├── Commands.md ├── LICENSE └── README.md /Commands.md: -------------------------------------------------------------------------------- 1 |

Linux/Unix Commands

2 | 3 | ## Linux Commands used day to day 4 | - `acpi`- _to display battery status and other acpi information_ 5 | 6 | - `apt-get` - _helps in handling packages in Linux_ 7 | 8 | - `arch` - _used to print computer architecture_ 9 | 10 | - `bc` - _used for command line calculator_ 11 | 12 | - `cal` -_used to see the calendar of a specific month or a whole year_ 13 | 14 | - `cc` - _it is used to compile C language codes and create executables_ 15 | 16 | - `ccrypt` - _command line tool for encryption and decryption of data_ 17 | 18 | - `man` - _used to give description of any linux command like this_ ```$ man ls``` 19 | 20 | - `info` - _an alternative toobtain uder documentation for a given program is to invoke info instead of man ```$ info ls``` 21 | 22 | - `mv` - _mv command is used to move or rename files_ 23 | 24 | - `pwd` - _shows the present working directory_ 25 | 26 | - `chmod` - _command sets the file permissions flags on a file or folder 27 | 28 | - `lsusb` - _command used to check usb port id 29 | 30 | - `lspci` - _command used to check all detailed information about all PCI buses and devices in the system 31 | 32 | ## Listing Files 33 | - `ls` 34 | - If you want to see the list of files on your UNIX or Linux system, use the `ls` command 35 | - `ls -l` or `ll` 36 | - If you want to organize the files in list 37 | - `ls -lh` 38 | - If you want to arrange the files in list and show their size 39 | 40 | ## Listing Hidden Files and Normal Files 41 | - `ls -al` 42 | - If you want ot see the list of all files with all hidden files in the Current directory system in Linux 43 | - `ls -lha` 44 | - If you want to organize files in list format with their sizes and see hidden files 45 | 46 | - `ls -l` 47 | -Displays long list view with detailed file information including file type, permissions, link count, owner, group, size, date and time 48 | 49 | - `ls -lt` 50 | -Lists all files sorted by date and time with the newest file first. 51 | 52 | - `ls -ltr` 53 | -Lists all files sorted by date and time with the oldest file first. 54 | 55 | - `ls -lh` 56 | -Displays all files in current directory with file sizes in human readable format(eg:1.6K,328M,2.4G) 57 | 58 | - `ls -a` 59 | - If you want to list all files including hidden files that start with "." 60 | 61 | - `ls -la` 62 | - Lists all files,including hidden files,in the current directory with detailed information. 63 | 64 | - `ls -F` 65 | - Displays all files in current directory with their file types. 66 | 67 | ## Creating & Viewing Files 68 | - To create a new file, use the command 69 | 1. `cat > filename` 70 | 2. Add content 71 | 3. Press `ctrl + d` to return to command prompt. 72 | - Files can also be quickly created using 73 | - ```echo "Hello World" > ./fileName.txt``` 74 | - To view a file, use the command `cat filename` 75 | 76 | ## Searching for content in a file/ files in a directory 77 | - To search for a word in a file using terminal,use the command ```grep``` 78 | - For eg., if you want to search for the word GNU in a file named ```GNU.txt```,type ``` grep GNU GNU.txt``` 79 | - This will show all lines which have the word ```GNU``` in that file 80 | - To search over multiple files in a directory, use ```grep``` with ```-r``` flag, like ``` grep -r GNU .```. Here ```-r``` stands for recursive search and ```.``` specifies the search root to be the current directory. 81 | 82 | ## Searching for a file 83 | - `find . -name ".js" -print`: find all files with JS extnesion and print them on screen 84 | - `find . -type d -name "*tmp" -print`: print all directories ending with `tmp` 85 | - `find . -type f -exec ls -l {} \;`: use `ls -l` on all returned values 86 | 87 | ## Exiting the shell 88 | - `exit` (also aliased to `bye` or `quit` in some shell flavors) 89 | 90 | ## Get root access 91 | 1. To log in as a super user use one of the following commands in the terminal. You can actually use this command to log in as any user on the machine, but when left blank it will attempt to log in as root.\ 92 | - `su -` 93 | - `sudo -i` 94 | - These commands will ask you for password. 95 | 2. To jump right into root, run\ 96 | - `sudo su -` 97 | - Since there is no root password made after live install. 98 | 3. To run other commands as root temporarily, use the command\ 99 | - `sudo` *`command`* 100 | - Replace the *command* above with your command. Eg: `sudo apt-get update` 101 | 102 | ## Updating, Installing and Listing packages 103 | The commands for installing and updating applications depend on the version of Linux you are using, specifically whether it's Debian- or RPM-based. 104 | 105 | * Debian Based systems 106 | - Update the list of available packages and their versions, but doen not install or upgrade any packages. use the command ```sudo apt update``` 107 | - Install newer versions of installed packages,use the command ```sudo apt upgrade``` 108 | - Install any required package,use ```sudo apt install 'your package name'```. Example: ```sudo apt install apache2``` 109 | 110 | * RPM-based systems 111 | - Update all or specified packages,use ```sudo yum update```. Example for updating specific package: ```sudo yum update mysql``` 112 | - Lists known and installed packages,use ```sudo yum list``` ```sudo yum list --installed``` 113 | - Install requested package,use ```yum install```. Example: ```sudo yum -y install firefox``` 114 | - On Fedora 22 and later, you can also use 'dnf' in place of 'yum'. dnf stands for dandified yum, and is just an updated version of yum. Syntax is very similar, Examples would be: ```sudo dnf update``` or ```sudo dnf install```. More info on this [here.](https://opensource.com/article/18/8/guide-yum-dnf) 115 | - On openSUSE, use ```zypper install PACKAGE_NAME``` and ```zypper remove PACKAGE_NAME``` to install or remove packages. To add an repo in openSUSE, ```sudo zypper addrepo ```. More info on this [here](https://doc.opensuse.org/documentation/leap/reference/html/book.opensuse.reference/cha.sw_cl.html) 116 | 117 | ## Download YouTube videos on Linux 118 | 119 | For this you need to install an utility called **youtube-dl**, which is a command-line program to download videos from YouTube.com and a few more sites. It requires the Python interpreter, version 2.6, 2.7, or 3.2+, and it is not platform specific. It should work on your Unix box, on Windows or on macOS. It is open source project. You can contribute [here.](https://github.com/ytdl-org/youtube-dl) 120 | 121 | To install it right away for all UNIX users (Linux, macOS, etc.), type: 122 | 123 | sudo curl -L https://yt-dl.org/downloads/latest/youtube-dl -o /usr/local/bin/youtube-dl 124 | sudo chmod a+rx /usr/local/bin/youtube-dl 125 | 126 | If you do not have curl, you can alternatively use a recent wget: 127 | 128 | sudo wget https://yt-dl.org/downloads/latest/youtube-dl -O /usr/local/bin/youtube-dl 129 | sudo chmod a+rx /usr/local/bin/youtube-dl 130 | 131 | It is very simple to use. Following are some example usages: 132 | 133 | ```bash 134 | # simplest example 135 | youtube-dl https://www.youtube.com/watch?v=Zuwa8zlfXSY 136 | 137 | # customize the filename of the output 138 | youtube-dl -o '%(title)s by %(uploader)s.%(ext)s' https://www.youtube.com/watch?v=Zuwa8zlfXSY 139 | 140 | # download from multiple urls 141 | youtube-dl 142 | 143 | # or use a file with list of urls 144 | youtube-dl -a url.txt 145 | 146 | ``` 147 | If you are more interested, there are plenty of other options to be explored from [documentation page.](https://github.com/ytdl-org/youtube-dl) 148 | 149 | ## Monitering the temperature of your system 150 | "lm-sensors" is a set of tools to control and view sensors that may be present on your hardware. Included are several applications that run from the command line: 151 | - sensors: shows the current readings of all sensor chips. 152 | - sensord: daemon to periodically log sensor readings to syslog 153 | - fancontrol: calculates fan speeds from temperatures and sets the corresponding PWM outputs 154 | - pwmconfig: tests the PWM outputs of sensors and configures fancontrol 155 | - and more (see [lm-sensors documentation](https://wiki.archlinux.org/index.php/Lm_sensors) for details)` 156 | 157 | You can use it in the following way, 158 | ``` 159 | ~$ sensors 160 | 161 | k8temp-pci-00c3 162 | Adapter: PCI adapter 163 | Core0 Temp: +59.0°C 164 | Core1 Temp: +58.0°C 165 | Core2 Temp: +60.0°C 166 | Core3 Temp: +55.0°C 167 | 168 | it8718-isa-0228 169 | Adapter: ISA adapter 170 | [...] # shortened 171 | ``` 172 | ###To Free up memory cache and buffer 173 | sync; echo 1 > /proc/sys/vm/drop_caches 174 | sync; echo 2 > /proc/sys/vm/drop_caches 175 | sync; echo 3 > /proc/sys/vm/drop_caches 176 | 177 | ## Shutting down the machine 178 | - `shutdown -h now` 179 | -If you want to Shutdown the system and turn the power off immediately. 180 | - `shutdown -h +10` 181 | -If you want to Shutdown the system after 10 minutes. 182 | - `shutdown -r now` 183 | -If you want to Reboot the system using shutdown command. 184 | 185 | 186 | ## Moving between Directories 187 | - Exploring `cd`(change directory) command 188 | 189 | - `cd [directory_name]` 190 | - If you want to change directory to a particular directory,use this command. Eg: cd Documents 191 | 192 | - `cd dir/subdir/subsubdir` 193 | - If you want to move inside a directory from a directory,use this command. Eg: cd Documents/Hacktoberfest/linuxCommands 194 | 195 | - `cd /` 196 | - If you want to change directory to the root directory. Root directory is the first directory in your file system hierarchy. 197 | 198 | - `cd ~` or `cd` 199 | - If you want to change directory to the home directory.Generally known as $HOME,located at path /home//. 200 | Also, `cd` command can be used to do the same above operation. 201 | 202 | - `cd ..` 203 | - It is used to go one level back directory(i.e to parent directory of current directory). 204 | 205 | - `cd ../..` 206 | - It is used to go two levels back directory(i.e to parent's parent directory of current directory). 207 | 208 | - `cd -` 209 | - It is used to change back to the previous working directory. Eg: If `Documents` is present working directory and `Downloads` is previous working directory, this command takes you back to `Downloads` directory. 210 | 211 | - `cd "dir name"` or `cd dir\ name` 212 | - This command is used to navigate to a directory with white spaces.Instead of using double quotes we can use single quotes then also this command will work.Eg: `cd "linux commands"` or `cd linux\ commands` will move to 'linux commands' directory. 213 | ## Configure to mysql 214 | - 'mysql -u root -p' 215 | - enter the mysql password 216 | 217 | ## Import and Export database using cli 218 | 219 | ### Import 220 | `mysql -u root -p db-name < /path/to/databse/file.sql` 221 | 222 | ### Export 223 | `mysql -u root -p db-name > /path/to/new/database.sql` 224 | 225 | It will ask database password. 226 | 227 | ## Creating and Removing Directories 228 | * `mkdir` command is used for creating directories. 229 | - Creating a directory is pretty straightforward. 230 | `mkdir [dir-name]` 231 | 232 | - Creating a complete directory structure. (Non of the directories should already exist) 233 | `mkdir -p dir1/dir2/dir3` 234 | - Make `mkdir` emmit the details of operation. 235 | `mkdir -v [dir-name]` 236 | 237 | * `rmdir` command is used for removing empty directories. 238 | - Removing a directory is also pretty straightforward. 239 | `rmdir [dir-name]` 240 | 241 | - Make `rmdir` ignore non empty directories. 242 | BY default, the rmdir command throws an error if you try deleting a non-empty directory. However, if you want, you can suppress this behavior of rmdir using the `--ignore-fail-on-non-empty` option. 243 | 244 | `rmdir --ignore-fail-on-non-empty [dir-name]` 245 | - Remove parent directories along with the directory. 246 | `rmdir -p test/test-dir/` 247 | 248 | * `rm -r` command is used for removing non empty directories. 249 | - Removing a non empty directory is also pretty straightforward. 250 | `rm -r [dir-name]` 251 | This will present a prompt for approval to delete each of the files. 252 | 253 | - If you don't want such a prompt, 254 | `rm -rf [dir-name]` 255 | This will not present a prompt for approval to delete each of the files. 256 | 257 | ## Compress files on linux 258 | 259 | The following commands are used to compress files on linux. There are many ways to compress files in linux, the most common is **tar** 260 | 261 | * Compress 262 | - The following commands makes an archive named archive.tar containing file foo and bar present in the current directory. 263 | - ```tar -cf archive.tar foo bar``` 264 | - This command lists all the files in an archive verbosely. 265 | - ```tar -tvf archive.tar``` 266 | - The `tar` utility has many options which can be seen using 267 | - ```tar --help``` 268 | * Decompress 269 | - We will again use the `tar` utility to decompress files. The following command is used to decompress the file named `yourfile.tar.gz`. This command is for the `.gz.` extention. 270 | - ```tar -zxvf yourfile.tar.gz``` 271 | - If the file has the extention `.tar`, this command can be used. 272 | - ```tar -xvf yourfile.tar``` 273 | - The above commands will extract to the current folder, to extract to another folder use the following commands. 274 | - ```tar -C /myfolder -zxvf yourfile.tar.gz``` 275 | - ```tar -C /myfolder -xvf yourfile.tar``` 276 | 277 | ## Creating users on linux 278 | 279 | The following commands are used to create users on linux. One method allows you to create a user at a time while another 280 | allows you to create users in bulk 281 | 282 | * Single User 283 | - The following command creates a new user account without any additional actions 284 | - ```useradd joe``` 285 | - The following command creates a new user account and creates a home directory for that user 286 | based on the contents of /etc/skel 287 | - ```useradd -m joe``` 288 | - This command will create the user with the home directory you specify 289 | - ```useradd -d /path/to/home/dir joe``` 290 | * Multiple Users 291 | - The following command creates users based on a `:` delimited list of values. Each user 292 | is separated by a new line 293 | - The user is defined as follows `username:encrypted-password:uid:gid:home-dir:shell` 294 | - Only the first two fields are required for user creation and the password must be encrypted 295 | using the below command 296 | - ```mkpasswd --method=SHA-512``` 297 | - You can leave the user without a password by placing an `x` in place of the encrypted 298 | password. 299 | - Once you set up your file create your users by typing 300 | - ```newusers the-file``` 301 | 302 | ## Modifying users on linux 303 | - ```usermod -L username``` - If you want to lockout a user 304 | - ```usermod -U username``` - If you need to unlock a users account locked with the above 305 | command 306 | - ```passwd username``` - If you need to change a users password 307 | - ```usermod -d /path/to/dir username``` - If you need to change a users home directory 308 | - ```usermod -s /path/to/shell username``` - If you need to change a users shell 309 | 310 | ## Deleting a user on linux 311 | - `userdel username` - Deletes user 312 | - `userdel -r username` - Deletes user and their home directory and mail spool file 313 | 314 | 315 | ## Basic Commands 316 | 317 | ### `htop` 318 | 319 | - The `htop` command is used get information about the system such as CPU usage, RAM usage, Swap usage etc. It also give information regarding the uptime, average load and currently running tasks. 320 | - To use this utility, simply type `htop` and press enter. 321 | 322 | Syntax: 323 | 324 | ``` 325 | $ htop 326 | ``` 327 | 328 | ### `wget` 329 | 330 | - The `wget` command is one of the simplist commands in linux. It allows the user to fetch internet resources without having to open a browser. 331 | - ***Basic Use:*** 332 | 333 | Syntax: 334 | 335 | ``` 336 | $ wget url 337 | ``` 338 | 339 | Example: 340 | 341 | - Suppose we want to download a cat photo stored on say `https://example.com/cat.png'. To do so, we'll use the following command. 342 | ``` 343 | $ wget https://example.com/cat.png 344 | ``` 345 | - This will download and save the file to the current directory with the name `cat.png`. 346 | 347 | ### `wc` 348 | 349 | - One of the most basic commands, `wc` allows the user to count the number of bytes, characters, words and lines of each given file or standard input and print the result. 350 | 351 | - ***Basic Use:*** 352 | 353 | Syntax: 354 | ```bash 355 | $ wc filename # output: number_of_lines number_of_words number_of_characters /path/to/file 356 | ``` 357 | 358 | Example: 359 | ```bash 360 | $ wc /proc/cpuinfo # output: 208 1232 6336 /proc/cpuinfo 361 | ``` 362 | 363 | ### `touch` 364 | 365 | - `touch` is a simple command that allows the user to create an empty file. Note that with `touch`, you can only create the file and not edit it. 366 | 367 | - ***Basic Use:*** 368 | 369 | Syntax: 370 | ```bash 371 | $ touch filename 372 | $ ls -l filename 373 | -rw-rw-rw- 1 current_user users 0 Oct 9 22:03 filename 374 | ``` 375 | 376 | Example: 377 | Logged in as user ***linux_is_awesome*** 378 | ```bash 379 | $ touch hello 380 | $ ls -l hello 381 | -rw-rw-rw- 1 linux_is_awesome users 0 Oct 9 22:03 hello 382 | ``` 383 | 384 | ### `whoami` 385 | 386 | - `whoami` command displays the username of the current user. 387 | 388 | - ***Basic Use:*** 389 | 390 | Syntax: 391 | ```bash 392 | $ whoami 393 | current_user 394 | ``` 395 | 396 | Example: 397 | Logged in as user ***linux_is_awesome*** 398 | ```bash 399 | $ whoami 400 | linux_is_awesome 401 | ``` 402 | 403 | ### `grep` 404 | - `grep` is an extremely useful command to know in Linux. 405 | - It stands for “global regular expression print". Basically, it's used for pattern matching. `grep` processes text line by line and prints any lines which match a specified pattern. 406 | 407 | - ***Basic Use:*** 408 | Syntax: 409 | ```bash 410 | $ grep [option(s)] pattern [file(s)] 411 | ``` Creating a test file for using `grep`: 412 | ```bash 413 | $ cat > grep_test.txt 414 | This is a test file. AAA, BBB, 123, CaSe ExAmPle. 415 | ``` 416 | 417 | Example: 418 | ```bash 419 | $ grep AAA grep_test.txt 420 | This is a test file. AAA, BBB, 123, CaSe ExAmPle. # AAA will be highlighted in the output 421 | 422 | $ grep -i case grep_test.txt # ignore case while searching 423 | This is a test file. AAA, BBB, 123, CaSe ExAmPle. # CaSe will be highlighted in the output 424 | ``` 425 | ### TO CHECK DISK SPACE USED AND AVAILAVBLE 426 | - COMMANDS 427 | $df (Table that lists for each device name on the system) 428 | $df -h (To see output in Human Readable Format) 429 | $df -m (Output in one-megabyte) 430 | $df -k (Output in one-kilobyte blocks) 431 | 432 | ### TO CHECK DISK SPACE USED BY SPECIFIED FILES AND FOR EACH SUB-DIRECTORY 433 | -COMMANDS 434 | $du (Names and space consumption of each of the directories including all subdirectories) 435 | $du -h (To see output in Human Readable Format) 436 | 437 | To find out /etc/ directory space usage : 438 | $du /etc/ 439 | $du -h /etc/ 440 | 441 | ### `echo` 442 | 443 | - `echo` display a line of text. 444 | 445 | - ***Basic Use:*** 446 | Syntax: 447 | ```bash 448 | $ echo options string 449 | $ echo "hello world" 450 | hello worl 451 | ``` 452 | Example: 453 | ```bash 454 | $ echo $USER 455 | carlan 456 | $ echo $HOME 457 | /home/carlan 458 | $ forename=carlan 459 | $ echo "${forename}" 460 | carlan 461 | $ echo -e "hello\nworld" 462 | hello 463 | world 464 | $ echo '${forename}' 465 | ${forename} 466 | $ echo "This is my home folder ${HOME}" > /tmp/myhomefolder.txt 467 | $ cat /tmp/myhomefolder.txt 468 | This is my home folder /home/carlan 469 | ``` 470 | 471 | 472 | 473 | ### `diff` 474 | - `diff` is an extremely useful command to know in Linux and often used in GIT as well as `git diff`. 475 | - Compare FILES line by line 476 | 477 | - ***Basic Use:*** 478 | Syntax: diff [OPTION]... FILES 479 | ```bash 480 | $ cat > diff_test_file1.txt 481 | This is a test file 1 482 | $ cat > diff_test_file2.txt 483 | This is a test file 2 484 | ``` 485 | Example: 486 | ```bash 487 | $ diff diff_test_file1.txt diff_test_file2.txt 488 | 1c1 489 | < This is a test file 1 490 | --- 491 | > This is a test file 2 492 | ``` 493 | 494 | ### `printf` 495 | 496 | `printf` command in Linux is used to display the given string, number or any other format specifier on the terminal window. 497 | 498 | It's just like echo, but on steroids. 499 | 500 | #### Syntax: 501 | 502 | `printf [-v var] format [arguments]` 503 | 504 | `Printf` can have format specifiers, escape sequences or ordinary characters. 505 | 506 | #### commonly used `printf` specifiers: 507 | 508 | | specifiers | Description | 509 | |------------|-------------| 510 | | `%s` | a string specifier for string output | 511 | | `%d` | an integer specifier for showing the integral values | 512 | 513 | #### Example: 514 | 515 | ```sh 516 | printf "%s" "Hello, World!" 517 | # > Hello, World! 518 | ``` 519 | 520 | ```sh 521 | printf "%d\n" "213" "109" 522 | # > 213 523 | # > 109 524 | ``` 525 | 526 | ### `tee` 527 | ```tee``` command reads the standard input and writes it to both the standard output and one or more files. 528 | 529 | It basically breaks the output of a program so that it can be both displayed and saved in a file, simultaneously 530 | 531 | ### Syntax: 532 | 533 | ```tee [OPTION]... [FILE]...``` 534 | 535 | The most useful option is probably the ```-a``` switch, which appends to the specified files rather than overwriting them. ```tee``` also creates the files if they don't exist. 536 | 537 | ### Example: 538 | 539 | ```bash 540 | printf "Hello World" >> a.txt 541 | # Creates file a.txt (assuming it wasn't there) with content "Hello World" 542 | touch b.txt 543 | #Creates b.txt 544 | wc -w a.txt|tee -a b.txt 545 | # Output: 2 a.txt 546 | cat b.txt 547 | # Output: 2 a.txt 548 | #Run it again 549 | wc -w a.txt|tee -a b.txt 550 | # Output: 2 a.txt 551 | cat b.txt 552 | # Output: 2 a.txt (on 2 lines) 553 | ``` 554 | 555 | **Multiple file example**: 556 | 557 | ```bash 558 | # Follow steps of previous example first 559 | touch c.txt 560 | wc -w a.txt|tee -a b.txt c.txt 561 | # Output: 2 a.txt 562 | cat b.txt 563 | # Output: 2 a.txt (on 3 lines) 564 | cat c.txt 565 | cat b.txt 566 | # Output: 2 a.txt 567 | ``` 568 | ### `ssh` 569 | ```ssh``` command can be used for accessing remote server (remote login program) 570 | 571 | 572 | ### Syntax: 573 | ```ssh username@serverip``` 574 | 575 | This command connects you to a server which has an IP address as `serverip` and username as `username`. 576 | 577 | :fire: For complete info hit `man ssh` in terminal 578 | ______ 579 | 580 | ### `screen` 581 | 582 | ```screen``` -- a full-screen software program that can be used to multiplexes a physical console between several processes (typically interactive shells). It offers a user to open several separate terminal instances inside a one single terminal window manager. 583 | 584 | + Prerequisites 585 | 586 | ```bash 587 | apt-get install screen (On Debian based Systems) 588 | ``` 589 | or 590 | 591 | ```bash 592 | yum install screen (On RedHat based Systems) 593 | ``` 594 | 595 | ### ex: Create a screen 596 | 597 | `$ screen -S [NAME_of_screen]` 598 | 599 | + e.g `screen -S frodo` 600 | 601 | ### ex: Detach a screen (when already inside screen interactive shell) 602 | 603 | `press Ctrl-A and 'D'` 604 | 605 | you will see the output like this: 606 | 607 | `[detached from 711.frodo]` 608 | 609 | ### ex: List of current screen sessions 610 | 611 | `$ screen -ls` 612 | 613 | ```bash 614 | @ubuntu ~ $ screen -ls 615 | There are screens on: 616 | 711.frodo (10/01/2016 01:15:45 AM) (Detached) 617 | 2231.pts-0.ubuntu (06/06/2015 08:12:05 AM) (Detached) 618 | 2 Sockets in /var/run/screen/S-nightz 619 | 620 | ``` 621 | 622 | ### ex: restore screen (e.g 711.frodo) to continue your works 623 | 624 | `$ screen -r 711` 625 | 626 | 627 | ### ex: Kill screen (when already inside screen interactive shell) 628 | 629 | `press Ctrl-A and 'k'` 630 | 631 | then the terminated prompt will be appeared as: 632 | 633 | ```bash 634 | Want to kill this window [Y/N] > 635 | ``` 636 | _________________ 637 | 638 | ### strace 639 | 640 | ```strace``` -- powerful command line tool for debugging and trouble shooting programs in Unix-like operating systems such as Linux. It captures and records all system calls made by a process and the signals received by the process 641 | 642 | - ```strace``` will fill your screen with continues output that shows system calls being made by the process, to end it, press **[Ctrl + C]** 643 | 644 | ### ex: trace Linux Command System Calls 645 | 646 | + e.g: tracing of all system calls made by the **`df`** command 647 | 648 | ```bash 649 | $ strace df -h 650 | 651 | 652 | execve("/bin/df", ["df", "-h"], [/* 50 vars */]) = 0 653 | brk(NULL) = 0x136e000 654 | access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) 655 | mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f82f78fd000 656 | access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory) 657 | open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3 658 | fstat(3, {st_mode=S_IFREG|0644, st_size=147662, ...}) = 0 659 | mmap(NULL, 147662, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f82f78d8000 660 | close(3) = 0 661 | access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) 662 | 663 | ``` 664 | 665 | #### Where: 666 | 667 | + **access** -- one of types of system call 668 | + **("/etc/ld.so.preload", R_OK)** -- system call argument 669 | + **-1 ENOENT** -- system call return value 670 | 671 | ### ex: trace Linux Process PID 672 | 673 | ```bash 674 | $ sudo strace -p [PID] 675 | 676 | example 677 | 678 | $ sudo strace -p 3569 679 | 680 | strace: Process 3569 attached 681 | restart_syscall(<... resuming interrupted poll ...>) = 1 682 | recvmsg(4, {msg_name(0)=NULL, msg_iov(1)=[{"U0!70 683 | 684 | ``` 685 | _________________ 686 | 687 | ## Network 688 | 689 | ### `ifconfig` 690 | 691 | - Used to configure network interface parameters and displays information about all network interfaces currently in operation. 692 | 693 | - `ifconfig -a` 694 | - Print out the configuration of all network interfaces on the system. 695 | 696 | - `ifconfig interface` 697 | - Print out the configuration of a specific interface. 698 | 699 | ### ex: ifconfig interface 700 | ```example 701 | 702 | $ ifconfig eth0 703 | ``` 704 | 705 | - `sudo ifconfig interface up` 706 | - Enable an interface if it is disabled. 707 | 708 | ### ex: Enabling an interface 709 | ``` 710 | example 711 | 712 | $ sudo ifconfig eth0 up 713 | ``` 714 | 715 | - `sudo ifconfig interface down` 716 | - Disable an interface if it is enabled. 717 | 718 | ### ex: Disabling an interface 719 | ``` 720 | example 721 | 722 | $ sudo ifconfig eth0 down 723 | ``` 724 | 725 | ### `ping` 726 | 727 | - It is used to test the connectivity status between a source and destination computer/device over an IP network. 728 | 729 | ### ex: use ping 730 | ```bash 731 | $ ping ip 732 | 733 | example 734 | 735 | $ ping 192.168.1.254 736 | ``` 737 | 738 | ### `whois` 739 | 740 | - whois is a simple tool that allows you to see information about a specific domain name or IP address. You can use it to see things like contact information, nameservers, and domain registration information. 741 | 742 | ### ex: install whois 743 | ``` 744 | $ sudo apt install whois 745 | ``` 746 | 747 | ### ex: use whois 748 | ```bash 749 | $ whois domain 750 | 751 | example 752 | 753 | $ whois www.github.com 754 | ``` 755 | 756 | ### `netstat` 757 | 758 | - Netstat command allows you a simple way to review each of your network connections and open sockets. 759 | 760 | - `netstat -a` 761 | - List out all the current connections 762 | 763 | - `netstat -at` 764 | - List only TCP connections 765 | 766 | - `netstat -au` 767 | - List only UDP connections 768 | 769 | - `netstat -an` 770 | - Disable reverse dns lookup for faster output if you do not need to know the host name and just the ip address. 771 | 772 | - `netstat -s` 773 | - Print out network statistics like total number of packets received and transmitted by protocol type and so on. 774 | 775 | - `netstat -i` 776 | - Print out the information about the network interfaces. 777 | 778 | - `netstat -g` 779 | - Display the multicast group information for IPv4 and IPv6 protocols. 780 | 781 | ### `w` 782 | 783 | - w provides a quick summary of every user logged into a computer, what each user is currently doing, and what load all the activity is imposing on the computer itself. 784 | 785 | ### ex: using w 786 | ``` 787 | example 788 | 789 | $ w 790 | ``` 791 | ### ssh 792 | - SSH stands for secure shell. To login in to a system with user name `user` and `ip-10.85.85.85`,type: 793 | ```ssh user@10.85.85.85``` 794 | - This shall allow you to access the terminal of the remote PC with the user account of ```user``` 795 | 796 | ### ssh-keygen(Generation and Usage) 797 | - Inorder to avoid entering the password to remote servers/applications. 798 | - While ```git push```, we can avoid this scenario by adding a key to our GitHub. 799 | - Steps: 800 | ``` Scenario 1 using the existing key``` 801 | 1. Check for existing keys. 802 | ```ls ~/.ssh``` 803 | eg: default names:``` id_rsa.pub ``` ``` id_rsa `` 804 | Here id_rsa is the private key. 805 | Files ending with the .pub are the public key which is to be added to the ```authorized_keys`` on remote servers. 806 | For GitHub, go to Settings click on SSH and GPG keys 807 | 2. Choose SSH-keys, give it a name and the .pub file. 808 | ``` cat ~/.ssh/id_rsa.pub ``` copy and paste this to the key section. 809 | 810 | ``` Scenario 2 creating a new key ``` 811 | 1. Using ssh-keygen we will create keys. 812 | ``` ssh-keygen -t rsa -b 4096 ``` 813 | t-flag: for choosing encryption methods such as RSA,DSA,ECDSA. 814 | b-flag: for choosing no. of bits. 815 | with help of man command you can know more about ssh-keygen. 816 | 2. It will prompt for the name and location for the keys: 817 | default: ```/home/[user]/.ssh/id_rsa``` 818 | You can choose this, if there is an existing key it will overwrite it. 819 | 3. Pick a relevant name: ```/home/[user]/.ssh/id_rsa_[github|Server A]``` 820 | 4. It will ask for passphrase, you can avoid this or enter passphrase which will be asked whenever your using this key. Enter the same passphrase again to confirm it. 821 | 5. Thus you have created the keys(public and private). Sometimes you have to add the generated private key to cache by using ```ssh-add ~/.ssh/[filename]``` 822 | 6. Copy the public key using cat command. 823 | eg:``` cat ~/.ssh/[file_name.pub] ``` 824 | 7. Add this key to GitHub, by going to Settings and then click on SSH and GPG keys, give a name and paste it. 825 | 826 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | MIT License 2 | 3 | Copyright (c) 2019 iamshm 4 | 5 | Permission is hereby granted, free of charge, to any person obtaining a copy 6 | of this software and associated documentation files (the "Software"), to deal 7 | in the Software without restriction, including without limitation the rights 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 | copies of the Software, and to permit persons to whom the Software is 10 | furnished to do so, subject to the following conditions: 11 | 12 | The above copyright notice and this permission notice shall be included in all 13 | copies or substantial portions of the Software. 14 | 15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 21 | SOFTWARE. 22 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 |

Linux/Unix Commands

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Operating Linux becomes easy if you know the right commands

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6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | A community-built repository which includes most of the basic command lines. 15 | 16 |

17 | 18 | ## What is this repository for? 19 | 20 | This is list of many useful basic linux command lines. 21 | 22 | ## Who can contribute for this repository? 23 | 24 | Anyone. Absolutely anyone can contribute to this repository. Please check the rules below before you make pull requests. 25 | 26 | # CONTRIBUTION 27 | 28 | ## How to contribute? 29 | 30 | - Add an issue to this repository stating the use of that command line. 31 | - Fork this repository and give a star. 32 | - Try to provide examples for that command line. 33 | - Once go through the raw file of `Commands.md` to get the gist of formatting required. 34 | - Add it to the`Commands.md` file. 35 | - Create a Pull request 36 | - Feel free to improve the README.md 37 | 38 | ## Rules 39 | ### Please follow format used in `Commands.md` 40 | - Please do not spam pull request for the sake of Hacktoberfest. 41 | - No duplicate entries. Please check if the command is existing before you submit. 42 | - Star this repository to show appreciation towards public efforts. 43 | --------------------------------------------------------------------------------