├── Readme.md
├── Shortcuts.md
├── TerminalCommands.md
└── penguin.gif


/Readme.md:
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 1 | # Linux Commands CheatSheet
 2 | Namaste Developers (* ^_^ *)
 3 | <br/>
 4 | Here I present Linux Commands CheatSheet to you(👉ﾟヮﾟ)👉
 5 | 
 6 | ---
 7 | 
 8 | - Make sure to ⭐ the repository for a quick glance when you want to refer to it.
 9 | - Any contributions to this repo are welcome🐧
10 | 
11 | 
12 | <img src="penguin.gif" style="width:300px; height:300px; border-radius:5%;">


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/Shortcuts.md:
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 1 | ## Shortcuts known:
 2 | 
 3 | - To open a terminal: `CTRL + ALT + T` / `Command + Option + T`
 4 | - To minimize all windows opened and vice versa: `CTRL + ALT + D` / `Command + Option + D`
 5 | - To erase everything from the current cursor position to the beginning of the line: `CTRL + U` / `Command + U`
 6 | - To move the cursor to the beginning of the line: `CTRL + A`
 7 | - To move the cursor to the end of the line: `CTRL + E`
 8 | - To clear the terminal: `CTRL + L`
 9 | - To stop the terminal from infinite loop: `CTRL + C` or `CTRL + Z`(suspends the process)
10 | - To exit a program in terminal: `CTRL + D`
11 | - To switch window of same program: `ALT + F6`
12 | - To backspace: `CTRL + H`
13 | - To delete the word before cursor: `CTRL + W`
14 | - To auto-complete files, directories, etc: `Tab`
15 | 


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/TerminalCommands.md:
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  1 | ## Commands known:
  2 | - To see what's in the file(first to last): [`cat <location/filename>`](https://www.geeksforgeeks.org/cat-command-in-linux-with-examples/)
  3 | - To look at a file backwards, starting with the last line: `tac <location/filename>`
  4 | - To show the first 10 lines(default) of a file: [`head <location/filename>`](https://linuxize.com/post/linux-head-command/#head-command-syntax)
  5 | - To show the first 'n' lines of a file: `head -n <location/filename>`
  6 | - To show the last 10 lines(default) of a file: [`tail <location/filename>`](https://linuxize.com/post/linux-head-command/#head-command-syntax)
  7 | - To show the last 'n' lines of a file: `tail -n <location/filename>`
  8 | - To view documentation: [`man <program name or command like python>`](https://www.geeksforgeeks.org/man-command-in-linux-with-examples/)
  9 | - To gain root/administrative access(prompts for password): `sudo`  
 10 | - To stop the graphical interface: `sudo systemctl stop gdm (or sudo telinit 3)`
 11 | - To start the graphical interface: `sudo systemctl start gdm (or sudo telinit 5)`
 12 | - To halt the system(requires superuser access): `shutdown -h`
 13 | - To reboot the system(requires superuser access): `shutdown -r`
 14 | - When administering a multi-user system, we have the option of notifying all users prior to shutdown:
 15 | `sudo shutdown -h <time> "Message"`
 16 | - To find the address of an installed program: `which <app>` or `whereis <app>`
 17 | - To display the print working directory: `pwd`
 18 | - To change the directory to home directory from the current working directory(current working directory replaces terminal's home directory in history): `cd` or `cd ~`
 19 | - To go to parent directory of the current working directory: `cd ..`
 20 | - To go back to previous directory: `cd -`
 21 | - To list all the contents of working directory: `ls`
 22 | - To list all the contents including hidden files of working directory: `ls -a`
 23 | - To get the tree view of the filesystem(`sudo apt install tree` for first time): `tree`
 24 | - To get the tree view of only directories not files: `tree -d`
 25 | - `cd` command remembers the moving history, to see the history: `dirs`
 26 | - To push a directory in history for easy use: `pushd </foldername>`
 27 | - To delete the directory added recently from history: `popd` 
 28 | - To create an empty file: `touch <filename>`
 29 | - To display and redirect ouput of a command: [`tee`](https://linuxize.com/post/linux-tee-command/)
 30 | - To create a new file from the terminal: `touch filename.extension`
 31 | - To create a new file with specific date(time: 24-hour format; LowerLimit of year: 1901):
 32 |     - In string format: `touch -d "YYYY-MM-DD hh:mm:ss" filename.extension`
 33 |     - In Integer-ish format: `touch -t YYYYMMDDhhmm.ss filename.extension`
 34 |     
 35 | >    *For example:<br/>
 36 | touch -d "2010-01-02 00:01:00" xyz.txt<br/>
 37 | touch -t 201001020001.00 xyz.txt<br/>
 38 | Both the above commands create a text file "xyz.txt" with creation date as 02-January-2010 at 12:01 a.m.*
 39 | 
 40 | - To create a directory/folder: `mkdir folderName` or `mkdir location/foldername`
 41 | - To remove an empty directory: `rmdir folderName`
 42 | - To remove a directory along with its contents: `rm -rf folderName`
 43 | - To rename a file/directory: `mv FileName newFileName`
 44 | - To remove a file: `rm fileName`
 45 | - To forcefully remove a file: `rm –f`
 46 | - To interactively remove a file(it asks if you're sure to delete or not): `rm -i`
 47 | - To locate a file: `locate filename`
 48 | 
 49 | - To list all files in the current directory and all of its subdirectories: `find`
 50 | - To search for files and directories in a folder: `find /folder -name filename`
 51 | - To search only for directories: `find /folderName -type d -name somethingToBeFound`
 52 | - To search only for regular files: `find /folderName -type f -name somethingToBeFound`
 53 |     - Commonly used options to shorten the list include:
 54 |         - -name (only list files with a certain pattern in their name)
 55 |         - -iname (also ignore the case of file names)
 56 |         - -type (which will restrict the results to files of a certain specified type, such as d for directory, l for symbolic link, or f for a regular file, etc.)
 57 | - To kill a process(you can only kill your own processes; those belonging to another user are off limits, unless you are root): `kill -SIGKILL <pid>` or `kill -9 <pid>.` 
 58 | - To see the processes running: `ps -aux` or `htop`
 59 | - To get task manager-ish view of processes running: `top`
 60 | - To see the processes in tree-view: `pstree`
 61 | - To display all jobs running in background(shows the job ID, state, and command name): `jobs`
 62 | - To display all jobs running in background(adds the PID of the background jobs to normal jobs commands): `jobs -l`
 63 | - To display information about mounted filesystems, including the filesystem type, and usage statistics about currently used and available space: `df -Th`
 64 | - To compare two text files(for binary: replace with `cmp`): `diff [options] <file1> <file2>`
 65 |     > Options
 66 |     - `-c` : Provides a list of differences with 3 lines of context
 67 |     - `-r` : Used to recursively compare subdirectories along with present directory
 68 |     - `-i` : To ignore the case of letters
 69 |     - `-w` : To ignore white spaces and tabs
 70 |     - `-q` : To return only if files are different without listing differences 
 71 | - To compare three text files with one as reference: `diff3 <file1> <common-reference-file> <file3>`
 72 | - To get the extension of a file: `file <fileName>`
 73 | - To sync files between hosts: [`rsync`](https://www.geeksforgeeks.org/rsync-command-in-linux-with-examples/)
 74 | - Two Ways to add lines to text:
 75 |     - To add a line to a text file: `echo message>filename`
 76 |     - To append the line to text file: `echo message2>>filename`
 77 |         - Example(both ways do the same thing):
 78 |             - echo message 1 > myfile<br/>echo message 2 >> myfile<br/>echo message 3 >> myfile
 79 |             - cat << EOF > myfile<br/>> message 1</br>> message 2<br/>> message 3<br/>> EOF
 80 |             > Above both codes do the same:<br/>
 81 |             message 1<br/>message 2<br/>message 3 
 82 | - To get tutorial about vim (Vi IMproved): `vimtutor`
 83 |     - Commands in vim editor:
 84 |         - Start the editor and edit file: `vi filename`
 85 |         - Start and edit file in recovery mode(recover file after a crash): `vi -r filename`
 86 |         - Read in file and insert at current position: `:r fileName`
 87 |         - Write to the file: `:w`
 88 |         - Write out to file: `:w file`
 89 |         - To overwrite file: `:w! file`
 90 |         - To exit and write out modified file: `:x` or `:wq`
 91 |         - To quit: `:q`	
 92 |         - To quit without saving: `:q!`	
 93 |         - To count the words in a file in vim editor: `:! wc %`
 94 |         - To go from vim terminal to vim editor: press `i`
 95 | - To identify current user: `whoami`
 96 | - To identify all logged-on user: `who`
 97 | - To retrieve currently defined aliases: `alias`
 98 | - To define a new user: `sudo useradd <username>`
 99 | - To delete a user: `sudo userdel <username>`
100 | - To temporary become a super-user: `su`
101 | - To view the files present in the current directory in the long listing format: `ls -l`
102 | - When working with compressed files, most associated utilities required to work have 'z' prefixed to their name:
103 |     - To view a compressed file: `zcat compress_file`
104 |     - To page through a compressed file(it's a filter): `zless compressed-file` or `zmore compressed-file`
105 |     - To search inside a compressed file(-i ignores the case): `zgrep -i "whatever-you-want-to-search" compressed-file`
106 |     - To compare two compressed files: zdiff file1 file2
107 | - To sort the lines, according to the characters at the beginning of each line: `sort <filename>`
108 | - To combine the two files and sort the lines, then display the output to the terminal: `cat file1 file2 | sort`
109 | - To sort the lines in reverse order: `sort -r <filename>`
110 | - To sort the lines by the 3rd field on each line instead of the beginning: `sort -k 3 <filename>`
111 | - To sort the list with removed duplicates, only uniques: `sort -u <filename>`
112 | - To remove duplicate entries from multiple files at once: `sort file1 file2 | uniq > file3` or sort -u file1 file2 > file3
113 | - To count the number of duplicate entries: `uniq -c filename`
114 | - To paste contents from two files in a table format(first line of first file will correspond to first line of second file in a row): `paste file1 file2`
115 | - To paste contents from two files with a delimiter like dash(-)or colon(:)(For example: xyz-123, in this xyz is from first and 123 is from second): `paste -d "delimiter" file1 file2`
116 | - If two files have a common column and you want to merge them in a single file: `join file1 file2`
117 | - To split a text file into equal files of n lines(the 100 newfile names will be suffixed with xx which aa..ab..ac): `split -n "number of files to be splitted in" <file_that_needs_to_be_split> <newfile>`
118 | - Regex(REGular EXpression; used for searching a particular pattern):
119 |     - Match any single character: `.`
120 |     - Match a or z: `a|z`
121 |     - Match end of a line: `$`
122 |     - Match beginning of a line: `^`
123 |     - Match a preceding item 0 or more times: `*`
124 | - To search for a pattern in a file and print all matching lines: `grep [pattern] <filename>`
125 | - To print lines that exclude a certain pattern: `grep -v [pattern] <filename>`
126 | - TO print the lines that contain the numbers 0 through 9: `grep [0-9] <filename>`
127 | - To print context of lines (specified number of lines above and below the pattern) for matching the pattern. Here, the number of lines is specified as n: `grep -C n [pattern] <filename>`
128 | - To convert lower case to upper case(tr stands for translate): `cat filename | tr a-z A-Z`
129 | - To display the number of lines: `wc -l filename` 
130 | - To display the number of bytes: `wc -c filename`
131 | - To display the number of words: `wc -w filename`
132 | - To check the status of the remote host: `ping <hostname>`
133 | - To show current routing table: `route –n` or `ip route`
134 | - To add a static route: `route add -net address` or `ip route add`
135 | - To delete a static route: `route del -net address` or `ip route del`
136 | - To download a web-page: `wget <url>`
137 | - To read a web-page from terminal: `curl <url>`
138 | - To get the contents of a web page and store it to a file: `curl -o filename_to_be_saved url`
139 | - To copy a local file to a remote system in the command prompt: `scp <localfile> <user@remotesystem>:/home/user/`
140 | - To make a shell script for easy automation, you need a .sh file
141 | - Functions in a script file: `function(){ echo "This is a sample function"}`
142 | - Syntax for if-else:<br /> 
143 |     if [condition file]; <br />
144 |     then<br />
145 |     &emsp; statements<br />
146 |     else<br />
147 |     &emsp;    statements<br />
148 |     fi<br />
149 | - Conditions for if:
150 |     - Checks if the file exists: `-e`
151 |     - Checks if the file is a directory: `-d`
152 |     - Checks if the file is a regular file (i.e. not a symbolic link, device node, directory, etc.) : `-f`
153 |     - Checks if the file is of non-zero size: `-s`
154 |     - Checks if the file has [sgid](https://www.geeksforgeeks.org/finding-files-with-suid-and-sgid-permissions-in-linux/) set: `-g`
155 |     - Checks if the file has suid set: `-u`
156 |     - Checks if the file is readable: `-r`
157 |     - Checks if the file is writable: `-w`
158 |     - Checks if the file is executable: `-x`
159 | - Logical operators to be used with if[expression1 -operation expression2]:
160 |     - Equal to: `-eq`
161 |     - Not equal: `-ne
162 | 	- Greater than: `-gt`
163 | 	- Less than: `-lt`
164 | 	- Greater than or equal to: `-ge`
165 | 	- Less than or equal to: `-le`
166 |     - Compares the sorting order of string1 and string2: `[[ string1 > string2 ]]`
167 |     - Compares the characters in string1 with the characters in string2: `[[ string1 == string2 ]]`
168 |     - Saves the length of string1 in the variable myLen1: `myLen1=${#string1}`
169 | - Switch statement:<br />
170 | case expression in<br />
171 |    &emsp;pattern1)&emsp;execute commands ;;<br />
172 |    &emsp;pattern2)&emsp;execute commands ;;<br />
173 |    &emsp;pattern3)&emsp;execute commands ;;<br />
174 |    &emsp;pattern4)&emsp;execute commands ;;<br />
175 |    &emsp;*&ensp;)&emsp;execute some default commands or nothing ;;<br />
176 | esac
177 | - Three types of loops are often used in most programming languages:
178 |     - `for` loop:<br />
179 |         for variable-name in list<br />
180 |         do<br />
181 |         &emsp;execute one iteration for each item in the list until the list is finished<br />
182 |         done
183 |     - `while` loop:<br />
184 |         while condition is true<br />
185 |         do<br />
186 |         &emsp;Commands for execution<br />
187 |         done
188 |     - `until` loop; it repeats a set of statements as long as the control command is false:<br />
189 |         until condition is false<br />
190 |         do<br />
191 |         &emsp;Commands for execution<br />
192 |         done
193 | - To edit/debug a script(to exit: write `+ exit 0` at the end of file): `script.sh debug`
194 | - To create a temporary file: `TEMP=$(mktemp /tmp/tempfile.XXXXXXXX)`
195 | - To create a temporary directory: `TEMPDIR=$(mktemp -d /tmp/tempdir.XXXXXXXX)`
196 | - To generate a random number: `$RANDOM`
197 | - To get the length of a string: `${#string}` or `expr length $string`
198 | - Printing Operations:
199 |     - To print the file to default printer: `lp <filename>`
200 |     - To print to a specific printer (useful if multiple printers are available): `lp -d printer_id <filename>`
201 |     - To print the output of a program: `program | lp
202 | echo string | lp`
203 |     - To print multiple copies: `lp -n number <filename>`
204 |     - To set the default printer: `lpoptions -d printer`
205 |     - To show the queue status: `lpq -a`
206 |     - To configure printer queues: `lpadmin`
207 |     - To get a list of available printers, along with their status: `lpstat -p -d`
208 |     - To check the status of all connected printers, including job numbers: `lpstat -a`
209 |     - To cancel a print job: `cancel job-id` OR `lprm job-id`
210 |     - To move a print job to new printer: `lpmove job-id newprinter`
211 | -  To convert a text file to two columns (-2) formatted PostScript using the command(enscript is a tool that is used to convert a text file to PostScript and other formats): `enscript -2 -r -p psfile.ps textfile.txt`
212 | - To convert a text file to PostScript (saved to psfile.ps): `enscript -p psfile.ps textfile.txt`
213 | - To convert a text file to n columns where n=1-9 (saved in psfile.ps): `enscript -n -p psfile.ps textfile.txt`
214 | - To print a text file directly to the default printer: `enscript textfile.txt`
215 | - To convert a pdf to post-script: `pdf2ps file.pdf` or `pdftops original.pdf converted_name.ps` or `convert original.pdf converted_name.ps`
216 | - To convert a post-script to pdf: `ps2pdf file.ps` or `pstopdf original.ps converted_name.pdf` or `convert original.ps converted_name.pdf`
217 | - To merge the two documents first.pdf and second.pdf to output.pdf: `qpdf --empty --pages first.pdf second.pdf -- output.pdf` or `pdftk first.pdf second.pdf cat output output.pdf`
218 | - To write only pages 1 and 2 of original.pdf to new.pdf: `qpdf --empty --pages original.pdf 1-2 -- new.pdf` or `pdftk A=original.pdf cat A1-2 output new.pdf`
219 | - To rotate page 1 of original.pdf by 90 degrees clockwise to rotated.pdf: `qpdf --rotate=+90:1 original.pdf rotated.pdf`
220 | - To rotate all pages of original.pdf 90 degrees clockwise and save to rotate-all.pdf: `qpdf --rotate=+90:1-z original.pdf rotated-all.pdf` or `pdftk A=original.pdf cat A1-endright output new.pdf`
221 | - To encrypt with 128 bits public.pdf with the passwd mypw with output as private.pdf: `qpdf --encrypt mypw mypw 128 -- public.pdf private.pdf` or `pdftk public.pdf output private.pdf user_pw PROMPT`
222 | - To decrypt private.pdf with output as file-decrypted.pdf: `qpdf --decrypt --password=mypw private.pdf file-decrypted.pdf`
223 | - To open a pdf(evince is a pdf viewing GUI): `evince xyz.pdf`
224 | - CUPS interface is available at: `http://localhost:631`
225 | 


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