))
26 | ```
27 | 
28 | ## post application/json
29 | 
30 | ```javascript
31 | await fetch(`[url]`, {
32 |     method: 'POST',
33 |     headers: {
34 |         'Accept': 'application/json',
35 |         'Content-Type': 'application/json'
36 |       },
37 |       body: JSON.stringify([dataObject])
38 |     }).then(res => res.json())
39 |       .then(json => console.log(json))
40 | ```
41 | 


--------------------------------------------------------------------------------
/javascript-versions.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: JavaScript Versions
 3 | description: JavaScript/ ECMAScript Versions with release years and features added
 4 | created: 2018-10-21
 5 | updated: 2022-10-06
 6 | color: #f4de50
 7 | ---
 8 | 
 9 | | Version | Year | Version Name (s) | Features added |
10 | |--------|--------|--------|--------|
11 | |1|1997|ECMAScript 1| |
12 | |2|1998|ECMAScript 2| |
13 | |3|1999|ECMAScript 3|Regular Expressions, try-catch blocks|
14 | |4|Not Released|ECMAScript 4| |
15 | |5|2009|ECMAScript 5|strict mode, JSON support|
16 | |5.1|2011|ECMAScript 5.1| |
17 | |6|2015|ECMAScript 2015 (ES 6)|let and const, Modules, Promises, Classes & Inheritance, Template Literals, Object destructing, Generators, Map and Set, default parameter values|
18 | |7|2016|ECMAScript 2016|Array.includes(), `**`|
19 | |8|2017|ECMAScript 2017|Async Functions, Object.entries, String padding, shared memory|
20 | |9|2018|ECMAScript 2018|Spread operator, asynchronous iteration, Promise.finally(), Regexp additions|
21 | |10|2019|ECMAScript 2019|Optional catch binding, Object.fromEntries, Array.flat(), String.fromStart(), String.trimEnd()|
22 | |11|2020|ECMAScript 2020|Nullish coalescing operator (??)|
23 | 


--------------------------------------------------------------------------------
/jest.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: jest (Javascript Library)
 3 | description: Jest is a javascript library which privides utility functions to write unit tests
 4 | created: 2019-11-07
 5 | updated: 2019-11-07
 6 | ---
 7 | 
 8 | Jest is a javascript library which privides utility functions to write unit tests.
 9 | Jest also consists of testrunner which is used to generate a test report by running program in command line.
10 | 
11 | ## Installation
12 | 
13 | 1. Using NPM
14 | 
15 | ```sh
16 | npm install jest --save--dev
17 | ```
18 |  Note: Install jest as dev dependency
19 | 
20 | ## Popular jest matcher functions
21 | 
22 | ## Equality
23 | 
24 | |Matcher_function|Description|
25 | |---|---|
26 | |`expect(...).toBe();`|Check for the equality of data|
27 | |`expect(...).toEqual()`|Check for the equality of data|
28 | 
29 | ## Truthiness
30 | |Matcher_function|Description|
31 | |---|---|
32 | |`expect(...).toBeDefined();`|To check whether a function returning data or not|
33 | |`expect(...).toBeNull();`|Check whether something is null|
34 | |`expect(...).toBeTruthy();`|Check whether it returns true|
35 | |`expect(...).toBeFalsy();`|Check whether it returns false|
36 | 
37 | ## Numbers 
38 | |Matcher_function|Description|
39 | |---|---|
40 | |`expect(...).toBeGreaterThan();`|Checks whether number is greater or not |
41 | |`expect(...).toBeGreaterThanOrEqual();`|Checks whether number is greater or equal|
42 | |`expect(...).toBeLessThan()`| Checks whether number is smaller or not |
43 | |`expect(...).toBeLessThanOrEqual()`|Checks whether number is smaller or equal|
44 | 
45 | 
46 | ## Strings
47 | |Matcher_function|Description|
48 | |---|---|
49 | |`expect(...).toMatch(/regularExp/);`||
50 | 
51 | 
52 | 
53 | ## Arrays
54 | |Matcher_function|Description|
55 | |---|---|
56 | |`expect(...).toContain();`|Checks whether element is present in array or not|
57 | 
58 | 
59 | ## Objects
60 | |Matcher_function|Description|
61 | |---|---|
62 | |`expect(...).toBe();`|Check for the equality of object|
63 | |`expect(...).toEqual()`|Check for the equality of object|
64 | |`expect(...).toMatchObject()`|Check for the equality of object|
65 | 
66 | ## Exceptions
67 | |Matcher_function|Description|
68 | |---|---|
69 | |`expect(() => { someCode }).toThrow();`|Check for the equality of exceptions|
70 | 


--------------------------------------------------------------------------------
/jshell.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: JShell 
 3 | description: JShell cheatsheet contains useful code syntax with examples which is handy while coding.
 4 | created: 2020-04-26
 5 | updated: 2020-04-26
 6 | ---
 7 | Jshell is Java’s first official REPL (READ-EVAL-PRINT-LOOP) tool which provides interactive use of Java Programming Language elements.
 8 | 
 9 | ## Variables
10 | When you evaluate any valid java expression, the result will be stored in the system defined variables.
11 | 
12 | ### User-defined variables syntax:
13 | ```java
14 | datatype variable name = value;
15 | ```
16 | ## Commands
17 | 
18 | * To launch Jshell tool
19 |     ```sh
20 |     jshell
21 |     ```
22 | * To exit Jshell
23 |     ```sh
24 |     exit
25 |     ```
26 | * To list all the declared variables.
27 |     ```sh
28 |     /vars
29 |     /vars <variableName>
30 |     /vars <variableSnippetId>
31 |     /vars -start
32 |     /vars -all
33 |     ```
34 |     ### Example:
35 |     ```sh
36 |     jshell> /vars
37 |     |       String name = "OneCompiler"
38 |     |       int id = 1
39 |     ```
40 | 
41 | * To list all the declared Methods
42 |     ```sh
43 |     /methods
44 |     /methods <methodName>
45 |     /methods <methodSnippetId>
46 |     /methods -start
47 |     /methods -all
48 |     ```
49 | 
50 |     ### Example:
51 |     ```sh
52 |     jshell> /methods
53 |     |    double sum(int,int)
54 |     ```
55 | 
56 | * To displays classes, interfaces, and enums 
57 |     ```sh
58 |     /types
59 |     /types <typeName>
60 |     /types <typeSnippetId>
61 |     /types -start
62 |     /types -all
63 |     ```    
64 | * To see a list all the snippets
65 |     ```sh
66 |     /list
67 |     /list -all
68 |     /list -start
69 |     /list <snippetName>
70 |     /list <snippetId>
71 |     ```
72 | * To save your snippets
73 |     ```sh
74 |     /save
75 |     ```
76 | * To personalize your startup entries
77 |     ```sh
78 |     /set start
79 |     ```
80 | * To get help about the list of the JShell commands.
81 |     ```sh
82 |     /help
83 |     ```
84 | * To edit code of a method
85 |     ```sh
86 |     /edit method-name
87 |     ```
88 | * To load Code from External Java File into REPL:
89 |     ```sh
90 |     /open filename.java
91 |     ```
92 |     You can also provide directory information along wwith filename.java if the file is present in different directory like `/open c:\\Documents\\filename.java`
93 | 
94 | * To Drop a Snippet
95 |     ```sh
96 |     /drop <snippetName>
97 |     /drop <snippetId>
98 |     ```


--------------------------------------------------------------------------------
/jsonata.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Jsonata (Javascript Library)
 3 | description: Jsonata is a Javascript library which is used to querying and transforming JSON data
 4 | created: 2019-10-10
 5 | updated: 2019-10-14
 6 | ---
 7 | 
 8 | Jsonata is a Javascript library which is used to querying and transforming JSON data
 9 | 
10 | ## Installation
11 | 
12 | ``` sh
13 | 1. Using NPM
14 | 
15 | $ npm install jsonata
16 | ```
17 | 
18 | ## Sample Usage
19 | ``` javascript
20 | const jsonata = require('jsonata');
21 | 
22 | var empdetails = {
23 |     "employeeDetails": {
24 |       "companyName": "xyz", 
25 |     "details":[{
26 |       "name": "Sasi",
27 |       "age": 25,
28 |       "role": "Software Engineer",
29 |       "salary": 500000,
30 |       "joiningDate": "23/10/2019"
31 |     },
32 |     {
33 |       "name": "Varun",
34 |       "age": 31,
35 |       "role": "Android Developer",
36 |       "salary": 600000,
37 |       "joiningDate": "30/05/2016"
38 |     },
39 |     {
40 |       "name": "Krishna",
41 |       "age": 29,
42 |       "role": "Devops",
43 |       "salary": 400000,
44 |       "joiningDate": "12/09/2018"
45 |     },
46 |     {
47 |       "name": "Sravani",
48 |       "age": 23,
49 |       "role": "Devops",
50 |       "salary": 300000,
51 |       "joiningDate": "23/10/2019"
52 |     }
53 |     ]
54 |   }
55 | 
56 | var employeeNames = jsonata("employeeDetails.details.name");  
57 | console.log(employees.evaluate(empdetails));  //=>  [Sasi, Varun, Krishna, Sravani]
58 | 
59 | var numberOfEmployees = jsonata("employeeDetails.$count(details)");  
60 | console.log(numberOfEmployees.evaluate(empdetails));   //=> 4
61 | 
62 | var totalSalaryPerMonth = jsonata("employeeDetails.($sum((details.salary)))/12");
63 | console.log(totalSalaryPerMonth.evaluate(empdetails));  //=> 150000
64 | 
65 | 
66 | var roles = jsonata("employeeDetails.details.role");
67 | console.log(roles.evaluate(empdetails));   //=> [Software Engineer, Android Developer, Devops, Devops]
68 | 
69 | var employees = jsonata("employeeDetails.details{name:{"role": role, "Salary": salary}}")
70 | console.log(empoyees.evaluate(empDetails));  /* => {
71 |   "Sasi": {
72 |     "role": "Software Engineer",
73 |     "Salary": 500000
74 |   },
75 |   "Varun": {
76 |     "role": "Android Developer",
77 |     "Salary": 600000
78 |   },
79 |   "Krishna": {
80 |     "role": "Devops",
81 |     "Salary": 400000
82 |   },
83 |   "Sravani": {
84 |     "role": "Devops",
85 |     "Salary": 300000
86 |   }
87 | } */
88 | 
89 | 
90 | ```
91 | We can write these kind of expressions using jsonata and also query the data.
92 | 


--------------------------------------------------------------------------------
/kill.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: kill Linux Command
  3 | description: kill Linux Command is used to send signals to running processes.
  4 | created: 2019-09-13
  5 | updated: 2019-09-13
  6 | ---
  7 | 
  8 | kill Linux Command is used to send signals to running processes.
  9 | 
 10 | 
 11 | ## Syntax
 12 | 
 13 | ```sh
 14 | kill [SIGNAL] PID
 15 | ```
 16 | 
 17 | ## Examples
 18 | 
 19 | ```sh
 20 | kill -9 3829 #=> kills process with id 3829
 21 | ```
 22 | 
 23 | ## Options
 24 | 
 25 | `kill -l` command display all available options with kill
 26 | 
 27 | ### Note: Following are from Ubuntu 16.04
 28 | 
 29 | |Signal|Description|
 30 | |---|---|
 31 | |1| SIGHUP|
 32 | |2| SIGINT|
 33 | |3| SIGQUIT|
 34 | |4| SIGILL|
 35 | |5| SIGTRAP|
 36 | | 6| SIGABRT|
 37 | | 7| SIGBUS|
 38 | | 8| SIGFPE|
 39 | | 9| SIGKILL|
 40 | |10| SIGUSR1|
 41 | |11| SIGSEGV|
 42 | |12| SIGUSR2|
 43 | |13| SIGPIPE|
 44 | |14| SIGALRM|
 45 | |15| SIGTERM|
 46 | |16| SIGSTKFLT|
 47 | |17| SIGCHLD|
 48 | |18| SIGCONT|
 49 | |19| SIGSTOP|
 50 | |20| SIGTSTP|
 51 | |21| SIGTTIN|
 52 | |22| SIGTTOU|
 53 | |23| SIGURG|
 54 | |24| SIGXCPU|
 55 | |25| SIGXFSZ|
 56 | |26| SIGVTALRM|
 57 | |27| SIGPROF|
 58 | |28| SIGWINCH|
 59 | |29| SIGIO|
 60 | |30| SIGPWR|
 61 | |31| SIGSYS|
 62 | |34| SIGRTMIN|
 63 | |35| SIGRTMIN+1|
 64 | |36| SIGRTMIN+2|
 65 | |37| SIGRTMIN+3|
 66 | |38| SIGRTMIN+4|
 67 | |39| SIGRTMIN+5|
 68 | |40| SIGRTMIN+6|
 69 | |41| SIGRTMIN+7|
 70 | |42| SIGRTMIN+8|
 71 | |43| SIGRTMIN+9|
 72 | |44| SIGRTMIN+10|
 73 | |45| SIGRTMIN+11|
 74 | |46| SIGRTMIN+12|
 75 | |47| SIGRTMIN+13|
 76 | |48| SIGRTMIN+14|
 77 | |49| SIGRTMIN+15|
 78 | |50| SIGRTMAX-14|
 79 | |51| SIGRTMAX-13|
 80 | |52| SIGRTMAX-12|
 81 | |53| SIGRTMAX-11|
 82 | |54| SIGRTMAX-10|
 83 | |55| SIGRTMAX-9|
 84 | |56| SIGRTMAX-8|
 85 | |57| SIGRTMAX-7|
 86 | |58| SIGRTMAX-6|
 87 | |59| SIGRTMAX-5|
 88 | |60| SIGRTMAX-4|
 89 | |61| SIGRTMAX-3|
 90 | |62| SIGRTMAX-2|
 91 | |63| SIGRTMAX-1|
 92 | |64| SIGRTMAX|
 93 | 
 94 | ### Note: Following are from MacOS
 95 | 
 96 | |Signal|Description|
 97 | |---|---|
 98 | | 1| SIGHUP|
 99 | | 2| SIGINT|
100 | | 3| SIGQUIT|
101 | | 4| SIGILL|
102 | | 5| SIGTRAP|
103 | | 6| SIGABRT|
104 | | 7| SIGEMT|
105 | | 8| SIGFPE|
106 | | 9| SIGKILL|
107 | |10| SIGBUS|
108 | |11| SIGSEGV|
109 | |12| SIGSYS|
110 | |13| SIGPIPE|
111 | |14| SIGALRM|
112 | |15| SIGTERM|
113 | |16| SIGURG|
114 | |17| SIGSTOP|
115 | |18| SIGTSTP|
116 | |19| SIGCONT|
117 | |20| SIGCHLD|
118 | |21| SIGTTIN|
119 | |22| SIGTTOU|
120 | |23| SIGIO|
121 | |24| SIGXCPU|
122 | |25| SIGXFSZ|
123 | |26| SIGVTALRM|
124 | |27| SIGPROF|
125 | |28| SIGWINCH|
126 | |29| SIGINFO|
127 | |30| SIGUSR1|
128 | |31| SIGUSR2|


--------------------------------------------------------------------------------
/kubernetes.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Kubernetes
 3 | description: Functionalities of Kubernetes
 4 | created: 2022-10-03
 5 | updated: 2022-10-03
 6 | ---
 7 | 
 8 | Kubernetes also known as K8s is an open source system for automating deployment,scaling and management of containerized applications. K8s makes it easier to manage applications and is a very essectial concept that every Software Developer needs to know.
 9 | 
10 | ## Common Kubectl Commands
11 | 
12 | ```sh
13 | kubectl cluster-info 
14 | ```
15 | Display endpoint information about the master and services in the cluster.
16 | 
17 | ```sh
18 | kubectl version 
19 | ```
20 | Displays the Kubernetes version running on the client and server systems
21 | 
22 | ```sh
23 | kubectl api-resources 
24 | ```
25 | List the API resources that are available
26 | 
27 | ```sh
28 | kubectl config current-context 
29 | ```
30 | Displays the current context available on the data storage
31 | 
32 | ```sh
33 | kubectl config view 
34 | ```
35 | Used to get the configuration of the cluster
36 | 
37 | ## Creating,Updating and Deleting a Resource
38 | 
39 | ```sh
40 | kubectl create namespace [namespace-name] 
41 | ```
42 | To create a resource such as a service, deployment, job, or namespace, we use the kubectl create command
43 | 
44 | ```sh
45 | kubectl apply -f [service-name].yaml 
46 | ```
47 | To apply or update a resource we use the kubectl apply command
48 | 
49 | ```sh
50 | kubectl delete -f pod.yaml
51 | ```
52 | To remove resources from a file, we use the kubectl delete command
53 | 
54 | 
55 | 
56 | 
57 | 
58 | 
59 | 
60 | 
61 | 
62 | 
63 | 
64 | 


--------------------------------------------------------------------------------
/link.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: link Linux Command
 3 | description: link Linux Command is used to create a hard link from an existing directly to a new file/directory
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | link Linux Command is used to create a hard link from an existing directly to a new file/directory
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | link FILE1 FILE2
15 | ```
16 | 
17 | ## Examples
18 | 
19 | ```sh
20 | link source.txt target.txt
21 | ```


--------------------------------------------------------------------------------
/linux.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Unix/Linux commands
 3 | description: Git is a version-control system for tracking changes in computer files and coordinating work on those files among multiple people
 4 | created: 2018-07-18
 5 | updated: 2018-07-18
 6 | ---
 7 | 
 8 | ## Files
 9 | ```sh
10 | ls               # list all files
11 | ls -al           # lists hidden files
12 | cd <path>        # change directory to path
13 | cd               # change to home
14 | pwd              # shows current directory
15 | mkdir <dirName>  # create a new directory with given name
16 | cat <fileName>   # displays the file content
17 | cat > <fileName> # creates a new file
18 | rm <fileName>    # removes file with given name
19 | du -sh *         # list directories with their total sizes 
20 | df -h            # to see free disk space
21 | touch <fileName> # creates a file with given name
22 | 
23 | ```
24 | 
25 | ## Files Permission
26 | ```sh
27 | ls -l                              	# to show file type and access permission
28 | r                                  	# read permission (4)
29 | w                                  	# write permission (2)
30 | x                                  	# execute permission (1)
31 | chown <user>                       	# for changing the ownership of a file/directory
32 | chown <user>: <group> <fileName>   	# change the user as well as group for a file or directory
33 | chmod <mode> <filename>				      # change the permissions of a file/directory
34 | 
35 | ```
36 | 
37 | ## tar/zip
38 | - Use the tar command to compress and expand files from the command line. The syntax is shown below:
39 | 
40 | ### Syntax
41 | - tar [options] [archive-file] [file or directory to be archived] 
42 | 
43 | ```sh
44 | tar -zcvf foo.txt.tar.gz foo.txt	# Create a zipped archive-file
45 | tar -tvf foo.txt.tar.gz				# List archive files
46 | tar -xvf foo.txt.tar.gz				# Extracting archive-file
47 | 
48 | Options:
49 | -c 	# Creates Archive 
50 | -x 	# Extract the archive 
51 | -f 	# creates archive with given filename 
52 | -t 	# displays or lists files in archived file 
53 | -u 	# archives and adds to an existing archive file 
54 | -v 	# Displays Verbose Information 
55 | -A 	# Concatenates the archive files 
56 | -z 	# zip, tells tar command that creates tar file using gzip 
57 | -j 	# filter archive tar file using tbzip 
58 | -W 	# Verify a archive file 
59 | -r 	# update or add file or directory in already existed .tar file
60 | ```
61 | 
62 | ### Process Management
63 | ```sh
64 | ps                # Show snapshot of processes
65 | top               # Show real time processes
66 | kill <pid>        # Kill process with id pid
67 | pkill <name>      # Kill process with name name
68 | killall <name>    # Kill all processes with names beginning name
69 | ```
70 | 
71 | ### Bash Shortcuts
72 | ```sh
73 | CTRL-c          # Stop current command
74 | CTRL-z          # Sleep program
75 | CTRL-a          # Go to start of line
76 | CTRL-e          # Go to end of line
77 | CTRL-u          # Cut from start of line
78 | CTRL-k          # Cut to end of line
79 | CTRL-r          # Search history
80 | !!              # Repeat last command
81 | !abc            # Run last command starting with abc
82 | !abc:p          # Print last command starting with abc
83 | !$              # Last argument of previous command
84 | !*              # All arguments of previous command
85 | ```
86 | 


--------------------------------------------------------------------------------
/lodash.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Lodash (Javascript Library)
  3 | description: Lodash is a Javascript library that provides utility methods for convenience, which are not by default provided with the vanilla javascript. Lodash Library is very light weight (Just 4KB gzipped) and this is the top #1 library by downloads in NPM registry
  4 | created: 2019-06-21
  5 | updated: 2019-06-21
  6 | ---
  7 | 
  8 | Lodash is a Javascript library that provides utility methods for convenience, which are not by default provided with the vanilla javascript. Lodash Library is very light weight (Just 4KB gzipped) and this is the top #1 library by downloads in NPM registry
  9 | 
 10 | ## Usage
 11 | 1. In Browser
 12 | Using a CDN
 13 | ```html
 14 | <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
 15 | ```
 16 | If you download lodash.js file
 17 | ```html
 18 | <script src="lodash.js"></script>
 19 | ```
 20 | 
 21 | 2. Using NPM
 22 | 
 23 | ```sh
 24 | npm i lodash
 25 | ```
 26 | 
 27 | ## Arrays
 28 | 
 29 | #### 1. chunk
 30 | Splits the given array into chunks with the chunk size provided
 31 |  ```javascriopt
 32 | _.chunk(['a', 'b', 'c', 'd', 'e'], 2); // => [['a', 'b'], ['c', 'd'], ['e]]
 33 |  ```
 34 | 
 35 | #### 2. compact
 36 | Removes `false, null, 0, "", undefined, NaN` from a given array
 37 | 
 38 | #### 3. concat
 39 | creates and returns a new array by concatinating fiven array elements/ raw elements
 40 | ```javascript
 41 | _.concat([1, 2], 3, [4]); // => [1, 2, 3, 4]
 42 | ```
 43 | Note: This only concatenate at 1 level of arrays, if you want to concatenate to multi level deep apply flatten too.
 44 | 
 45 | #### 4. drop
 46 | dropns given number of elements from an array from array start
 47 | ```javascript
 48 | _.drop([1, 2, 3, 4], 2); // => [3, 4]
 49 | ```
 50 | #### 5. flatten
 51 | flatten given array to single level deep. 
 52 | ```javascript
 53 | _.flatten([0, 1, [2, 3, 4], [5, [6]], 7]) // => [0, 1, 2, 3, 4, 5, [6], 7]
 54 | ```
 55 | 
 56 | #### 6. flattenDeep
 57 | Recursively flattens given array
 58 | ```javascript
 59 | _.flatten([0, 1, [2, 3, 4], [5, [6]], 7]) // => [0, 1, 2, 3, 4, 5, 6, 7]
 60 | ```
 61 | 
 62 | ## String
 63 | 
 64 | #### 1. Capitalize
 65 | The  _.capitalize() method is used to convert the first character of string to upper case and the remaining to lower case.
 66 | ```javascript
 67 | let str1 = _.capitalize("ONE__COMPILER__CHEATSHEETS");
 68 | console.log(str1);// "One__Compiler__Cheatsheets"
 69 |   
 70 | let str2 = _.capitalize("ONE COMPILER CHEATSHEETS");
 71 | console.log(str2);// "One Compiler Cheatsheets"
 72 | ```
 73 | 
 74 | #### 2. camelCase
 75 | The _.camelCase() method is used to convert a string into a camel case string. The string can be space-separated, dash-separated, or can be separated by underscores.
 76 | ```javascript
 77 | let str1 = _.camelCase("ONE__COMPILER__CHEATSHEETS");
 78 | console.log(str1);// "oneCompilerCheatsheets"
 79 |   
 80 | let str2 = _.camelCase("ONE COMPILER CHEATSHEETS");
 81 | console.log(str2);// "oneCompilerCheatsheets"
 82 | ```
 83 | 
 84 | ## Collection
 85 | 
 86 | #### 1. find
 87 | return the first element that matches predicate
 88 | ```javascript
 89 | _.find([-1, 0, 1, 2, 3], ele => ele > 0) // => 1
 90 | ```
 91 | 
 92 | ## Date
 93 | #### 1. now
 94 | returns the current time in milliseconds
 95 | ```javascript
 96 | _.now() // => 1561104924053
 97 | ```
 98 | 
 99 | ## Function
100 | #### 1. delay
101 | Invokes a function after given wait time (in milliseconds). extra args will be passed to the function when invoked. 
102 | ```javascript
103 | _.delay(func, 1000, arg1, arg2, arg3);
104 | ```
105 | 
106 | ## Lang
107 | #### 1. isArray
108 | return true if given arg is an array
109 | ```javascript
110 | _.isArray([1, 2]); // => true
111 | _.isArray(1); // => false
112 | ```
113 | 
114 | ## Math
115 | #### 1. mean
116 | computes mean value of the values in given array
117 | ```javascript
118 | _.mean([5,10,85, 100]); // => 50
119 | ```
120 | 
121 | ## Number
122 | #### 1. random
123 | provides a random number. lower & upper numbers are optional. If you do not provide any lower or upper, it returns a random between 0 to 1
124 | ```javascript
125 | _.random(100); // => integer between o and 100
126 | _.random(); // => floating-point between 0 to 1
127 | _.random(10, 20); // => integer between 10 to 20
128 | ```
129 | 
130 | ## Object
131 | #### 1. get
132 | reads the value at given path
133 | ```javascript
134 | const user = {
135 |     _id: 1,
136 |     address: {
137 |         streetAddress : "Foo"
138 |     }
139 | }
140 | _.get(user, 'address.streetAddress'); // => Foo
141 | ```
142 | 


--------------------------------------------------------------------------------
/ls.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: ls Linux Command
 3 | description: ls command used to list files and folders in a given directory, If no directory provided it shows from current directoty
 4 | created: 2019-08-21
 5 | updated: 2019-08-21
 6 | ---
 7 | 
 8 | ls command used to list files and folders in a given directory, If no directory provided it shows from current directoty
 9 | 
10 | Lets take following is your directory structure as an example to go through different commands with ls
11 | 
12 | ```
13 | $ tree ./
14 | ./
15 | ├── images
16 | │   ├── cat.png
17 | │   ├── dog.png
18 | │   ├── moon.png
19 | │   └── sun.png
20 | ├── movies
21 | │   ├── action
22 | │   │   ├── bar.mp4
23 | │   │   └── foo.mp4
24 | │   └── comedy
25 | ├── music
26 | │   ├── song1.mp3
27 | │   └── song2.mp3
28 | └── readme.txt
29 | 
30 | 5 directories, 9 files
31 | ```
32 | 
33 | 
34 | ## 1. list files and folders from current directory
35 | 
36 | ```sh
37 | ls
38 | ```
39 | 
40 | #### Output
41 | ```sh
42 | $ ls
43 | images		movies		music		readme.txt
44 | ```
45 | 
46 | ## 2. list detailed informaiton of files and folders from current directory
47 | 
48 | ```sh
49 | ls -l
50 | ```
51 | 
52 | #### Output
53 | ```sh
54 | $ ls -l
55 | total 0
56 | drwxr-xr-x  7 userName  wheel  224 Aug 21 19:31 images
57 | drwxr-xr-x  5 userName  wheel  160 Aug 21 19:23 movies
58 | drwxr-xr-x  4 userName  wheel  128 Aug 21 19:33 music
59 | -rw-r--r--  1 userName  wheel    0 Aug 21 19:34 readme.txt
60 | ```
61 | 
62 | ## 3. Include hidden files in the result
63 | 
64 | ```sh
65 | ls -a
66 | ```
67 | 
68 | ## 4. Show human friendly file sizes 
69 | 
70 | ```sh
71 | ls -h
72 | ```
73 | 
74 | ## 5. List files and folders from a given directory
75 | 
76 | ```sh
77 | ls movies/action/
78 | ```
79 | #### Output
80 | 
81 | ```sh
82 | $ ls movies/action/
83 | bar.mp4	foo.mp4
84 | ```
85 | 
86 | 
87 | ## 6. Combining options
88 | You can run the ls command by combining multiple options like following
89 | 
90 | ```sh
91 | ls -alh
92 | ```


--------------------------------------------------------------------------------
/lua.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Lua
  3 | description: Lua Programming language cheatsheet contains useful code syntax with examples which is handy while coding.
  4 | created: 2020-06-23
  5 | updated: 2020-06-23
  6 | ---
  7 | 
  8 | ## Sample program
  9 | 
 10 | ```lua
 11 | name = io.read("*a")
 12 | print ("Hello ", name)
 13 | ```
 14 | * **io.read** : to read the data from console
 15 | * **print** : to output the data to console. 
 16 | * **--** : comment
 17 | * `--[[` Multi
 18 | 
 19 |     Line
 20 | 
 21 |     comments `--]]`
 22 | 
 23 | 
 24 | ## Variables
 25 | 
 26 | * Lua is a dynamically typed language and hence only the values will have types not the variables.
 27 | 
 28 | ### Examples
 29 | 
 30 | ```c
 31 | -- global variables, variables are by default global
 32 | x = 10
 33 | 
 34 | -- local variables
 35 | 
 36 | local x = 30
 37 | ```
 38 | 
 39 | ## Data types
 40 | 
 41 | |Value Type| Description|
 42 | |-----|-----|
 43 | |number| Represents numbers|
 44 | |string| Represents text|
 45 | |nil|Differentiates values whether it has data or not|
 46 | |boolean|Value can be either true or false|
 47 | |function|Represents a sub-routine|
 48 | |userdata|Represents arbitary C data|
 49 | |thread|Represents independent threads of execution.|
 50 | |table|Can hold any value except nil|
 51 | 
 52 | ## Operators
 53 | 
 54 | | Operator type | Description|
 55 | |----|-----|
 56 | | Arithmetic Operator|+ , - , * , / , %, -|
 57 | | comparision Operator| < , > , <= , >=, ~=, ==|
 58 | | Logical Operator| and , or, not |
 59 | | Misc Operator | .. , # |
 60 | 
 61 | There are no ++, --, ternary operators in lua
 62 | 
 63 | ## String methods
 64 | 
 65 | |Method| Description|
 66 | |----|----|
 67 | | str1 .. str2| String concatenation|
 68 | |string.len(str) | To get the length of a string|
 69 | | string.gsub(str, "t1", "t2")| Used to Replace t1 with t2 in the string str|
 70 | |string.find(str, txt)| Searches for txt in str string and returns it's index|
 71 | |string.upper(str)| to change the str to upper case|
 72 | |string.lower(str)| to change the str to lower case|
 73 | 
 74 | ## Conditional statements
 75 | 
 76 | ### 1. If
 77 | 
 78 | ```c
 79 | if conditional-expression then
 80 | --code
 81 | end
 82 | ```
 83 | 
 84 | ### 2. If-else
 85 | 
 86 | ```lua
 87 | if conditional-expression then
 88 |    --code
 89 | elseif conditional-expression then
 90 |     --code
 91 | else
 92 |     --code
 93 | end
 94 | ```
 95 | There is no switch in Lua
 96 | 
 97 | ## Loops
 98 | 
 99 | ### 1. While
100 | 
101 | ```c
102 | while(condition)
103 | do
104 | --code
105 | end
106 | ```
107 | ### 2. Repeat-Until
108 | 
109 | ```c
110 | repeat
111 |    --code
112 | until( condition )
113 | ```
114 | 
115 | ### 3. For
116 | 
117 | ```c
118 | for init,max/min value, increment
119 | do
120 |    --code
121 | end
122 | ```
123 | 
124 | ##  Functions
125 | 
126 | ```lua
127 | [function_scope] function function_name( argument1, argument2, argument3........, argumentn)
128 | --code
129 | return params with comma seperated
130 | end
131 | ```
132 | ### Example
133 | 
134 | ```lua
135 | function sum(x,y)
136 | 	sum=x+y
137 | 	return sum
138 | end
139 | 
140 | print(sum(10,20)) 
141 | ```


--------------------------------------------------------------------------------
/make.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: make Linux Command
 3 | description: make Linux Command is used to build executable programs, libraries from source code using the definistion from Makefile.
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | make Linux Command is used to build executable programs, libraries from source code using the definistion from `Makefile`.
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | make [ -f makefile ] [ option(s) ] [ target(s) ]
15 | ```
16 | 


--------------------------------------------------------------------------------
/man.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: man Linux Command
 3 | description: man Linux Command is used to display human friendly manual page of a given command.
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | man Linux Command is used to display human friendly manual page of a given command.
 9 | 
10 | ## Syntax
11 | 
12 | ```sh
13 | man [ option(s) ] [ COMMAND ]
14 | ```
15 | 
16 | ## Example
17 | 
18 | ```sh
19 | $ man head
20 | HEAD(1)                   BSD General Commands Manual                  HEAD(1)
21 | 
22 | NAME
23 |      head -- display first lines of a file
24 | 
25 | SYNOPSIS
26 |      head [-n count | -c bytes] [file ...]
27 | 
28 | DESCRIPTION
29 |      This filter displays the first count lines or bytes of each of the speci-
30 |      fied files, or of the standard input if no files are specified.  If count
31 |      is omitted it defaults to 10.
32 | 
33 |      If more than a single file is specified, each file is preceded by a
34 |      header consisting of the string ``==> XXX <=='' where ``XXX'' is the name
35 |      of the file.
36 | 
37 | EXIT STATUS
38 |      The head utility exits 0 on success, and >0 if an error occurs.
39 | 
40 | SEE ALSO
41 |      tail(1)
42 | 
43 | HISTORY
44 |      The head command appeared in PWB UNIX.
45 | 
46 | BSD                              June 6, 1993                              BSD
47 | ```
48 | 
49 | ```sh
50 | Note: To quit than man press `Shift` + `:` then type q
51 | ```
52 | 


--------------------------------------------------------------------------------
/markdown.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Markdown
  3 | description: Markdown is a lightweight markup language which is used to create formatted text using simple text editor.
  4 | created: 2022-10-05
  5 | updated: 2022-10-05
  6 | ---
  7 |  
  8 | # Basic Syntax :
  9 | - ## HEADERS (H1 to H6)
 10 | ```
 11 | #  h1 tag
 12 | ##  h2 tag
 13 | ###  h3 tag
 14 | ####  h4 tag
 15 | #####  h5 tag
 16 | ######  h6 tag
 17 | ```
 18 | ## Output
 19 | #  h1 tag
 20 | ##  h2 tag
 21 | ###  h3 tag
 22 | #### h4 tag
 23 | ##### h5 tag
 24 | ###### h6 tag
 25 | 
 26 | ---
 27 | 
 28 | - ## EMPHASIS 
 29 | ```
 30 | *This is italic*
 31 | _This is also italic_
 32 | **This is bold**
 33 | __This is also bold__
 34 | ```
 35 | ## Output
 36 | *This is italic*
 37 | 
 38 | _This is also italic_
 39 | 
 40 | **This is bold**
 41 | 
 42 | __This is also bold__
 43 | 
 44 | ---
 45 | 
 46 | - ## BLOCKQUOTES
 47 |  ```
 48 | > this is a single block quote.
 49 | >> this is a nested block quote.
 50 | ```
 51 | ## Output
 52 | > this is a single block quote.
 53 | >> this is a nested block quote.
 54 | 
 55 | ---
 56 | 
 57 | - ## LIST
 58 | - ### Ordered List :
 59 |  ```
 60 |   1. First item
 61 |   2. Second item
 62 |   
 63 | ```
 64 | ## Output
 65 |   1. First item
 66 |   2. Second item
 67 | 
 68 |  - ### Unordered List :
 69 |  ```
 70 |   - First item
 71 |    - Second item
 72 |  
 73 |  ```
 74 |  ## Output
 75 |  - First item
 76 |    - Second item
 77 |    
 78 | ---
 79 | 
 80 | - ## Table 
 81 | ```
 82 | | topic       | Description |
 83 | | ----------- | ----------- |
 84 | | text1       | Text 2      |
 85 | | text3       | Text 4      |
 86 | 
 87 | ```
 88 | ## Output
 89 | | topic       | Description |
 90 | | ----------- | ----------- |
 91 | | text1       | Text 2      |
 92 | | text3       | Text 4      |
 93 | 
 94 | ---
 95 | 
 96 | - ## Check Box:
 97 | ```
 98 |  - [ ] task 1
 99 |  - [x] task 2 
100 | ```
101 | ## Output:
102 |  - [ ] task 1
103 |  - [x] task 2 
104 |  
105 | ---
106 | 
107 | - ## HORIZONTAL RULE 
108 | ```
109 | ---
110 | 
111 | ```
112 | ## Output
113 | ---
114 | 
115 | - ## Code
116 | ```
117 |   `This is a code`
118 | ```
119 | ## Output
120 | `This is a code`
121 | ### More Examples :
122 | #### Highlighted C Codes:
123 | ```
124 |   ```c
125 |   Printf("Hello World!");
126 |   ```
127 | 
128 | ## Output
129 | ```c
130 | Printf("Hello World!");
131 | ```
132 | 
133 | #### Highlighted HTML Codes:
134 | ```
135 |   ```html
136 |   <!DOCTYPE html>
137 | <html lang="en">
138 | <head>
139 |     <meta charset="UTF-8">
140 |     <meta name="viewport" content="width=device-width, initial-scale=1.0">
141 |     <meta http-equiv="X-UA-Compatible" content="ie=edge">
142 |     <title>Document</title>
143 | </head>
144 | <body>
145 | 
146 | </body>
147 | </html>
148 |   ```
149 | ## Output
150 |   ```html
151 |   <!DOCTYPE html>
152 | <html lang="en">
153 | <head>
154 |     <meta charset="UTF-8">
155 |     <meta name="viewport" content="width=device-width, initial-scale=1.0">
156 |     <meta http-equiv="X-UA-Compatible" content="ie=edge">
157 |     <title>Document</title>
158 | </head>
159 | <body>
160 | 
161 | </body>
162 | </html>
163 |   ```
164 | ---
165 | 
166 | - ## LINK
167 | ```
168 | Normal link Syntax:
169 | [title](https://www.example.com)
170 | 
171 | Example:
172 | [Github](https://www.github.com)
173 | 
174 | Emails Syntax:
175 | <email id>
176 | 
177 | Example:
178 | <xyz@gmail.com>
179 | ```
180 | ## Output :
181 | [Github](https://www.github.com)
182 | 
183 | <xyz@gmail.com>
184 | 
185 | ---
186 | 
187 | - ## IMAGES
188 | ```
189 | Syntax:
190 | ![image name](image address)
191 | 
192 | Example:
193 | ![unnamed (1)](https://user-images.githubusercontent.com/87390353/194129046-d692bf37-034e-4411-afcd-619585abf2f2.jpg)
194 | ```
195 | ## Output :
196 | ![unnamed (1)](https://user-images.githubusercontent.com/87390353/194129046-d692bf37-034e-4411-afcd-619585abf2f2.jpg)
197 | 
198 | ---
199 | 
200 | # Advanced Syntax :
201 | - ## EMOJI
202 | ```
203 | Syntax:  :short code:
204 | Example : :laughing:
205 | 
206 | ```
207 | ## Output :
208 | :laughing:
209 | 
210 | 
211 | - ## FOOTNOTE
212 | ```
213 | Here's a sentence with a footnote. [^1]
214 | 
215 | [^1]: It is the footnote.
216 | ```
217 | Here's a sentence with a footnote. [^1]
218 | [^1]: It is the footnote.
219 | 
220 | ---
221 | 
222 | - ## STRIKE THROUGH
223 | ```
224 | Syntax:
225 | ~~Sentence~~
226 | 
227 | Example:
228 | ~~This sentence is incorrect~~
229 | ```
230 | ## Output :
231 | 
232 | ~~This sentence is incorrect~~
233 | 
234 | ---
235 | 
236 | # Reference:
237 | [Github Markdown](https://docs.github.com/en/github/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax)
238 | 
239 | ## Keep Learning !
240 | 


--------------------------------------------------------------------------------
/maven.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Maven commands
  3 | description: Maven is a software project management and comprehension tool with project object model (POM), It manages a project's build, reports, documentation from a central piece of information.
  4 | created: 2019-08-07
  5 | updated: 2019-08-07
  6 | ---
  7 | 
  8 | ## Simple clean, compile, install, build commands 
  9 | 
 10 | ```sh
 11 | mvn compile                 #Compiles source code and stores classes to target/classes
 12 | mvn validate                #Validates project 
 13 | mvn test                    #Runs tests
 14 | mvn clean                   #Deletes target directory
 15 | mvn clean package           #Compiled code is packaged to WAR/JAR/deb etc
 16 | mvn clean install           #Install the artifact in local repository(.m2 Repo)
 17 | mvn clean deploy            #Copies the package(WAR/JAR/deb etc) to the remote repository
 18 | mvn verify
 19 | mvn clean verify
 20 | ```
 21 | 
 22 | ## Options 
 23 | 
 24 | ```sh
 25 | mvn clean install -Dmaven.test.skip=true              #Skips compiling and running tests
 26 | mvn clean install -DskipTests=true                    #Compiles but skips running tests
 27 | mvn clean install -Dmaven.test.failure.ignore=true    #Compiles and executes tests but ignores if any tests failed
 28 | mvn verify Dit.test=TestName                          #Executes specified test
 29 | mvn clean install -T 4                                # -T is used to specify number of threads used, default 2 i.e., 2 threads per CPU.
 30 | mvn clean install -X/--debug                          #Enables debug mode
 31 | mvn clean package -U/--update-snapshots               #Force check on dependency updates 
 32 | mvn dependency:purge-local-repository                 #Removes local repository
 33 | ```
 34 | 
 35 | ## Dependency Plugin
 36 | 
 37 | ```sh
 38 | mvn dependency:analyze                                 #Analyzes dependencies of the project
 39 | mvn dependency:tree                                    #Prints dependency tree
 40 | mvn versions:display-dependency-updates                #Displays dependency updates 
 41 | mvn dependency:analyze -DignoreNonCompile=true         #Shows unused dependencies
 42 | ```
 43 | 
 44 | Creates pom.xml:
 45 | ```sh
 46 | mvn archetype:create
 47 | ```
 48 | 
 49 | ## Create java project (JAR):
 50 | 
 51 | ```sh
 52 | mvn archetype:create -DgroupId=org.onecompiler.project -DartifactId=one-compiler -DarchetypeArtifactId=maven-archetype-quickstart
 53 | ```
 54 | 
 55 | ## Create Web project (WAR):
 56 | 
 57 | ```sh
 58 | mvn archetype:create -DgroupId=org.onecompiler.project -DartifactId=one-compiler -DarchetypeArtifactId=maven-archetype-webapp
 59 | ```
 60 | 
 61 | ## Eclipse sources:
 62 | 
 63 | ```sh
 64 | mvn eclipse:eclipse                             #Eclipse creates .project, .settings, .classpath files based on pom.xml    
 65 | mvn eclipse:eclipse -DdownloadSources=true      #Also downloads dependencies
 66 | ```
 67 | 
 68 | Create archetype from project:
 69 | 
 70 | ```sh
 71 | mvn archetype:create-from-project
 72 | ```
 73 | 
 74 | Lists all archetypes:
 75 | 
 76 | ```sh
 77 | mvn archetype:generate
 78 | ```
 79 | 
 80 | ## Useful commands for Automatic deployment with tomcat plugin in your pom.xml
 81 | 
 82 | ```sh
 83 | mvn tomcat:deploy                   #Deploys package
 84 | mvn tomcat:stop                     #Stops tomcat server
 85 | mvn tomcat:start                    #Starts tomcat server
 86 | ```
 87 | 
 88 | Gives description of attributes plugin:
 89 | 
 90 | ```sh
 91 | mvn help:describe -Dplugin=help
 92 | ```
 93 | 
 94 | Describes single goal of plugin:
 95 | 
 96 | ```sh
 97 | mvn help:describe -Dplugin=help -Dmojo=help
 98 | ```
 99 | 
100 | Displays the effective pom.xml for the current build, with the active profiles in it:
101 | 
102 | ```sh
103 | mvn help:effective-pom 
104 | ```
105 | 
106 | Displays active profiles:
107 | 
108 | ```sh
109 | mvn help:active-profiles
110 | ```
111 | 


--------------------------------------------------------------------------------
/mkdir.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: mkdir Linux Command
 3 | description: mkdir Linux Command is used to create new directory. Along with Linux systems mkdir is also available in most of the popular operating systems.
 4 | created: 2019-09-13
 5 | updated: 2023-10-20
 6 | ---
 7 | 
 8 | mkdir Linux Command is used to create new directory. Along with Linux systems mkdir is also available in most of the popular operating systems.
 9 | 
10 | ## Syntax
11 | 
12 | ```sh
13 | mkdir [name-of-directory(s)]
14 | ```
15 | ## Option
16 | 
17 | |Option|Description|
18 | |---|---|
19 | |-m| Set file mode (as in chmod), not a=rwx - umask |
20 | |-p| Make parent directories as needed|
21 | |-v| Verbose - Print a message for each created directory|
22 | 
23 | 
24 | ## Example
25 | 
26 | ```sh
27 | mkdir d1 # creates directory with name d1
28 | ```
29 | 
30 | ```sh
31 | mkdir d2 d3 d4 # creates directories d2, d3 and d4
32 | ```
33 | ```sh
34 | mkdir d1/d2/d3 # creates folder d1, then d2 inside d1 and then finally d3 inside d2
35 | ```


--------------------------------------------------------------------------------
/mv.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: mv Linux Command
 3 | description: mv (move) Linux Command is used to move one or more file/directories from one place to another. This also used to rename files/directories
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | mv (move) Linux Command is used to move one or more file/directories from one place to another. This also used to rename files/directories
 9 | 
10 | ## Syntax
11 | 
12 | ```sh
13 | mv [Option(s)] [source] [destination]
14 | ```
15 | 
16 | ## Options
17 | 
18 | |Option|Description|
19 | |---|---|
20 | |-i| Interactively move|
21 | |-f|Force override destination|
22 | 
23 | ## Example
24 | 
25 | #### Renaming a file 
26 | 
27 | ```sh
28 | mv readme.txt readme-v2.txt
29 | ```
30 | 
31 | #### Moving file to user home folder
32 | 
33 | ```
34 | mv readme.txt ~/
35 | ```
36 | 
37 | #### Moving file to given destination directory
38 | 
39 | ```sh
40 | mv readme.txt /path/to/destination/
41 | ```


--------------------------------------------------------------------------------
/netlify.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Netlify
 3 | description: Netlify is an all-in-one platform for automating modern web projects. Replace your hosting infrastructure, continuous integration, and deployment pipeline with a single workflow. Integrate dynamic functionality like serverless functions, user authentication, and form handling as your projects grow.
 4 | created:  2014-02-7
 5 | updated: 2022-04-13
 6 | color: #79589F
 7 | ---
 8 | 
 9 | Netlify is a remote-first cloud computing company that offers a development platform that includes build, deploy, and serverless backend services for web applications and dynamic websites
10 | 
11 | 
12 | ## Available Regions
13 | 1. All over the world
14 | 
15 | 
16 | ## Netlify CLI Command List
17 | Getting Started
18 | This guide will walk you through installing and creating your first site with the CLI.
19 | 
20 | Installation
21 | Lets get rolling with the Netlify CLI.
22 | 
23 | 1. Install the CLI globally <br>
24 | `npm install netlify-cli -g`
25 | 
26 | 2. Login to your Netlify Account <br>
27 | `netlify login`
28 | 
29 | 3. Initialize a new site <br>
30 | 
31 | Inside of your sites `cwd`, run the following CLI command: <br>
32 | `netlify init`
33 | 
34 | 4. Link an existing site
35 | If your site is already created inside of Netlify, you can run the link command to connect the CLI to your site.
36 | 
37 | `netlify link` <br>
38 | 
39 | In order to know more about Cli commands refer to the netlify <br>
40 | docs: https://cli.netlify.com/commands/
41 | 
42 | Deploy cli commands: https://cli.netlify.com/commands/deploy <br>
43 | Dev: https://cli.netlify.com/commands/dev <br>
44 | 
45 | 
46 | 
47 | ## Get started with Netlify
48 | 
49 | Netlify : https://www.netlify.com/ <br>
50 | Netlify Docs: https://docs.netlify.com/
51 | 


--------------------------------------------------------------------------------
/nodejs.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: NodeJS
  3 | description: Node.js cheatsheet
  4 | created: 2020-01-14
  5 | updated: 2022-10-9
  6 | ---
  7 | 
  8 | ## 1. Create a Nodejs project and install dependent packages
  9 | ### NPM commands
 10 | ```javascript
 11 | // Initialize nodejs project
 12 | npm init
 13 | 
 14 | npm install <package-name> // Installs a package from NPM’s own repository.
 15 | 
 16 | // Install the package present in git
 17 | npm install <git remote url>
 18 | 
 19 | npm update <package-name> // This will update the specified package.
 20 | 
 21 | 
 22 | npm uninstall <package-name> // This uninstalls a package, completely removing everything npm installed on its behalf also removes the package from the dependencies, devDependencies, optionalDependencies, and peerDependencies objects in your package.json.
 23 | 
 24 | // Install a package as dev devDependencies
 25 | npm install -D <package-name>
 26 | ```
 27 | 
 28 | ### Arguments
 29 | 
 30 | `--global` or `-g` : used to install a package globally
 31 | `--production` : This argument will not install modules listed in devDependencies
 32 | 
 33 | 
 34 | ## 2.  How to execute NodeJS file
 35 | 
 36 | ```javascript
 37 | node filename.js
 38 | ```
 39 | 
 40 | ## 3. Modules
 41 | 
 42 | ```javascript
 43 |   const express = require('express'); // to refer the installed package
 44 | 
 45 | const route = require('./route.js'); //to load  the module named route.js
 46 | const router = express.Router();
 47 | 
 48 | module.exports=router;
 49 | ```
 50 | 
 51 | ## 4. How to connect to mongodb
 52 | 
 53 | ```javascript
 54 | const MongoClient = require('mongodb').MongoClient;
 55 | const url = 'mongodb://localhost:27017';
 56 | 
 57 | MongoClient.connect(url, function (err, client) {
 58 |     if (err) {
 59 |         console.log('db connection error');
 60 |     }
 61 |     else
 62 |         if (!err) {
 63 |             console.log("Connected successfully to database");
 64 |             let db = client.db('dbname');
 65 |         }
 66 | });
 67 | ```
 68 | 
 69 | ## 5. Connect with mongodb using mongoose
 70 | 
 71 | ```javascript
 72 | const mongoose = require('mongoose');
 73 | 
 74 | const options = {
 75 |   useNewUrlParser: true,
 76 |   useUnifiedTopology: true,
 77 | };
 78 | 
 79 | const connectDB = async () => {
 80 |   try {
 81 |     const conn = await mongoose.connect(
 82 |       'mongodb://localhost:27017',
 83 |       options,
 84 |     );
 85 |     console.log(`MongoDB Connected: ${conn.connection.host}`);
 86 |   } catch (err) {
 87 |     console.error(err);
 88 |     process.exit(1);
 89 |   }
 90 | };
 91 | 
 92 | module.exports = connectDB;
 93 | ```
 94 | 
 95 | ## 6. Create a basic express server with NodeJs
 96 | 
 97 | ```javascript
 98 | const express = require('express')
 99 | const app = express()
100 | 
101 | // Routes
102 | app.get('/', (req, res) => {
103 |   res.send('Basic express server.')
104 | })
105 | 
106 | 
107 | // Start server
108 | const PORT = process.env.PORT || 8080
109 | app.listen(PORT, console.log(`Server Running at PORT: ${PORT}`))
110 | 
111 | ```
112 | 
113 | ## 7. Console methods [Console API](https://developer.mozilla.org/en-US/docs/Web/API/Console_API)
114 | 
115 | ```javascript
116 | console.log('Your Message'); //prints to stdout
117 | console.error('error message'); //prints to stderr
118 | console.info('Your message'); //same as console.log
119 | console.warn('warning message'); //same as console.error
120 | console.count(); //It is used to count the number of times a specific label has been called.
121 | console.clear(); //It is used to clear the console history.
122 | console.time(); //It is used to get the starting time of an action.
123 | console.timeEnd(); //This function is used to get the end time of specific action.
124 | console.dir(); //It use util.inspect() on object and prints the resulting string to stdout.
125 | ```
126 | 


--------------------------------------------------------------------------------
/nodemon.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Nodemon
 3 | description: Nodemon helps NodeJS applications to restart on file changes
 4 | created: 2019-08-13
 5 | updated: 2019-08-13
 6 | ---
 7 | 
 8 | Nodemon helps NodeJS applications to restart on file changes
 9 | 
10 | ## Installation
11 | 
12 | ```sh
13 | npm install -g nodemon
14 | ```
15 | 
16 | ## Installing as development dependency, specific to project
17 | 
18 | ```sh
19 | npm install --save-dev nodemon
20 | ```
21 | 
22 | ## Starting application with nodemon
23 | If you are doing `node index.js` to start your NodeJS application, then start doing the following to start with Nodemon
24 | ```sh
25 | nodemon index.js
26 | ```
27 | 
28 | ## Monitoring multiple directories
29 | By default Nodemon monitors current working directory, If you want override that behaviour with your specific directories, you can do the following 
30 | ```sh
31 | nodemon --watch server --watch docs --watch client server/index.js
32 | ```
33 | 
34 | In this case Nodemon watches `./server`, `./docs`. `./client` folders
35 | 


--------------------------------------------------------------------------------
/ocaml.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Ocaml 
  3 | description: Ocaml Programming language cheatsheet gives you a quick reference to code syntax with examples makes it handy while coding.
  4 | created: 2020-07-01
  5 | updated: 2020-07-01
  6 | ---
  7 | 
  8 | 
  9 | ## sample program
 10 | 
 11 | ```ocaml
 12 | print_string "Hello world!"
 13 | ```
 14 | 
 15 | * **print_string** : is used to print the given string
 16 | * `(*` Single line comments `*)`
 17 | *  `(*` Multi
 18 |     
 19 |     `*` line
 20 |  
 21 |      `*` comment.
 22 |      
 23 |     ` *)`
 24 | 
 25 | ## Data types
 26 | 
 27 | | Classification | Data-types |
 28 | |----|----|
 29 | | Basic data types| int, float, bool, char, string, unit.|
 30 | | Sophisticated data types| tuples, arrays, lists, sets, hash tables, queues, stacks, data streams.|
 31 | 
 32 | ## Variables
 33 | 
 34 | ```ocaml
 35 | let varible-names = value
 36 | ```
 37 | ### Example
 38 | ```ocaml
 39 | let a = 100;
 40 | ```
 41 | ## Conditional Statements
 42 | 
 43 | ### 1. If
 44 | 
 45 | ```ocaml
 46 | if boolean-condition then (* code if condition is true *)
 47 | ```
 48 | 
 49 | ### 2. If-else
 50 | ```ocaml
 51 | if boolean-condition then (* code if condition is true*) else (* code if condition is false*)
 52 | ```
 53 | 
 54 | ## Loops
 55 | ### 1. While
 56 | 
 57 | ```ocaml
 58 | while boolean-condition do
 59 |   (* code *)
 60 | done
 61 | ```
 62 | 
 63 | ### 2. For
 64 | 
 65 | ```ocaml
 66 | for var = start-value to end-value do
 67 |   (* code *)
 68 | done
 69 |   
 70 | for var = start-value downto end-value do
 71 |   (* code *)
 72 | done
 73 | ```
 74 | 
 75 | ## Lists
 76 | ```ocaml
 77 | let listName= [item1;item2;item3]
 78 | ```
 79 | 
 80 | ## Tuple
 81 | ```ocaml
 82 | let tupleName  : datatype * datatype * ... = (value, value, ...);;
 83 | ```
 84 | 
 85 | ## Functions
 86 | 
 87 | ### How to define a function
 88 | 
 89 | ```ocaml
 90 | let funcName (arguments) =
 91 |     (* code *)
 92 | ```
 93 | 
 94 | ### Call a function
 95 | 
 96 | ```ocaml
 97 | funcName arguments
 98 | ```
 99 | ### Example
100 | ```ocaml
101 | (* Defining the function*)
102 | let sum a b =
103 |  (a+b)
104 | 
105 | (* calling a function)
106 | sum 3 7
107 | ```


--------------------------------------------------------------------------------
/okhttp.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: OkHttp (Java Library)
 3 | description: OkHttp is a Http client for Java based applications. It supports GZIP compression and its one of the popular http client for Android applications.
 4 | created: 2019-06-25
 5 | updated: 2019-06-25
 6 | color: #0984e3
 7 | ---
 8 | 
 9 | 
10 | OkHttp is a Http client for Java based applications. It supports GZIP compression and its one of the popular http client for Android applications.
11 | 
12 | ## Installation
13 | #### Maven
14 | ```xml
15 | <!-- https://mvnrepository.com/artifact/com.squareup.okhttp3/okhttp -->
16 | <dependency>
17 |     <groupId>com.squareup.okhttp3</groupId>
18 |     <artifactId>okhttp</artifactId>
19 |     <version>3.14.2</version>
20 | </dependency>
21 | ```
22 | #### Gradle
23 | ```groovy
24 | // https://mvnrepository.com/artifact/com.squareup.okhttp3/okhttp
25 | compile group: 'com.squareup.okhttp3', name: 'okhttp', version: '3.14.2'
26 | ```
27 | 
28 | ## GET example
29 | 
30 | ```java
31 | import okhttp3.OkHttpClient;
32 | import okhttp3.Request;
33 | import okhttp3.Response;
34 | 
35 | public class OkHttpGetExample {
36 |     public static void main(String[] args) {
37 | 
38 |         OkHttpClient client = new OkHttpClient();
39 | 
40 |         try {
41 |             Request request = new Request.Builder().url("https://httpbin.org/get").build();
42 |             Response response = client.newCall(request).execute();
43 |             String res = response.body().string();
44 |             System.out.println(res);
45 |         } catch (Exception e) {
46 |             e.printStackTrace();
47 |         }
48 | 
49 |     }
50 | }
51 | ```
52 | 
53 | ## POST Example
54 | 
55 | ```java
56 | import okhttp3.MediaType;
57 | import okhttp3.OkHttpClient;
58 | import okhttp3.Request;
59 | import okhttp3.RequestBody;
60 | import okhttp3.Response;
61 | 
62 | public class OkHttpPostExample {
63 |     
64 |     public static final MediaType JSON = MediaType.get("application/json; charset=utf-8");
65 |     
66 |     public static void main(String[] args) {
67 |         
68 |         
69 |         OkHttpClient client = new OkHttpClient();
70 | 
71 |         try {
72 |             String body = "{\n" + 
73 |                     "    \"foo\" : \"bar\"\n" + 
74 |                     "}";
75 |             Request request = new Request.Builder().url("https://httpbin.org/post").post(RequestBody.create(JSON, body)).build();
76 |             Response response = client.newCall(request).execute();
77 |             String res = response.body().string();
78 |             System.out.println(res);
79 |         } catch (Exception e) {
80 |             e.printStackTrace();
81 |         }
82 | 
83 |     }
84 | }
85 | 
86 | ```
87 | 
88 | 
89 | 


--------------------------------------------------------------------------------
/pm2.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: PM2 ( Process Manager for NodeJS )
 3 | description: PM2 is a popular NodeJS process manager that will help you run your NodeJS application in production
 4 | created: 2019-07-22
 5 | updated: 2019-07-22
 6 | ---
 7 | 
 8 | PM2 is a popular NodeJS process manager that will help you run your NodeJS application in production
 9 | 
10 | ## Installation
11 | 
12 | ```sh
13 | npm install pm2 -g
14 | ```
15 | 
16 | ## Starting application
17 | You can start the application ( let's say your starting point is app.js ) using following command
18 | ```sh
19 | pm2 start app.js
20 | ```
21 | 
22 | Following are some of the options you can use along with it
23 | 
24 | |Option|Description|
25 | |---|---|
26 | |--name|Specifying the app with a name, helps to look after it later|
27 | |--watch|application will restart on file changes|
28 | 
29 | ## Managing processes
30 | 
31 | #### Restarting the application
32 | ```sh
33 | pm2 restart app_name/app_id
34 | ```
35 | 
36 | #### Stopping the application
37 | ```sh
38 | pm2 stop app_name/app_id
39 | ```
40 | 
41 | #### Deleting the application
42 | 
43 | ```sh
44 | pm2 delete app_name/app_id
45 | ```


--------------------------------------------------------------------------------
/prop-types.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: PropTypes
  3 | description: PropTypes used to typechecking the props that are passed to a React component.  
  4 | created: 2019-09-15
  5 | updated: 2019-09-15
  6 | ---
  7 | 
  8 | PropTypes used to typechecking the props that are passed to a React component.
  9 | 
 10 | ## Syntax
 11 | 
 12 | ```javascript
 13 | import PropTypes from 'prop-types';
 14 | 
 15 | class Greetings extends React.Component {
 16 |   render() {
 17 |     return (
 18 |       <p>Hello, {this.props.name}!</p>
 19 |     );
 20 |   }
 21 | }
 22 | 
 23 | Greetings.propTypes = {
 24 |   name: PropTypes.string
 25 | };
 26 | ```
 27 | 
 28 | ## PropType Validators
 29 | 
 30 | Following code snippet shows different types of PropType Validators available. 
 31 | 
 32 | ```javascript
 33 | import PropTypes from 'prop-types';
 34 | 
 35 | MyComponent.propTypes = {
 36 |   // By default all propTypes are optional.
 37 | 
 38 |   optionalBool: PropTypes.bool, 
 39 |   optionalNumber: PropTypes.number,
 40 |   optionalString: PropTypes.string,
 41 |   optionalSymbol: PropTypes.symbol,
 42 |   optionalArray: PropTypes.array,
 43 |   optionalObject: PropTypes.object,
 44 |   optionalFunc: PropTypes.func,
 45 | 
 46 | 
 47 |   // Anything that can be rendered: numbers, strings, elements or an array or a fragment with these type values
 48 |   optionalNode: PropTypes.node,
 49 | 
 50 |   // A React element
 51 |   optionalElement: PropTypes.element,
 52 | 
 53 |   // A React element type
 54 |   optionalElementType: PropTypes.elementType,
 55 |   
 56 |   // Enums
 57 |   optionalEnum: PropTypes.oneOf(['Red', 'Green', 'Blue']),
 58 | 
 59 |   // An object that could be one of many types
 60 |   optionalUnion: PropTypes.oneOfType([
 61 |     PropTypes.string,
 62 |     PropTypes.number
 63 |   ]),
 64 | 
 65 |   // An array of a certain type, array of numbers in the following example
 66 |   optionalArrayOf: PropTypes.arrayOf(PropTypes.number),
 67 | 
 68 |   // An object with property values of a certain type, strings in the following case
 69 |   optionalObjectOf: PropTypes.objectOf(PropTypes.string),
 70 | 
 71 |   // An object taking on a particular shape
 72 |   optionalObjectWithShape: PropTypes.shape({
 73 |     name: PropTypes.string,
 74 |     age: PropTypes.number
 75 |   }),
 76 |   
 77 |   // An object with warnings on extra properties
 78 |   optionalObjectWithStrictShape: PropTypes.exact({
 79 |     name: PropTypes.string,
 80 |     age: PropTypes.number
 81 |   }),   
 82 | 
 83 |   // You can chain any of the above with `isRequired`, it shows warning if not provided 
 84 |   requiredFunc: PropTypes.func.isRequired,
 85 | 
 86 |   // A value of any data type
 87 |   requiredAny: PropTypes.any.isRequired,
 88 | 
 89 |   // You can also specify a custom validator. It should return an Error
 90 |   
 91 |   customProp: function(props, propName, componentName) {
 92 |     if (!props[propName].startsWith("#")) {
 93 |       return new Error(
 94 |         'Invalid color code `' + propName + '` supplied to' +
 95 |         ' `' + componentName + '`. Validation failed.'
 96 |       );
 97 |     }
 98 |   },
 99 | ```
100 | 


--------------------------------------------------------------------------------
/ps.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: ps Linux Command
 3 | description: ps (processes status) Linux Command is used to show information about running processes
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | ps (processes status) Linux Command is used to show information about running processes
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | ps [Option(s)]
15 | ```
16 | 
17 | ## Examples
18 | 
19 | 
20 | #### Display current shell process 
21 | ```sh
22 | $ ps
23 |   PID TTY           TIME CMD
24 | 64639 ttys000    0:00.05 -bash
25 | ```
26 | 
27 | #### Display all processes information
28 | 
29 | ```sh
30 | ps -A
31 | ```
32 | OR
33 | ```sh
34 | ps -e
35 | ```
36 | 
37 | #### Display all processes as full-format listing
38 | 
39 | ```sh
40 | ps -ef
41 | ```
42 | 
43 | #### Display user running processes
44 | 
45 | ```sh
46 | ps -x
47 | ```
48 | 
49 | #### Display process information by PID
50 | 
51 | ```sh
52 | ps -pf 1234
53 | ```
54 | 
55 | #### Display multiple processes information by PIDs
56 | 
57 | ```sh
58 | ps -pf 1234,1235,1236
59 | ```
60 | 
61 | #### Searching for a process with name
62 | 
63 | ```sh
64 |  ps -ef | grep chrome
65 | ```
66 | 
67 | ```sh
68 |  ps -ef | grep java
69 | ```
70 | 
71 | ```sh
72 |  ps -ef | grep nodejs
73 | ```


--------------------------------------------------------------------------------
/pwd.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: pwd Linux Command
 3 | description: pwd (print working directory) Linux Command is used to print full directory path of current working directory.
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | pwd (print working directory) Linux Command is used to print full directory path of current working directory.
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | pwd [Option(s)]
15 | ```
16 | ## Flags for pwd Command
17 | 
18 | pwd -L: Prints the symbolic path.
19 | pwd -P: Prints the actual path.
20 | 
21 | ## Examples
22 | 
23 | ```sh
24 | pwd #=> /Users/experimental
25 | ```
26 | 
27 | ```sh
28 | pwd -L
29 | ```
30 | 
31 | ```sh
32 | pwd -P
33 | ```
34 | 


--------------------------------------------------------------------------------
/racket.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Racket 
  3 | description: Racket cheatsheet gives you a quick reference to code syntax with examples makes it handy while coding.
  4 | created: 2020-07-03
  5 | updated: 2020-07-03
  6 | ---
  7 | 
  8 | ## Sample program
  9 | 
 10 | ```racket
 11 | #lang racket/base
 12 | (print "Hello, World!")
 13 | ```
 14 | * **`#lang`** : to define the language you are using
 15 | * **`print`** : To display the output in the console
 16 | * **`;`** : To comment a single line
 17 | * **`;;`** : To mark important comments
 18 | * **`#;`** : To comment the following s-expression
 19 | 
 20 | ## Data types
 21 | 
 22 | | Datatype | Description|
 23 | |----|----|
 24 | |Numbers| represents integers, float and complex numbers|
 25 | |Boolean| `#t` and `#f` are the two boolean literals|
 26 | |Strings| To represent sequence of characters, double quotes("") are used to represent strings|
 27 | 
 28 | ## Variables
 29 | 
 30 | Both let and define can be used to define variables.
 31 | 
 32 | ```racket
 33 | (let ([id value-expression] ...) body ...+)
 34 | 
 35 | (let proc-id ([id init-expression] ...) body ...+)
 36 | ```
 37 | 
 38 | ```racket
 39 | define id expression
 40 | ```
 41 | 
 42 | ### Example
 43 | 
 44 | ```racket
 45 | (let ([x 10]) x)
 46 | ```
 47 | 
 48 | ## Lists
 49 | ```racket
 50 | (list values)
 51 | ```
 52 | ### Example
 53 | ```racket
 54 | (list 1 2 3 4 5)
 55 | ```
 56 | |List Functions|Usage|Description
 57 | |----|----|----|
 58 | |length|(length (list 1 2 3 4 5)) | returns length of the list|
 59 | |list-ref|(list-ref (list "a" "b" "c") 0) | returns list item at an index|
 60 | |append|(append (list "a" "b") (list "c")) | to append two lists|
 61 | |reverse| (reverse (list "a" "b" "c"))| to reverse a list|
 62 | |member|(member "g" (list "a" "b" "c"))| checks if an element is present in a list|
 63 | 
 64 | ## Conditional statements
 65 | 
 66 | ### 1. If
 67 | ```racket
 68 | (if cond-expr then-expr)
 69 | ```
 70 | 
 71 | ### 2. If-else
 72 | ```racket
 73 | (if cond-expr then-expr else-expr)
 74 | ```
 75 | 
 76 | ## Loops
 77 | ### 1. For
 78 | 
 79 | ```racket
 80 | (for (for-clause ...) body-or-break ... body)
 81 | ```
 82 | where 
 83 | 
 84 | **for-clause** = [id seq-expr] | [(id ...) seq-expr] | #:when guard-expr | #:unless guard-expr | break-clause
 85 |  	 	 	 	  	 	 	 	 
 86 | **body-or-break**= body | break-clause
 87 | 
 88 | 
 89 | ## Functions
 90 | 
 91 | ```racket
 92 | (def fn functionName args body ...+)
 93 | ```
 94 | 
 95 | ### Example
 96 | ```racket
 97 | #lang racket/base
 98 | (define (square y) (* y y))
 99 | (square 5)
100 | ```
101 | 
102 | ## Procedures
103 | ```racket
104 | (lambda (argument-id ...)
105 |   body ...+)
106 | ```


--------------------------------------------------------------------------------
/react-helmet.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: React Helmet (React Component Library)
 3 | description: React Helmet is a React library used to change Document Head tags like title, meta etc.,
 4 | created: 2019-07-14
 5 | updated: 2019-07-14
 6 | ---
 7 | 
 8 | 
 9 | React Helmet is a React library used to change Document Head tags like title, meta etc.,
10 | 
11 | ## Installation
12 | 
13 | ```sh
14 | npm install react-helmet
15 | ```
16 | 
17 | ## Example usage
18 | 
19 | ```javascript
20 | import React from "react";
21 | import { Helmet } from "react-helmet";
22 |  
23 | class TermsAndConditions extends React.Component { 
24 |     render (){
25 |         return(
26 |              <>
27 |                 {/* Helmet code for Head content */}
28 |                 <Helmet>
29 |                     <title>{'Terms and Conditions'}</title>
30 |                 </Helmet>
31 | 
32 |                 {/* Component content*/}
33 |                 <h1> Terms and Conditions </h1>
34 |                 <p>
35 |                     ... 
36 |                     .....
37 |                     .......
38 |                 </p>
39 | 
40 |              </>   
41 |         )
42 |     }
43 | }
44 | 
45 | export default TermsAndConditions;
46 | 
47 | ```
48 | 
49 | ## Possible tags 
50 | 
51 | ```xml
52 | <Helmet>
53 |     <meta charSet="utf-8" />
54 |     <title>{'Page Title'}</title>
55 |     <meta name="description" content="description of the page" />
56 | 
57 |     <script src="http://foo.com/bar.js" type="text/javascript" />
58 |     <link rel="stylesheet" href="http://foo.com/bar.css" />
59 | </Helmet>
60 | ```


--------------------------------------------------------------------------------
/reactjs.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: React JS
  3 | description: React JS cheatsheet contains useful code syntax with examples which is handy while coding.
  4 | created: 2020-07-23
  5 | updated: 2020-07-23
  6 | ---
  7 | 
  8 | ## Create React App
  9 | 
 10 | ```js
 11 | npx create-react-app my-app
 12 | ```
 13 | ## Import
 14 | 
 15 | ```js
 16 | import React from 'react'
 17 | import React, {Component} from 'react'; //multiple imports
 18 | ```
 19 | 
 20 | ## Components
 21 | 
 22 | ### Class component
 23 | 
 24 | ```js
 25 | class Greetings extends React.Component {
 26 |   render() {
 27 |     return <h1>Hello, {this.props.name}</h1>;
 28 |   }
 29 | }
 30 | ```
 31 | ### Functional component
 32 | 
 33 | ```js
 34 | function Greetings(props) {
 35 |   return <h1>Hello, {props.name}</h1>;
 36 | }
 37 | ```
 38 | 
 39 | ## Props
 40 | 
 41 | ```js
 42 | function Greetings(props) {
 43 |   return <h1>Hello {props.name}</h1>;
 44 | }
 45 | 
 46 | function App() {
 47 |   return (
 48 |     <div>
 49 |       <Greetings name="foo" />
 50 |       <Greetings name="bar" />
 51 |     </div>
 52 |   );
 53 | }
 54 | ```
 55 | Note: Props are read-only
 56 | 
 57 | ## Render
 58 | 
 59 | ```js
 60 | render() {
 61 |   return <div />;
 62 | }
 63 | ```
 64 | 
 65 | ## Hooks
 66 | 
 67 | Below is a sample code, which increases the count value when you click `+` and decreases the count value when you click `-`.
 68 | 
 69 | ```js
 70 | import React, { useState } from "react";
 71 | 
 72 | function App() {
 73 |   const [count, setCount] = useState(0);
 74 | 
 75 |   return (
 76 |     <div className="container">
 77 |       <h1>{count}</h1>
 78 |       <button onClick={()=>setCount(count-1)}>-</button>
 79 |       <button onClick={()=>setCount(count+1)}>+</button>
 80 |     </div>
 81 |   );
 82 | }
 83 | 
 84 | export default App;
 85 | ```
 86 | useEffect()-
 87 | The next most useful Hook you will encounter is the useEffect Hook. It performs a function whenever a specified state has changed.
 88 | 
 89 | ```js
 90 | function House() {
 91 |   const [color, setColor] = useState("white");
 92 |   const [door, setDoor] = useState(0); //initialize door as 0
 93 | 
 94 | //add 1 to the current value of door on every button click
 95 |   const addDoor = () => {
 96 |     setDoor(door + 1);
 97 |   };
 98 | 
 99 | //finally, trigger the function to print the door value whenever door is updated
100 |   useEffect(() => {
101 |     console.log(`Door count: ${door}`)
102 |   }, [door]);
103 | 
104 |   return (
105 |     <div>
106 |       <h2>This is a {color} house</h2>
107 |       <button onClick={addDoor}>Add a Door</button>
108 |     </div>
109 |   );
110 | }
111 | ```
112 | 
113 | ## Conditional Rendering
114 | 
115 | ### Ternary Operator
116 | 
117 | ```js
118 |  <button type="submit">{isloggedin ? "Login" : "Register"}</button>
119 | ```
120 | 
121 | ### Usage of && 
122 | 
123 | `&&` also used to execute a block of code only if condition is true.
124 | 
125 | ```js
126 |       {!isloggedin && (
127 |             <button type="submit">{isloggedin ? "Login" : "Register"}</button>
128 |       )}
129 | ```
130 | 
131 | ## Forms
132 | 
133 | Below is example of a simple form which displays the given name along with Hello. For example, if you give `Foo` in the input field, then when you click submit button it should display `Hello Foo`.
134 | 
135 | ```js
136 | import React, { useState } from "react";
137 | 
138 | function App() {
139 |   const [name, setName] = useState("");
140 |   const [displayName, setDisplayName] = useState("");
141 | 
142 |   function handleClick(event) {
143 |     setDisplayName(name);
144 |     event.preventDefault();
145 |   }
146 | 
147 |   return (
148 |     <div className="container">
149 |       <h1>Hello {displayName}</h1>
150 |       <form>
151 |         <input
152 |           placeholder="Enter your name?"
153 |           value={name}
154 |           onChange={(event)=>setName(event.target.value)}
155 |         />
156 |         <button type="submit" onClick={handleClick}>Submit</button>
157 |       </form>
158 |     </div>
159 |   );
160 | }
161 | 
162 | export default App;
163 | ```
164 | 
165 | ### Note
166 | 
167 | When you click a submit button, usually page gets refreshed. You can prevent this by preventing the default settings.
168 | 
169 | ```js
170 | event.preventDefault();
171 | ```
172 | 


--------------------------------------------------------------------------------
/redis.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Redis
 3 | description: Redis is an in-memory data structure store, used as a database, cache and message broker.
 4 | created: 2018-09-22
 5 | updated: 2018-09-22
 6 | ---
 7 | 
 8 | ### Hash
 9 | 
10 | ```sh
11 | HSET colors white fffff
12 | HSET colors black 000000
13 | HSET colors blue 0000FF
14 | HGET colors white
15 | HDEL colors white
16 | ```
17 | 
18 | ### List
19 | 
20 | ```sh
21 | LPUSH tasks task1
22 | LPUSH tasks task2
23 | RPUSH tasks task3
24 | RPOP tasks # removes and get last element in list
25 | LPOP tasks # removes and get first element in list
26 | LRANGE tasks 5 10 # returns elements in specified range
27 | BRPOP tasks # blocking RPOP
28 | BLPOP tasks # blocking LPOP
29 | LLEN tasks # list length
30 | ```
31 | 
32 | ### Set
33 | 
34 | ```sh
35 | SADD colors white
36 | SADD colors black
37 | SADD colors black
38 | SADD colors blue
39 | SREM colors white
40 | SMEMBERS myset
41 | ```
42 | 
43 | ### SortedSets
44 | 
45 | ```
46 | Takes score and sort by that
47 | ```
48 | 
49 | ### String
50 | 
51 | ```sh
52 | SET welcomeMessage "Hello"
53 | APPEND welcomeMessage " World"
54 | 
55 | SET masterServer host123 EX 60 NX # EX - Set the specified expire time, in seconds
56 |                                   # PX - Set the specified expire time, in milliseconds
57 |                                   # NX - Only set the key if it does not already exist.
58 |                                   # XX - Only set the key if it already exist.
59 | ```
60 | 
61 | ### MISC
62 | 
63 | ```sh
64 | FLUSHALL
65 | FLUSHDB
66 | ```
67 | 
68 | ### Use Cases
69 | 
70 | * Cache layer
71 | * Distributed Locking
72 | * Pub/Sub
73 | * Async communication
74 | * Batch processing (Jobs in queues)
75 | * session
76 | * Redis + Elasticsearch
77 | * Redis + Logstash
78 | * Leaderboards ( Counting )
79 | * Geospatial queries


--------------------------------------------------------------------------------
/request.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Request (Javascript Library)
 3 | description: Request is a Javascript library which is used to make rest/API calls to the other servers, return value of the request is a callback
 4 | created: 2019-09-29
 5 | updated: 2019-09-29
 6 | ---
 7 | Request is a Javascript library which is used to make rest/API calls to the other servers, return value of the request is a callback
 8 | 
 9 | ## Usage
10 | 1 Using NPM
11 | 
12 | ```sh
13 | npm i request
14 | ```
15 | 
16 | ## Hitting rest methods
17 | 
18 | #### GET
19 | ``` javascript
20 | var request = require("request");
21 | 
22 | var options = { method: 'GET',
23 |                 url: 'https://jsonplaceholder.typicode.com/todos/1'
24 |               };
25 | 
26 | request(options, function (error, response, body) {
27 |   if (error) throw new Error(error);
28 | 
29 |   console.log(body);
30 | });
31 | ```
32 | 
33 | #### POST
34 | 
35 | ``` javascript
36 | var request = require("request");
37 | 
38 | var options = { method: 'POST',
39 |   url: 'https://jsonplaceholder.typicode.com/todos',
40 |   headers: { 
41 |       'content-type': 'application/json' 
42 |   },
43 |   body: {
44 |     foo: 'bar'
45 |   },
46 |   json: true 
47 | };
48 | 
49 | request(options, function (error, response, body) {
50 |   if (error) throw new Error(error);
51 | 
52 |   console.log(body);
53 | });
54 | ```
55 | 
56 | ## Streaming
57 | 
58 | We can stream response to a file using request
59 | ``` javascript
60 | request('https://jsonplaceholder.typicode.com/todos/1').pipe(fs.createWriteStream('todo.txt'))
61 | ```
62 | We can also stream a file to the PUT/POST method using request method.
63 | ```javascript
64 | fs.createReadStream('file.json').pipe(request.put('http://mysite.com/obj.json'))
65 | ```
66 | #### Promises and async/await
67 | 
68 | We can also return promises instead of callbacks, for this we need to use interface wrapper for request. We can also use async/await using request.
69 | 
70 | 


--------------------------------------------------------------------------------
/rm.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: rm Linux Command
 3 | description: rm (remove) Linux Command is used to remove objects such as files, directories, symbolic links, device nodes, pipes and sockets from the file system. 
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | rm (remove) Linux Command is used to remove objects such as files, directories, symbolic links, device nodes, pipes and sockets from the file system.
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | rm [Option(s)] [File(s) to remove]
15 | ```
16 | 
17 | ## Examples
18 | 
19 | #### Removing a single file
20 | ```sh
21 | rm file1.txt #=> removes file1.txt
22 | ```
23 | 
24 | #### Removing multiple files
25 | ```sh
26 | rm file1.txt file2.txt #=> removes file1.txt and file2.txt
27 | ```
28 | 
29 | #### Interactive deletion
30 | 
31 | ```sh
32 | rm -i readme.txt
33 | remove readme.txt? Y 
34 | ```
35 | 
36 | #### Force deletion (Removes even if the file is write protected)
37 | 
38 | ```sh
39 | rm readme.txt
40 | ```
41 | 
42 | #### Delete recusively
43 | 
44 | ```sh
45 | rm -r *
46 | ```


--------------------------------------------------------------------------------
/rmdir.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: rmdir Linux Command
 3 | description: rmdir Linux Command is used to remove an empty directory.
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | rmdir Linux Command is used to remove an empty directory.
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | rmdir [Option(s)] [name-of-directory]
15 | ```
16 | 
17 | 
18 | ## Options
19 | 
20 | |Option| Description|
21 | |---|---|
22 | |-p| removes parent directories if they are also empty|
23 | 
24 | ## Examples
25 | 
26 | 
27 | #### Removing an empty directory
28 | ```sh
29 | rmdir movies #=> removes movies directory
30 | ```


--------------------------------------------------------------------------------
/ruby.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Ruby 
  3 | description: Ruby cheatsheet contains useful code syntax with examples which is handy while coding.
  4 | created: 2020-06-08
  5 | updated: 2020-06-08
  6 | ---
  7 | 
  8 | ## Basics
  9 | 
 10 | ### Sample program
 11 | ```ruby
 12 | puts "Hello, World!"
 13 | ```
 14 | * ***puts*** :  Used to print the given text to the console.
 15 | * `#` : Single line Comment
 16 | * `=begin`
 17 | Multi 
 18 | line 
 19 | comment
 20 | `=end`
 21 | 
 22 | ## Variables
 23 | 
 24 | ### 1. Global variables
 25 | 
 26 | Begins with `$` and will have global scope
 27 | ```ruby
 28 | $var_scope = "GLOBAL"
 29 | ```
 30 | 
 31 | ### 2. Local variables
 32 | 
 33 | Begins with a `lowercase letter` or `underscore (_)` and will have scope limited to block of it's initialization.
 34 | ```ruby
 35 | _greeting = "Hello"
 36 | age = 21
 37 | ```
 38 | ### 3. Instance variables
 39 | 
 40 | Belongs to one instance of a class and starts with a `@` sign.
 41 | ```ruby
 42 | @name = "OneCompiler"
 43 | ```
 44 | ### 4. Class variables
 45 | 
 46 | Belongs to the entire class and starts with `@@`.
 47 | 
 48 | ```ruby
 49 | @@id = 111
 50 | ```
 51 | 
 52 | ## Operators
 53 | |Type|Operators|
 54 | |----|----|
 55 | | Arithmetic Operators| + , - , * , / , % , ** |
 56 | | Comparision Operators| == , != , > , >= , < , <= , <=>, .eql?, ===, equal? |
 57 | | Bitwise Operators| & , ^ , \| , ^ , ~ , << , >> |
 58 | | Logical Operators| && , \|\| , ! , and , or, not|
 59 | | Assignment Operators|= , += , -= , *= , /= , %= , **= |
 60 | | Ternary Operators | ? :|
 61 | | Range Operators | .. , ...|
 62 | | Special Operators | defined?, . , :: |
 63 | 
 64 | ## Arrays
 65 | 
 66 | Array is a collection of data items and they no need to be of same type.
 67 | 
 68 | ```ruby
 69 | array_name = Array.new(size)
 70 | # or
 71 | array_name = Array.new
 72 | ```
 73 | ### Example
 74 | ```ruby
 75 | arr = [ "Good", "morning", 9, 5.32 , true]
 76 | ```
 77 | ## Hashes
 78 | 
 79 | Hashes represents key-value pairs. `=>` is used to assign value to it's key. 
 80 | 
 81 | ```ruby
 82 | hsh = nationalGame = { "Australia" => "Cricket", "Japan" => "Wrestling", "NewZealand" => "Rugby","USA" => "Baseball"}
 83 | ```
 84 | 
 85 | ## Conditional Statements
 86 | 
 87 | ### 1. If
 88 | 
 89 | ```ruby
 90 | if conditional-expression 
 91 |     #code
 92 | end
 93 | ```
 94 | ### 2. If-else
 95 | 
 96 | ```ruby
 97 | if conditional-expression
 98 |     #code
 99 | else 
100 |     #code
101 | end
102 | ```
103 | ### 3. Nested If-else
104 | 
105 | ```ruby
106 | if conditional-expression
107 |     #code
108 | elsif conditional-expression
109 |     #code
110 | else 
111 |     #code
112 | end
113 | ```
114 | 
115 | ### 4. Case
116 | 
117 | ```ruby
118 | case exp
119 | [when exp [then]
120 |    #code ]...
121 | [else
122 |    #code ]
123 | end
124 | ```
125 | 
126 | ## Loops
127 | 
128 | ### 1. For
129 | 
130 | ```ruby
131 | for variable [, variable ...] in range [do]
132 |    #code
133 | end
134 | ```
135 | 
136 | ### 2. While
137 | 
138 | ```ruby
139 | while conditional-expression [do]
140 |    #code
141 | end
142 | ```
143 | 
144 | ### 3. Until
145 | 
146 | ```ruby
147 | until conditional-expression [do]
148 |    #code
149 | end
150 | ```
151 | ## Methods
152 | 
153 | ```ruby
154 | def methodName [( [arg [= default]]...[, * arg [, &expr ]])]
155 |    #code  
156 | end 
157 | ```
158 | ### Example
159 | ```ruby
160 | def sum(x , y)
161 |    sum = x+y
162 |    puts "Sum: #{sum}"
163 | end
164 | sum(10,20) # passing parameters to method sum
165 | ```


--------------------------------------------------------------------------------
/rust.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Rust 
  3 | description: Rust cheatsheet contains useful code syntax with examples which is handy while coding.
  4 | created: 2022-10-04
  5 | updated: 2022-10-05
  6 | ---
  7 | 
  8 | ## Basics
  9 | 
 10 | ### Sample program
 11 | ```rust
 12 | fn main(){
 13 |    println!("Hello World");
 14 | }
 15 | ```
 16 | * `//` : Single line Comment
 17 | * /* This is a Multi-line comment */
 18 | 
 19 | ## Variables
 20 | 
 21 | 
 22 | Begins with `let` 
 23 | ```rust
 24 | let a = "hello";
 25 | ```
 26 | ### Mutable
 27 | ```rust
 28 | fn main() {
 29 |     let mut a:i32 = 10;
 30 |     println!("{}",a);
 31 |     a = 20;
 32 |     println!("{}",a);
 33 | }
 34 | ```
 35 | 
 36 | ## Constants
 37 | Begins with `const` 
 38 | ```rust
 39 | const USER_LIMIT:i32 = 100;    // Declare a integer constant
 40 | const PI:f32 = 3.14;           //Declare a float constant
 41 | ```
 42 | 
 43 | ## Operators
 44 | |Type|Operators|
 45 | |----|----|
 46 | | Arithmetic Operators| + , - , * , / , %  |
 47 | | Relational Operators| == , != , > , >= , < , <= |
 48 | | Bitwise Operators| & , ^ , \| , << , >> |
 49 | | Logical Operators| && , \|\| , ! |
 50 | 
 51 | 
 52 | ## Conditional Statements
 53 | 
 54 | ### 1. If
 55 | 
 56 | ```rust
 57 | if conditional-expression {
 58 |     #code
 59 | }
 60 | ```
 61 | ### 2. If-else
 62 | 
 63 | ```rust
 64 | if conditional-expression {
 65 |     #code
 66 | }
 67 | else {
 68 |     #code
 69 | }
 70 | ```
 71 | ### 3. Nested If-else
 72 | 
 73 | ```rust
 74 | if conditional-expression {
 75 |     #code
 76 | }
 77 | else if conditional-expression {
 78 |     #code
 79 | }
 80 | else {
 81 |     #code
 82 | }
 83 | ```
 84 | 
 85 | ## Loops
 86 | 
 87 | ### 1. For
 88 | 
 89 | ```rust
 90 | for temp_variable in lower_bound..upper_bound {
 91 |    #code
 92 | }
 93 | ```
 94 | 
 95 | ### 2. While
 96 | 
 97 | ```rust
 98 | while conditional-expression {
 99 |    #code
100 | }
101 | ```
102 | 
103 | ## Methods
104 | 
105 | ```rust
106 | fn function_name(param1,param2..paramN) {
107 |    #code
108 | }
109 | ```
110 | ### Example
111 | ```rust
112 | fn fn_hello(){
113 |    println!("hello from function fn_hello ");
114 | }
115 | 
116 | fn main(){
117 |    //calling a function
118 |    fn_hello();
119 | }
120 | ```
121 | 
122 | ## Strings
123 | 
124 | String literals in Rust are used when the value of a string is known at compile time.
125 | 
126 | ```rs
127 | fn main() {
128 |    let site:&str="Working";
129 |    let quality:&str = "Excellent";
130 |    println!("site is : {} quality :{}",site,quality);
131 | }
132 | ```
133 | String literals are static by default. This means that string literals are guaranteed to be valid for the duration of the entire program.
134 | 
135 | ## Arrays
136 | 
137 | Syntax for declaring,initializing and displaying an array in Rust.
138 | 
139 | ```rs
140 | fn main(){
141 |    let arr1:[i32;4] = [10,20,30,40];
142 |    let arr2:[i32;4] = [1,2,3,4];
143 |    println!("array1 is {:?}",arr1);
144 |    println!("array2 is :{}",arr2);
145 | }
146 | ```
147 | 
148 | ## Tuples
149 | 
150 | Tuples are a compound datatype and have a fixed length - once declared they cannot grow or shrink in size. Indexing in Tuples start from zero
151 | 
152 | ```rs
153 | fn main() {
154 |    let tuple:(i32,f64,u8) = (-325,4.9,22);
155 |    println!("integer is :{:?}",tuple.0);
156 |    println!("float is :{:?}",tuple.1);
157 |    println!("unsigned integer is :{:?}",tuple.2);
158 | }
159 | ```
160 | 
161 | ## Structures
162 | 
163 | A structure defines data as a key-value pair.The struct keyword is used to declare a structure. Since structures are statically typed, every field in the structure must be associated with a data type.
164 | 
165 | ```rs
166 | struct student {
167 |    name:String,
168 |    Grade:String,
169 |    age:u32
170 | }
171 | fn main() {
172 |    //initialize a structure
173 |    let st1 = student {
174 |       Grade:String::from("A+"),
175 |       name:String::from("John"),
176 |       age:20
177 |    };
178 |    let st2 = student{
179 |       Grade:String::from("B+"),
180 |       name:String::from("Jack"),
181 |       age:19
182 |    };
183 | }
184 | ```
185 | 
186 | ## Enums
187 | 
188 | In Rust programming, when we have to select a value from a list of possible variants we use enumeration data types. An enumerated type is declared using the enum keyword.
189 | 
190 | ```rs
191 | enum Roles {
192 |    Developer,Designer
193 | }
194 | fn main() {
195 |    let m1 = Roles::Developer;
196 |    let m2 = Roles::Designer;
197 | 
198 |    println!("{:?}",m1);
199 |    println!("{:?}",m2);
200 | }
201 | ```
202 | 
203 | 
204 | 


--------------------------------------------------------------------------------
/scala.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: Scala 
  3 | description: Quick reference to scala cheat sheet which will increase your productivity as it contains useful syntax and is very handy while coding. 
  4 | created: 2020-06-25
  5 | updated: 2020-06-25
  6 | ---
  7 | 
  8 | ## Sample program
  9 | 
 10 | ```java
 11 | object HelloWorld {
 12 | 	def main(args: Array[String]): Unit = {
 13 | 	println("Hello, World!")
 14 | 	}
 15 | }
 16 | ```
 17 | * ***object*** :  Object is a instance of a class. In Scala, everything is considered as objects.
 18 | * ***def*** : def is used for function declaration
 19 | * ***main*** : entry point of the program
 20 | * ***println*** : prints data to the console.
 21 | * `//` : Single line comment
 22 | * `/*` Multi
 23 |     Line
 24 |     comment `*/`
 25 | 
 26 | ## Data types
 27 | 
 28 | | Data type | Description | Range | Size|
 29 | |---|---|---|---|
 30 | | int| used to store whole numbers|-2,147,483,648 to 2,147,483,647|4 bytes|
 31 | |short| used to store whole numbers|-32,768 to 32,767| 2 bytes|
 32 | |long| used to store whole numbers|-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807| 8 bytes|
 33 | |byte| used to store whole numbers|-128 to 127| 1 byte|
 34 | |float| used to store fractional numbers|6 to 7 decimal digits| 4 bytes|
 35 | |double| used to store fractional numbers|15 decimal digits| 8 bytes|
 36 | |boolean| can either store true or false |either true or false| 1 bit|
 37 | |char|used to store a single character|one character|2 bytes|
 38 | |string | used to store strings|sequence of characters|2bytes per character|
 39 | 
 40 | ## Variables
 41 | 
 42 | ```java
 43 | var varName = value
 44 | val  varName = value
 45 | varName = value
 46 | var varName : DataType = value
 47 | ```
 48 | 
 49 | ## Operators
 50 | 
 51 | |Type|Operators|
 52 | |----|----|
 53 | | Arithmetic Operators| + , - , * , / , %  |
 54 | | Comparision Operators| == , != , > , >= , < , <= |
 55 | | Bitwise Operators| & , ^ , \| , ^ , ~ , << , >> , >>>|
 56 | | Logical Operators| && , \|\| , !|
 57 | | Assignment Operators|= , += , -= , *= , /= , %= , &= , ^= , \|= , <<= , >>= |
 58 | 
 59 | ## Conditional Statements
 60 | 
 61 | ### 1. If
 62 | 
 63 | ```java
 64 | if(conditional-expression)
 65 | {
 66 |     //code
 67 | }
 68 | ```
 69 | ### 2. If-else
 70 | 
 71 | ```java
 72 | if(conditional-expression)
 73 | {
 74 |     //code
 75 | } else {
 76 |     //code
 77 | }
 78 | ```
 79 | ### 3. If-else-if ladder
 80 | 
 81 | ```java
 82 | if(conditional-expression-1)
 83 | {
 84 |     //code
 85 | } else if(conditional-expression-2) {
 86 |     //code
 87 | } else if(conditional-expression-3) {
 88 |     //code
 89 | }
 90 | ....
 91 | else {
 92 |     //code
 93 | }
 94 | ```
 95 | ## Loops
 96 | 
 97 | ### 1. For
 98 | 
 99 | ```java
100 | for(var <- range){  
101 | //code  
102 | } 
103 | ```
104 | ### 2. For loop Using until 
105 | 
106 | ```java
107 | for( var <- initialValue until maxValue ){  
108 |     //code  
109 | }
110 | ```
111 | 
112 | ### 3. For loop filtering
113 | 
114 | ```java
115 | for( var <- initialValue until maxValue if condition){  
116 |   //code
117 | }
118 | ```
119 | ### 4. For loop for collections like lists, sequence etc
120 | 
121 | ```java
122 | for( varName <- Collections){             
123 |   //code
124 | }
125 | ```
126 | ### 5. While
127 | 
128 | ```java
129 | while(condition){  
130 | //code 
131 | }  
132 | ```
133 | ### 6. Do-while
134 | 
135 | ```java
136 | do{  
137 | //code 
138 | }while(condition); 
139 | ```
140 | 
141 | ## Arrays
142 | Array is a collection of similar data which is stored in continuous memory addresses.
143 | 
144 | ### Declaring 1-D array
145 | 
146 | ```java
147 | var arrayName:Array[datatype] = new Array[datatype](size)
148 | 
149 | //or
150 | 
151 | var arrayName = new Array[datatype](size)
152 | ```
153 | 
154 | ### Declaring 2-D array
155 | 
156 | ```java
157 | var arrName = ofDim[datatype](rowsize,colSize)
158 | ```
159 | ### Example
160 | 
161 | ```java
162 |  var arr1 = Array(1, 2, 3, 4, 5)
163 | ```
164 | 
165 | ## Functions
166 | 
167 | ### How to declare a Function
168 | 
169 | ```java
170 | def functionName ([argumentsList]) : [return type]
171 | ```
172 | ### How to define a Function
173 | ```java
174 | def functionName ([argumentsList]) : [return type] [=] {
175 |    // code
176 |    return [expr]
177 | }
178 | ```
179 | ### How to call a Function
180 | 
181 | ```java
182 | function_name (argumentsList)
183 | ```


--------------------------------------------------------------------------------
/scp.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: SCP (secure copy) command
 3 | description: SCP command is used to securely copy files btween two locations i.e local to a remote location or remote location to local, you can also transfer from one remote location to another remote location. 
 4 | created: 2019-06-20
 5 | updated: 2019-06-20
 6 | color: #7f8c8d
 7 | ---
 8 | 
 9 | 
10 | SCP command is used to securely copy files btween two locations i.e local to a remote location or remote location to local, you can also transfer from one remote location to another remote location.
11 | 
12 | ## Local to remote location
13 | ```sh
14 | scp /path/to/local/file user@remote_host:/path/in/remote/location
15 | ```
16 | 
17 | ## Remote location to local
18 | ```sh
19 | scp user@remote_host:/path/in/remote/location /path/to/local/file 
20 | ```
21 | 
22 | ## Copying multiple files
23 | ```sh
24 | scp /path/to/local/file1 /path/to/local/file2 user@remote_host:/path/in/remote/location
25 | ```
26 | 
27 | ## Copying entire directory 
28 | ```sh
29 | scp -r /path/to/local/directory user@remote_host:/path/in/remote/location
30 | ```
31 | 
32 | ## SCP Options
33 | |Option|Description|Example|
34 | |---|---|---|
35 | |`-C`|Force SCP to compress data|`scp -C foo.txt ubuntu@1.1.1.1:/home/ubuntu/ `|
36 | |`-r`|recursively copy files from directories||
37 | |`-v`|verbose mode to see transfer details|`scp -v foo.txt ubuntu@1.1.1.1:/home/ubuntu/ `|
38 | |`-l`|limit the bandwidth|`scp -l 100 foo.txt ubuntu@1.1.1.1:/home/ubuntu/ `|


--------------------------------------------------------------------------------
/search-engins.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: Search Engines
 3 | description: World's top Search Engins as of today
 4 | updated: 2019-08-13
 5 | updated: 2022-10-22
 6 | ---
 7 | 
 8 | World's top Search Engins as of today
 9 | 
10 | | Search Engine | Market Share | Website|
11 | |--------|--------|--------|
12 | |Google|92.42%|https://www.google.com/|
13 | |Bing|3.45%|https://www.bing.com/|
14 | |Yahoo|1.22%|https://www.yahoo.com/|
15 | |Yandex|0.79%|https://yandex.com/|
16 | |Baidu|0.65%|https://www.baidu.com/|
17 | |Ask.com|NA|http://www.ask.com/|
18 | |AOL.com|NA|https://www.aol.com/|
19 | |Wolframalpha|NA|https://www.wolframalpha.com/|
20 | |DuckDuckGo|NA|https://duckduckgo.com/|
21 | |Internet Archive|NA|https://archive.org/|
22 | 


--------------------------------------------------------------------------------
/tail.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: tail Linux Command
  3 | description: tail Linux Command is used to display tail end of a text file/ piped data.
  4 | created: 2019-09-13
  5 | updated: 2019-09-13
  6 | ---
  7 | 
  8 | tail Linux Command is used to display tail end of a text file/ piped data.
  9 | 
 10 | 
 11 | ## Syntax
 12 | 
 13 | ```sh
 14 | tail [options] file-name
 15 | ```
 16 | 
 17 | ## Examples
 18 | 
 19 | For example consider the following file
 20 | 
 21 | ```sh
 22 | $ cat readme.txt 
 23 | line1
 24 | line2
 25 | line3
 26 | line4
 27 | line5
 28 | line6
 29 | line7
 30 | line8
 31 | line9
 32 | line10
 33 | line11
 34 | line12
 35 | line13
 36 | line14
 37 | line15
 38 | ```
 39 | 
 40 | ```sh
 41 | $ tail readme.txt
 42 | line6
 43 | line7
 44 | line8
 45 | line9
 46 | line10
 47 | line11
 48 | line12
 49 | line13
 50 | line14
 51 | line15
 52 | ```
 53 | 
 54 | ```
 55 | Note: head by default shows first 10 lines
 56 | ```
 57 | 
 58 | ### Showing last 2 lines
 59 | 
 60 | ```sh
 61 | $ tail -n 2 readme.txt
 62 | line14
 63 | line15
 64 | 
 65 | ```
 66 | 
 67 | ### Showing last 5 lines
 68 | 
 69 | ```sh
 70 | $ tail -n 5 readme.txt
 71 | line11
 72 | line12
 73 | line13
 74 | line14
 75 | line15
 76 | ```
 77 | 
 78 | ### Showing from multiple files
 79 | ```sh
 80 | $ tail -n 2 readme.txt readme-2.txt
 81 | ==> readme.txt <==
 82 | line14
 83 | line15
 84 | 
 85 | ==> readme-2.txt <==
 86 | line14
 87 | ```
 88 | 
 89 | ### Showing from all files that are starting with readme
 90 | ```sh
 91 | $ tail -n 2 readme*
 92 | ==> readme-1.txt <==
 93 | line14
 94 | line15
 95 | ==> readme-2.txt <==
 96 | line14
 97 | line15
 98 | ==> readme.txt <==
 99 | line14
100 | line15
101 | ```


--------------------------------------------------------------------------------
/tar-gz.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: tar.gz
 3 | description: tar.gz compressing and extracting
 4 | created: 2019-06-15
 5 | updated: 2019-06-15
 6 | color: #7f8c8d
 7 | ---
 8 | 
 9 | ### Compress a file/folder
10 | ```sh
11 | tar -zcvf <zip_file_name>.tar.gz /path/to/folder/or/file
12 | ```
13 | 
14 | ### Uncompress a file/folder
15 | ```sh
16 | tar xvf <zip_file_name>.tar.gz /optional/folder/path/to/keep/unzip/content
17 | ```


--------------------------------------------------------------------------------
/tcl.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: TCL
  3 | description: Quick reference to TCL cheat sheet which contains useful syntax and is very handy while coding. 
  4 | created: 2020-06-26
  5 | updated: 2020-06-26
  6 | ---
  7 | 
  8 | ## Sample program
  9 | 
 10 | ```c
 11 | set name [gets stdin]
 12 | puts "Hello $name"
 13 | ```
 14 | * ***set*** : To set data to a variable
 15 | * ***gets stdin*** : to read input data from Console
 16 | * ***puts*** : prints data to the console.
 17 | * `#` : Single line comment
 18 | 
 19 | ## Variables
 20 | 
 21 | ```c
 22 | set name onecompiler
 23 | ```
 24 | ## Operators
 25 | 
 26 | | Operator type | Description|
 27 | |----|-----|
 28 | | Arithmetic Operator|+ , - , * , / , %|
 29 | | comparision Operator| < , > , <= , >=, != , ==|
 30 | | Bitwise Operator| & , ^ , \|, <<, >>|
 31 | | Logical Operator| && , `\|\|`, ! |
 32 | | Ternary Operator| ? : |
 33 | 
 34 | ## Conditional Statements
 35 | 
 36 | ### 1. If-Else
 37 | 
 38 | ```c
 39 | if(conditional-expression) {
 40 |    #code
 41 | } else {
 42 |    #code
 43 | }
 44 | ```
 45 | 
 46 | ### 2. Switch
 47 | 
 48 | ```c
 49 | switch(conditional-expression) {    
 50 | value1 {     
 51 |  # code
 52 | }    
 53 | value1 {     
 54 |  # code
 55 | }    
 56 | ...
 57 | default {
 58 | # code
 59 | } 
 60 | ```
 61 | 
 62 | ## Loops
 63 | 
 64 | ### 1. For
 65 | 
 66 | ```c
 67 | for{start}{test}{next}{  
 68 |   # code  
 69 | } 
 70 | ```
 71 | ### 2. While
 72 | 
 73 | ```c
 74 | while(condition) {  
 75 |  # code 
 76 | }  
 77 | ```
 78 | 
 79 | ## Arrays
 80 | 
 81 | ```c
 82 | set ArrayName(Index) value
 83 | ```
 84 | ## Lists
 85 | 
 86 | ```c
 87 | set listName { i1 i2 i3 .. in }
 88 | # or
 89 | set listName [list i1 i2 i3]
 90 | # or 
 91 | set listName [split "items which separated by a character" split_character]
 92 | ```
 93 | 
 94 | ## Dictionary
 95 | 
 96 | Dictionary is a collection of key-value pairs.
 97 | 
 98 | ```c
 99 | dict set dictName key value
100 | # or 
101 | dict create dictName key1 value1 key2 value2 .. keyn valuen
102 | ```
103 | ## Procedures
104 | 
105 | ```c
106 | proc procedureName {arguments} {
107 |    # code
108 | }
109 | ```
110 | 
111 | ## File Handling
112 | 
113 | ### Opening a file
114 | 
115 | ```c
116 | open fileName Mode
117 | ```
118 | 
119 | |Mode|Description|
120 | |----|----|
121 | |"r"  |  Read-only(default mode)|
122 | |"r+" |  Read-write, File must be present already. |
123 | |"w"  |  Write-only |
124 | |"w+" |  Read-write, creates new file if file doesn't exist|
125 | |"a"  |  Write-only, appends data at the end of file if file exists else creates a new file|
126 | |"a+" |  Read-write,  read data from beginning but appends data at the end of file if file exists else creates a new file|
127 | 
128 | ### Closing a file
129 | 
130 | ```c
131 | close fileName
132 | ```
133 | ### Writing to a file
134 | 
135 | ```c
136 | puts $filename "data to write to the file"
137 | ```


--------------------------------------------------------------------------------
/underscore.md:
--------------------------------------------------------------------------------
  1 | ---
  2 | title: underscore (Javascript Library)
  3 | description: Underscore is a javascript library which supports function helpers like(map, reduce, filter, pick, each...) without extending any built-in objects.
  4 | created: 2019-11-07
  5 | updated: 2019-10-07
  6 | ---
  7 | 
  8 | Underscore is a javascript library which supports function helpers like(map, reduce, filter, pick, each...) without extending any built-in objects.
  9 | 
 10 | ## Installation
 11 | 
 12 | 1. Using NPM:
 13 | 
 14 | ```sh
 15 | npm install underscore
 16 | ```
 17 | 
 18 | ## Object functions
 19 | 
 20 | ### pick `_.pick(object, keys)`
 21 | 
 22 | ``` javascript
 23 | const obj = {id: 1, post: "foo", userId: "bar", "created": "2019-10-19"}
 24 | _.pick(obj, userId, post, created);   // returns filtered object with selected keys
 25 | // prints { userId: "bar", post: "foo",  "created": "2019-10-19"}
 26 | ```
 27 | 
 28 | ### extend `_.extend(object, newObject)`
 29 | 
 30 | ```javascript
 31 | const obj = {id: 1, post: "foo", userId: "bar", "created": "2019-10-19"}
 32 | _.extend(obj, {updated: "2019-10-19"})  // returns a object with updated key in it
 33 | // prints  {id: 1, post: "foo", userId: "bar", "created": "2019-10-19", updated: "2019-10-19"}
 34 | ```
 35 | 
 36 | ### invert `_.invert(object)`
 37 | 
 38 | ``` javascript
 39 | const obj = {1: id, "foo": "post", "foo": "userId"}
 40 | _.invert(obj);   // makes keys as values and values as keys
 41 | // prints {id: 1, post: "foo", userId: "bar"}
 42 | ```
 43 | ### omit `_.omit(object, key)`
 44 | 
 45 | ``` javascript
 46 | const obj = {id: 1, post: "foo", userId: "bar", "created": "2019-10-19", updated: "2019-10-19"}
 47 | _.omit(obj, updated)  // removes the specified key from the object
 48 | // prints {id: 1, post: "foo", userId: "bar", "created": "2019-10-19"}
 49 | ```
 50 | 
 51 | ### clone `_.clone(obj)`
 52 | ``` javascript
 53 | _.clone({post: "foo"}) // prints {{post: "foo}}
 54 | ```
 55 | 
 56 | ### has `_.has(obj, key)`
 57 | 
 58 | ``` javascript
 59 | const obj = {id: 1, post: "foo", userId: "bar", "created": "2019-10-19", updated: "2019-10-19"}
 60 | _.has(obj, userId)  // returns boolean value as per given key
 61 | // prints  true
 62 | 
 63 | ```
 64 | 
 65 | ### isEmpty `_.isEmpty(obj)`
 66 | 
 67 | ``` javascript
 68 | _.isEmpty({id:1}) // returns boolean value
 69 | //prints true
 70 | ```
 71 | ### pairs `_.pairs(object)`
 72 | 
 73 | ``` javascript
 74 | _.pairs({id: 1, post: "foo", userId: "bar"}) // converts object into an array
 75 | // prints [[id, 1],[post, "foo"],[userId, foo]]
 76 | ```
 77 | 
 78 | ### keys `_.keys(object)`
 79 | 
 80 | ``` javascript
 81 | _.keys({name:"foo", age: 25})
 82 | // prints [name, age]
 83 | ```
 84 | ### values `_.values(object)`
 85 | 
 86 | ``` javascript
 87 | _.values({name:"foo", age: 25})
 88 | // prints [foo, 25]
 89 | ```
 90 | 
 91 | ### isObject(object)
 92 | 
 93 | ``` javascript
 94 | _.isObject({}) //  prints true
 95 | ```
 96 | 
 97 | ## Array Functions
 98 | 
 99 | ### first `_.first(array)`
100 | 
101 | ``` javascript
102 | const arr = [1, 2, 3, 4, 5]
103 | _.first(arr);
104 | ```
105 | 
106 | ### indexOf `_.indexOf(array, value)`
107 | 
108 | ``` javascript
109 | const arr = [1, 2, 3, 4, 5]
110 | _.indexOf(arr, 2)  // Returns the index of the given value present in the array or returns -1 if value is not there
111 | // prints 1(index of the value 2 in array)
112 | ```
113 | ### lastIndexOf `_.lastIndexOf(array, 2)`
114 | 
115 | ``` javascript
116 | const arr = [1, 2, 3, 4, 2, 5]
117 | _.lastIndexOf(arr, 2) // Returns the index of last occurrence of the given value or returns -1 if value is not there
118 | // prints 4
119 | ```
120 | 
121 | ### object `_.object(list, values)`
122 | 
123 | ``` javascript
124 | _.object([name, age, phone], ["foo", 25, "0000"])
125 | //prints {name: "foo", age: 25, phone: "0000"}
126 | ```
127 | 
128 | ### range `_.range(startValue, endValue)`
129 | ```javascript
130 | _.range(10)   // Returns the list of integers from startValue
131 | // prints [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
132 | _.range(1, 11)
133 | // prints [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
134 | _.range([])
135 | // prints 0
136 | ```
137 | 
138 | ## Collection Functions
139 | 
140 | ### each `_.each(list, method)`
141 | 
142 | ``` javascript
143 | _.each([1, 2, 3, 4], alert) // display alert for four times
144 | ```
145 | 
146 | ### map `_.map(list, context)`
147 | 
148 | ``` javascript
149 | _.map([2, 4, 6], (num) => {num*3})
150 | // prints [6, 12, 18]
151 | ```
152 | 
153 | ### filter   
154 | 
155 | ``` javascript
156 | _.filter([2, 3, 4, 6, 8], (num) => {num % 2 == 0})
157 | // prints [2, 4, 6, 8]
158 | ```
159 | 
160 | ### find  
161 | 
162 | ``` javascript
163 | _.find([4, 6, 7, 8, 11], (num) => {isPrime})
164 | // prints 7 because it prints first occurrence that passes
165 | ```
166 | 
167 | ### reject  
168 | 
169 | ``` javascript
170 | var odds = _.reject([1, 2, 3, 4, 5, 6], (num)=> { num % 2 == 0 })
171 | // prints [1, 3, 5]
172 | ```
173 | 
174 | 


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/vuejs.md:
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  1 | ---
  2 | title: VueJS
  3 | description: The Progressive JavaScript Framework. An approachable, performant and versatile framework for building web user interfaces.
  4 | created: 2022-10-01
  5 | updated: 2012-10-01
  6 | ---
  7 | 
  8 | ### Installation
  9 | > Requires NPM/ Yarn for using without CDN
 10 | 
 11 | |Command|Description|
 12 | |---|---|
 13 | |`npm install -g @vue/cli`|Install VueJS through NPM|
 14 | |`yarn global add @vue/cli`|Install VueJS through Yarn|
 15 | 
 16 | ### Creating A Project
 17 | 
 18 | |Command|Description|
 19 | |---|---|
 20 | |`vue create <project-name>`|Creates and initializes the project with chosen features|
 21 | |`vue ui`|Opens a GUI in the browser. Recommended if not comfortable with CLI|
 22 | 
 23 | ### Vue Template Syntax
 24 | > The Vue app is broken into 3 main components
 25 | 
 26 | ##### Template/ HTML
 27 | ```html
 28 | <template>
 29 |     HTML goes Here
 30 | </template>
 31 | ```
 32 | ##### Javascript
 33 | ```html
 34 | <script>
 35 |     Javascript related things and Vue APIs
 36 | </script>
 37 | ```
 38 | ##### Styling
 39 | ```html
 40 | <style>
 41 |     CSS goes here
 42 | </style>
 43 | ```
 44 | > Basic Example
 45 | 
 46 | ```html
 47 | <template>
 48 |   <h1 id="heading">{{ message }}</h1>
 49 | </template>
 50 | 
 51 | <script>
 52 | export default {
 53 |   data() {
 54 |     return {
 55 |       message: 'Hello World!'
 56 |     }
 57 |   }
 58 | }
 59 | </script>
 60 | 
 61 | <style>
 62 |     #heading {
 63 |         color: pink;
 64 |     }
 65 | </style>
 66 | ```
 67 | 
 68 | ### Vue Directives 
 69 | |Directive|Functionality|
 70 | |---|---|
 71 | |`v-if`|Puts el in DOM if true|
 72 | |`v-else-if`|Usual else if condition check|
 73 | |`v-else`|Usual condition if nothing holds true|
 74 | |`v-show`|Toggles display CSS value|
 75 | |`v-html`|Sets innerHTML|
 76 | |`v-for`|Loop through an array or object|
 77 | |`v-model`|Two way data binding|
 78 | |`v-bind or :`|Reactively updates an attribute|
 79 | |`v-on or @`|Listen to DOM events|
 80 | 
 81 | > Basic Example
 82 | 
 83 | ```html
 84 | <template>
 85 |     <!-- Conditionals & Event Listening -->
 86 |   <h1 v-if="awesome">Vue is awesome! {{ message }}</h1>
 87 |   <h1 v-else>Oh no 😢</h1>
 88 |   <button v-on:click="awesome = !awesome">Toggle</button>
 89 |   
 90 |   <!-- Looping -->
 91 |   <li v-for="item in items" :key="item">
 92 |     <span>{{ item }}</span>
 93 |   </li>
 94 | </template>
 95 | 
 96 | <script>
 97 | export default {
 98 |   data() {
 99 |     return {
100 |       message: 'Hello World!',
101 |       awesome: false,
102 |       items: [1, 2, 3],
103 |     }
104 |   }
105 | }
106 | </script>
107 | 
108 | <style>
109 | </style>
110 | ```
111 | 
112 | ### Vue Lifecycle Hooks
113 | |Hook|Description|
114 | |---|---|
115 | |`beforeCreate()`|The beforeCreate hook runs at the initialization of your component - data has not been made reactive, and events have not been set up yet.|
116 | |`created()`|The created hook runs before the templates and Virtual DOM have been mounted or rendered.|
117 | |`beforeMount()`|The beforeMount hook runs right before the initial render happens and after the template or render functions have been compiled.|
118 | |`mounted()`|In the mounted hook, you will have full access to the reactive component, templates, and rendered DOM (via this.$el).|
119 | |`beforeUpdate()`|The beforeUpdate hook runs after data changes on your component and the update cycle begins, right before the DOM is patched and re-rendered.|
120 | |`updated()`|The updated hook runs after data changes on your component and the DOM re-renders.|
121 | 
122 | > For detailed info visit this [article](https://www.digitalocean.com/community/tutorials/vuejs-component-lifecycle).
123 | 
124 | 
125 | ### Vue Object APIs
126 | |API|Description|
127 | |---|---|
128 | |`data()`|Initializes the reactive data.|
129 | |`props`|Data visible by Parent.|
130 | |`components`|Registers children.|
131 | |`methods`|Set of Vue methods.|
132 | |`computed`|Similar to methods but these are reactive & cached.|
133 | |`watchers`|Watches for a value change.|
134 | 
135 | 
136 | ### Some Top Libraries\Frameworks Used With VueJS
137 | |Name|Description|
138 | |---|---|
139 | |`vuex`|State Management|
140 | |`vue-router`|Handles routing for SPAs|
141 | |`vuetify`|Material Design component framework.|
142 | |`axios`|Promise based HTTP client for the browser and node.js|
143 | 
144 | 
145 | 


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/vyper.md:
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  1 | ---
  2 | title: Vyper
  3 | description: Vyper is a contract-oriented, pythonic programming language that targets the Ethereum Virtual Machine (EVM).
  4 | created: 2022-10-04
  5 | updated: 2022-10-04
  6 | ---
  7 | 
  8 | ## Types
  9 | 
 10 | ### Integer
 11 | 
 12 | Unsigned : `uint256`
 13 | 
 14 | Signed : `int128`
 15 | 
 16 | #### Operators 
 17 | 
 18 | - *Comparison*: `<, >, <=, >=, ==, !=`
 19 | - *Arithmetic*: `+, -, unary -, *, /, **, %, min(), max()`
 20 | - *Bitwise*: `bitwise_and(), bitwise_not(), bitwise_or(), bitwise_xor(), shift()`
 21 | 
 22 | > In `shift(a, _shift)` _shift must be of the type int128, where positive _shift means a left shift and negative _shift means a right shift.
 23 | 
 24 | ### Decimels
 25 | 
 26 | `decimal`: Holds a decimal fixed point value.
 27 | 
 28 | #### Operators 
 29 | 
 30 | - *Comparison*: `<, >, <=, >=, ==, !=`
 31 | - *Arithmetic*: `+, -, unary -, *, /, **, %`
 32 | 
 33 | 
 34 | ### Address
 35 | 
 36 | `address`: Holds an Ethereum address (20 byte value).
 37 | 
 38 | #### Members
 39 | 
 40 | - `balance`: Get balance of the address in `wei_value`.
 41 | - `codesize`: Get code stored at this address. Returns `int128`.
 42 | 
 43 | 
 44 | ### Time
 45 | 
 46 | `timestamp`: Holds the time
 47 | 
 48 | `timedelta`: Time difference
 49 | 
 50 | > Two `timedelta` or a `timedelta` and a `timestamp` can be added together . It is not possible to add two `timestamp` values.
 51 | ### wei_value
 52 | 
 53 | `wei_value`: Holds amount of Ether in its smallest denomination.
 54 | 
 55 | ### Boolean
 56 | 
 57 | `bool`: true or false
 58 | 
 59 | **Operators**: not, and, or, ==, !=
 60 | 
 61 | 
 62 | ### Structs
 63 | 
 64 | User defined data type.
 65 | 
 66 | ```python
 67 | <struct_name>: {
 68 |     <value>: <data_type>,
 69 |     <value>: <data_type>,
 70 |     ...
 71 | }
 72 | ```
 73 | 
 74 | ### Mappings
 75 | 
 76 | Mappings are similar to hash tables.
 77 | 
 78 | ```python
 79 | <mapping_name>: <value_type>[<key_type>]
 80 | ```
 81 | 
 82 | ## Functions
 83 | 
 84 | ### Structure
 85 | 
 86 | ```
 87 | def <function_name>(<param_name>: <param_type>, ...) -> <return_type>:
 88 |     <definition>
 89 |     ...
 90 | ```
 91 | 
 92 | ### Constructor
 93 | 
 94 | Function which is called during contract creation
 95 | 
 96 | ```python
 97 | def __init__(_a: address, _b: bool):
 98 |   self.a = _a;
 99 |   self.b = _b
100 | ```
101 | 


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/wc.md:
--------------------------------------------------------------------------------
 1 | ---
 2 | title: wc Linux Command
 3 | description: wc (word count) Linux Command is used to read standurd input or a list of files and generates new lines count  or word count or byte count.
 4 | created: 2019-09-13
 5 | updated: 2019-09-13
 6 | ---
 7 | 
 8 | wc (word count) Linux Command is used to read standurd input or a list of files and generates new lines count  or word count or byte count.
 9 | 
10 | 
11 | ## Syntax
12 | 
13 | ```sh
14 | wc [Option(s)] [file(s)]
15 | ```
16 | 
17 | 
18 | ## Options
19 | 
20 | |Option| Description|
21 | |---|---|
22 | |-l| prints lines count|
23 | |-c|prints byte count|
24 | |-m|prints character count|
25 | |-L|prints length of longest line|
26 | |-w|prints word count|
27 | 
28 | ## Examples
29 | 
30 | Lets take a file `readme.txt` with following content 
31 | 
32 | ```sh
33 | $ cat readme.txt
34 | Hello World line-1
35 | Hello World line-2
36 | Hello World line-3
37 | Hello World line-4
38 | Hello World line-5
39 | Hello World line-6
40 | Hello World line-7
41 | Hello World line-8
42 | Hello World line-9
43 | Hello World line-10
44 | ```
45 | 
46 | #### Print lines count of a file
47 | ```sh
48 | wc -l readme.txt #=>  10 readme.txt
49 | ```
50 | 
51 | #### Print words count of a file
52 | 
53 | ```sh
54 | wc -w readme.txt #=> 30 readme.txt
55 | ```
56 | 
57 | #### Print character count of a file
58 | ```sh
59 | wc -c readme.txt #=> 191 readme.txt
60 | ```


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/windows-shortcuts.md:
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 1 | ---
 2 | title: Windows Shortcuts
 3 | description: List of Windows keyboard shortcuts.
 4 | created: 2022-10-27
 5 | updated: 2022-10-27
 6 | ---
 7 | 
 8 | ## Basic Shortcuts
 9 | 
10 | | Command | Description |
11 | | ------- | ----------- |
12 | | `F1` | Display Help |
13 | | `Ctrl + X` | Cut the selected item |
14 | | `Ctrl + C` | Copy the selected item |
15 | | `Ctrl + V` | Paste the selected item |
16 | | `Ctrl + Z` | Undo an action |
17 | | `Ctrl + Y` | Redo an action |
18 | | `Ctrl + A` | Select All |
19 | | `Ctrl + F` | Find |
20 | | `Ctrl + P` | Print |
21 | | `Ctrl + S` | Save |
22 | | `Ctrl + T` | Open New Tab |
23 | | `Ctrl + O` | Open |
24 | | `Ctrl` + `+` | To increase the size |
25 | | `Ctrl` + `-` | To decrease the size |
26 | |` Ctrl + D`| Delete the selected item and move it to the Recycle Bin |
27 | |` Ctrl + E`| Open Search (in most apps) |
28 | |` Ctrl + R`| Refresh the active window |
29 | |` Ctrl + Right arrow`| Move the cursor to the beginning of the next word |
30 | |` Ctrl + Left arrow`| Move the cursor to the beginning of the previous word |
31 | |` Ctrl + Down arrow `| Move the cursor to the beginning of the next paragraph |
32 | |` Ctrl + up arrow`| Move the cursor to the beginning of the previous paragraph |
33 | | `Ctrl + Shift + Esc` | Open Task Manager |
34 | | `Alt + F4` | Close the current program window |
35 | | `Alt + Tab` | Switch between open windows by holding Alt and using tab to change |
36 | | `Alt + Esc` | Switches between open windows in the order that they were first opened |
37 | 
38 | ## Windows Keys Shortcuts
39 | 
40 | | Command | Description |
41 | | ------- | ----------- |
42 | | `Win` | Display or hide the Start screen |
43 | | `Win + ,` | See your desktop until you hold keys |
44 | |` Win + D`| Display and hide the desktop |
45 | | `Win + E` | Open File Explorer |
46 | |` Win + L`| Lock your PC |
47 | | `Win + V` | Open clipboard |
48 | |` Win + X`| Open the Quick Link menu |
49 | |` Win + Tab`| Open task view |
50 | |` Win + M`| Minimize all windows |
51 | |` Win + R`| Open the Run dialog box |
52 | |` Win + A`| Open the Action Center |
53 | | `Win + I` | Open settings |
54 | |` Win + C`| Launch Cortona in listening mode (used for voice commands) |
55 | |` Win + S`| Search/Launch Cortona (listening mode) |
56 | | `Win + .` | Use emoji in any App |
57 | |` Win + Ctrl + D`| Create New Virtual Desktop |
58 | |` Win + Ctrl + F4`| Close the Current Desktop |
59 | | `Win + Ctrl + Left Arrow Key` <br /> `Win + Ctrl + Right Arrow Key` | Switch between Virtual Desktops |
60 | | `Win + Left Arrow Key` <br /> `Win + Right Arrow Key` | Snap Current Windows to left or right |
61 | |` Win + PrtScn` <br/> ` Fn + Win + Spacebar`| For taking screenshot |
62 | |` Win + Shift + S`| Open Windows Snipping Tool |
63 | |` Win + Upper Arrow key`| Maximize windows |
64 | | `Win + number key` | To open application from taskbar with numbered key position |
65 | 
66 | ## File Explorer Shortcuts
67 | 
68 | | Command | Description |
69 | |---------|------------|
70 | | `Ctrl + W` | Close the current window |
71 | | `Shift + Tab`| Set Focus on Side Bar |
72 | | `Ctrl + N`| Duplicate the File Explorer |
73 | | `Crtl + Shift + N`| Create a New Folder |
74 | | `Alt + ←`| Navigate to previous folder |
75 | | `Ctrl + L` | Navigate to the address bar |
76 | | `F2` | Rename any file or folder |
77 | 


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/yaml.md:
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 1 | ---
 2 | title: YAML (YAML Ain't Markup Language)
 3 | description: YAML is a human-friendly data serialization language. This is the most commonly used sytax for configuration files.
 4 | created: 2019-06-20
 5 | updated: 2019-06-20
 6 | color: #e74c3c
 7 | ---
 8 | 
 9 | YAML is a human-friendly data serialization language. This is the most commonly used sytax for configuration files.
10 | 
11 | 
12 | ## Example YAML file
13 | ```yaml
14 | ---
15 | title: Post Title
16 | descrription: Post description
17 | content: Post Content...........
18 | tags:
19 | - tag1
20 | - tag2
21 | - tag3
22 | user:
23 |   id: 1
24 |   name: user name
25 |   address:
26 |     streetAddress: foo
27 |     zip: '01234'
28 | ...    
29 | ```
30 | 
31 | ## Rules
32 | 1. content starts with `---` & ends witth `...` (This is an optional rule)
33 | 2. Key value pairs are separated by colon & space( `: ` )
34 | 3. List values start with hyphen & space ( `- ` )
35 | 


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