229 Basic Linux Commands with Examples: Definitive Cheat Sheet List

In this blog post, we’ll take a look at 229 of the most useful Linux commands.

We’ll also discuss how to use them, and provide some examples on how they can be used in real-world scenarios. So, if you’re looking to learn more about Linux commands, read on!

1. admin Command

admin command is a source code control system command, used to create and administer SCCS files.

Some examples admin of Command:

admin

2. alias Command

alias command instructs the shell to replace one string with another string while executing the commands.

Some examples of alias Command:

To print all aliases

alias -p

Remove aliases

unalias [alias name]

Create new aliases

alias [alias name]

3. ar Command

ar command is used to create, modify and extract the files from archives. r syntax is used to create archive files, while q is used to delete archive files.

Some examples of ar Command:

Ar command follows this

ar [OPTIONS] archive_name member_files

Lets say you have an ssl certificate yesterblog.crt that you want to put in an archive folder you want to create with ar command, named certificates. You use the command below.

ar r yesterblog.crt *certificates

4. apt Command

apt is a command-line utility for installing, updating, removing, and otherwise managing deb packages on unix

Some examples of apt Command:

To update files on your server use the command below. Choose appropraite command, depending on whether you are logged in as root or sudo.

apt update

sudo apt update

To download upgrade files from repository automatically, use the commands below, depending on whether you are root or sudo.

apt-get upgrade

sudo apt-get upgrade

To update downloaded upgrades.

apt upgrade

sudo apt upgrade

5. asa Command

The asa command asa writes its input files to standard output,

Some examples of asa Command:

To view file (created by a program using FORTRAN-style carriage-control characters) on a terminal.

asa filename

formats the FORTRAN output of b.out and directs it to the printer.

b.out | asa | lp

6. at Command

at command is a command-line utility that is used to schedule a command to be executed at a particular time in the future. at Command is similar to cron job.

Unlike cron, at command does the job once, not repeatedly like cron.

Before you can use at command, you need to install the at command on your server, be it ubuntu or centos.

To install at command on ubuntu depending on sudo or root user.

apt-get install at

sudo apt-get install at

To install at command on centos, depending on sudo or root user.

yum install at

sudo yum install at

Some examples of at Command:

To view all at pending at commands

at -l

sudo at -l

Schedule a job to run on the coming Friday.

at Friday

Schedule a job to run on the coming Friday, 50 minutes later.

at Friday +50 minutes

Schedule a job to run on a particular date and time, lets say 14th February 2022, 4:55pm

at 4:55pm 021422

Schedule system shutdown 5 hrs from now.

echo "shutdown -h now" | at now +5hrs

To delete an at command,

use the command below to list all running at commands and get the job number on the list.

at -l

Use any command below to delete at command.

at -r [job number]

atrm [job number]

7. awk Command

awk Command is used for generating reports and data manipulation. awk command can also be used for arithmetic and string operations, and conditionals and loops.

awk command can format output lines, and transform data files to produce formatted reports.

Also, it can be used to scan file line by line, perform actions on matched lines, and split each input line into fields.

Lets say you have a .txt file on your server called users.txt, and you wanted to print out the content of the .txt file, you can use awk command.

Some examples of awk Command:

awk 'print' users.txt

Output

yester ceo account 60606

blog worker account 3029

ordinary sales 540404

8. basename Command

basename Command prints the last element of a file path.

Some examples of basename Command:

basename filepath

9. bash Command

The bash command is a command line interface for the GNU operating system. It is a shell that provides both interactive and non-interactive use.

The bash command has been around since the early days of Unix, but it was not until Version 4.0 that it became widely used.

The bash command is often used to automate tasks in Linux and Unix-like operating systems, such as running a program or script at regular intervals, sending commands to another computer on a network, or updating files with another computer on the network.

Some examples of bash Command:

bash [options] [file]

10. batch Command

batch Command similar to htop command, is used to read commands from standard input or a specified file and execute them when system load levels permit

To use batch Command, type batch in command line:

batch

11. bc Command

bc Command also known as basic calculator command, is a command used to do basic arithmetic calculations. some of its options

Options:

h (help) – get help
i (interactive) : Enforce interactive mode
l (mathematics library or mathlib) : Define standard math library
w (warn) : Give warnings to POSIX bc
s (standard) : process exactly the POSIX bc language
q (quiet) Stop showing welcome print
v (version) : Show bc calculator version

basic calculator command supports many types of calculations:

Arithmetic operators
Increment or Decrement operators
Assignment operators
Comparison or Relational operators
Logical or Boolean operators
Math functions
Conditional statements
Iterative statements

Some examples of bc Command:

1. Basic arithmetic:

$ echo "2+2" | bc
4
$ echo "10-5" | bc
5
$ echo "3*4" | bc
12
$ echo "8/4" | bc
2

2. Using variables:

$ echo "a=4" | bc
4
$ echo "b=6" | bc
6
$ echo "a*b" | bc
24

3. Performing square root and exponentiation:

$ echo "sqrt(4)" | bc
2
$ echo "10^3" | bc
1000

4. Using functions:

$ echo "define add(a,b) { return a+b }" | bc
$ echo "add(4,5)" | bc
9

5. Using if statements:

$ echo "if (1 > 2) print 1 else print 0" | bc
0

6. Using while loops:

$ echo "i=0; while (i<10) { print i; i=i+1 }" | bc
0
1
2
3
4
5
6
7
8
9

12. bg Command

The bg command in Linux is used to background a process that was previously put into the foreground. This allows you to continue working in the terminal while the process continues to run in the background.

The basic syntax for the bg command is:

bg [job_id]

Where job_id is the ID of the process you want to background. If you do not specify a job ID, the bg command will background the most recently stopped or suspended process.

Here are a few examples:

To background the process with ID 1234:

bg 1234

13. break Command

In Linux and Unix-like systems, the break command is used to exit from a loop. It can be used in both shell scripts and programming languages like C and C++ that have loop constructs such as for, while, and do-while.

When used in a shell script, break terminates the execution of the current loop and resumes execution at the next command after the loop.

Here’s an example of using break in a for loop in a shell script:

for i in {1..10}; do
  if [ $i -eq 5 ]; then
    break
  fi
  echo $i
done

14. c99 Command

c99 is a command line utility for compiling C99 source code. C99 is a standard for the C programming language that was first published in 1999 and introduced several new features and improvements to the language, such as variable-length arrays and new data types.

Here’s an example of using c99 to compile a C99 source code file called myprogram.c into an executable file called myprogram:

c99 myprogram.c -o myprogram

15. cal Command

The cal command in Linux is used to display a calendar for the current month or a specified month and year. The command is typically used to quickly view the days of the month and can be useful for scheduling and planning tasks.

The basic syntax for the cal command is:

cal [options] [[month] year]

Where options are any command line options you want to pass to the command and [[month] year] are the month and year for which you want to display the calendar. If you do not specify a month and year, the calendar for the current month will be displayed.

Here are a few examples:

To display the calendar for the current month:

cal

cal is a command-line utility used to print out calendar in the terminal.

16. cat Command

The “cat” command is a Linux command that is used to concatenate and display the contents of one or more files in the terminal. It stands for “concatenate,” and it is used to display the contents of a file, or to concatenate multiple files and display the output.

The basic syntax of the command is:

cat file1 file2 file3

17. cd Command

The cd (change directory) command in Linux is used to change the current working directory of a terminal session. The current working directory is the directory that the terminal is currently “looking at” and where commands are executed.

Here are some examples of how to use the cd command:

cd: This command, used by itself, will take you to your home directory. For example, if your username is “john,” running cd will take you to the directory at /home/john/.
cd /: This command will take you to the root directory of the file system. This is the top-level directory that contains all other directories and files on the system.

18. cflow Command

cflow Command analyzes the C, C++, yacc, lex, assembler, and object files and writes a chart of their external references to standard output.

Here are some examples of how to use the cflow command:

cflow main.c : This command will generate a call graph of the C program in the file main.c and display it on the terminal.
cflow -b main.c : This command will generate a call graph as before, but will also include macro expansions in the output
cflow -o graph.dot main.c : This command will generate a call graph in the Graphviz’s dot format and save it to the file ‘graph.dot’
cflow -n main.c : This command will generate a call graph, but only include functions defined in the input file and exclude system functions

19. chgrp Command

The chgrp Command is a command that can be used to change the group ownership of a file or directory.

The chgrp Command is used to change the group ownership of a file or directory. It can be used to change the group ownership of files and directories in Linux, Mac OS X, and Unix-like operating systems.

The chgrp Command is also known as “chmod” in Unix-like operating systems.

Here are some examples of how to use the chgrp command:

chgrp group file.txt: This command will change the group ownership of the file file.txt to group.
chgrp -R group dir : This command will change the group ownership of the directory dir and all the files and directories inside it to group
chgrp -h symlink : This command will change the group ownership of the symlink ‘symlink’ instead of the file or directory it points to

20. chmod Command

In Linux and other Unix-like operating systems, the chmod command is used to change the permissions of a file or directory. The permissions determine who is able to read, write, and execute a file or list the contents of a directory.

The chmod command takes two arguments: the permissions you want to set, and the file or directory whose permissions you want to change.

The permissions are specified using a combination of letters and numbers. There are three types of permissions that can be set: read (r), write (w), and execute (x). These permissions can be set for three different classes of users: the file owner (u), the members of the file’s group (g), and all other users (o).

To specify the permissions, you can use either letters or numbers. Here are some examples:

chmod u+x file.txt – This gives the owner of the file execute permissions.
chmod g-w file.txt – This removes write permissions for the members of the file’s group.
chmod o=r file.txt – This sets read permissions for others.
chmod 755 /path/to/directory – This sets read, write and execute permissions for the owner and read and execute permissions for group and others.

See all examples of chmod Command

21. chown Command

The chown command (short for “change owner”) is a command used in Linux and Unix-based operating systems to change the ownership of a file or directory. The command takes two arguments: the first is the name of the user who will become the new owner of the file or directory, and the second is the file or directory whose ownership will be changed.

Here are some examples of how chown command can be used:

To change the ownership of a file named file.txt to user named “yesterblog”:

chown yesterblog file.txt

22. chroot Command

The chroot command is used in Linux to change the root directory for a running process and its children. This can be useful for running a program with a different filesystem environment than the host system.

Here are a few examples of how to use the chroot command:

To change the root directory of a command to a directory called /newroot, use the following command:

sudo chroot /newroot command

23. cksum Command

The cksum command in Linux is used to calculate the cyclic redundancy check (CRC) and byte count of a file. The output of the command includes the CRC value, the byte count of the file, and the name of the file.

Here are a few examples of how to use the cksum command:

To calculate the CRC and byte count of a file called file.txt, use the following command:

cksum file.txt

24. clear Command

The clear command is a command-line utility on Linux and other Unix-like operating systems that is used to clear the terminal screen. Here are a few examples of how to use the clear command:

To clear the terminal screen, simply type clear and press Enter.

$ clear

You can also use the keyboard shortcut Ctrl + L to achieve the same result.

25. cmp Command

The cmp command is a command-line utility on Linux and other Unix-like operating systems that is used to compare the contents of two files. It returns an exit status of 0 if the files are identical, and a non-zero exit status if the files are different. Here are a few examples of how to use the cmp command:

To compare the contents of two files, you can use the following syntax:

$ cmp file1 file2

You can also compare the contents of two files and display the offset of the first byte that differs by using the -l option:

$ cmp -l file1 file2

26. comm Command

The comm command is a command-line utility on Linux and other Unix-like operating systems that is used to compare the contents of two sorted files. It takes two files as input and produces three columns of output: lines unique to the first file, lines unique to the second file, and lines common to both files. Here are a few examples of how to use the comm command:

To compare the contents of two sorted files, you can use the following syntax:

$ comm file1 file2

If you want to suppress the column of lines that are unique to the first file, you can use the -1 option:

$ comm -1 file1 file2

27. command Command

he command command is used in a Linux or Unix shell to run a specified command and bypass any function or alias that may be defined with the same name as the command being run. This can be useful in situations where you want to use the built-in version of a command rather than a function or alias that you have defined.

Here are some examples of how command can be used:

To run the built-in version of the ls command:

command ls

28. compress Command

Here are some examples of how to use the compress command:

compress file.txt: This command will compress the file file.txt and create a new file named file.txt.Z. The original file will be kept, but its contents will be replaced with the compressed version.
compress -v file.txt : This command will compress the file file.txt and create a new file named file.txt.Z and also displays the percentage reduction of the file size

The compress command is a new feature in the latest version of the Linux kernel. It compresses files and folders by removing unnecessary data.

The compress command is a new feature in the latest version of the Linux kernel. It compresses files and folders by removing unnecessary data. The compression ratio can be controlled with a number of options, such as -z option which will reduce file size by 50% without losing any information, or -9 option which will reduce file size by 90%.

The compress command can also be used to create archives that are compressed with gzip or bzip2 algorithms.

29. continue Command

The continue command is a shell programming command that allows you to continue the current line of code.

It can be used in many different ways, such as continuing a loop or continuing an if statement.

The continue command is often used in loops and if statements.

Here are some examples of how continue can be used in different types of loops:

In a for loop:

for i in {1..10}; do
    if [ $i -eq 5 ]; then
        continue
    fi
    echo $i
done

This script will print the numbers 1 through 10, but will skip the number 5.

30. cp Command

cp Command (copy Command), is a file system command that can be used to copy text from one file to another.

The cp command is a very useful tool for programmers and developers. It can be used to copy text from one file to another, or even between two different files.

The cp command is also useful for copying text from the terminal into a file.

To copy a file to a different location:

cp file1.txt /path/to/destination

To copy multiple files to a different location:

cp file1.txt file2.txt /path/to/destination

To copy a directory and its contents to a different location:

cp -r directory1 /path/to/destination

31. crontab Command

Crontab is a command-line utility that allows users to schedule commands to be executed periodically. It can be used for scheduling tasks such as backups, sending email, and running scripts.

The crontab command can be used in Linux and Unix-like operating systems.

To edit your crontab file, use the following command: crontab -e. This opens the crontab file in the default editor for you to add or edit scheduled tasks.
To list the current crontab tasks for the current user, use the following command: crontab -l.
To remove the current user’s crontab, use the following command: crontab -r.
To add a new task to the crontab, you can use the following command: crontab -e, then enter the task in the following format on a new line:
* * * * * command - - - - - | | | | | | | | | ----- Day of week (0 - 7) (Sunday = both 0 and 7) | | | ------- Month (1 - 12) | | --------- Day of month (1 - 31) | ----------- Hour (0 - 23) ------------- Minute (0 - 59)
For example, the following command will run the script.sh file every day at 3:30am: 30 3 * * * /path/to/script.sh

32. csplit Command

The csplit command is a powerful text proccessing tool that can be used to split a file into multiple files. It is often used by developers and programmers who need to split large files into smaller ones for easier management.

The csplit command can also be used in other ways, such as splitting text files into multiple smaller text files or splitting logfiles into smaller logs.

Some examples of csplit Command:

To split a file into multiple smaller files based on a specific line number, use the following command: csplit file.txt 10 This will split the file “file.txt” into multiple files, each containing 10 lines of the original file. The resulting files will be named “xx00”, “xx01”, etc.
To split a file into multiple smaller files based on a regular expression, use the following command: csplit file.txt '/regex/' This will split the file “file.txt” into multiple files based on the location of the regular expression “regex” in the file.

33. ctags Command

ctags Command is a C programming command, used to create a tags file.

Some examples of ctags Command:

To generate a tags file for all source files in the current directory and its subdirectories, use the following command: ctags -R . This will recursively scan the directory for files and generate a “tags” file that can be used to navigate the source code.
To generate a tags file for a specific file, use the following command: ctags filename.c
To generate a tags file for specific language, use the following command: ctags -R --languages=python

34. cut Command

cut Command is a shell programming command used to cut out selected fields of each line of a file.

Some examples of cut Command:

Extract the first field (delimited by a tab character) from a file:

cut -f1 -d$'\t' file.txt

Extract the second and third fields (delimited by a comma) from a file:

cut -f2,3 -d, file.txt

Extract the first and last characters from each line of a file:

cut -c1,$ file.txt

35. cxref Command

cxref Command is a C programming category command used to generate a C-language program cross-reference table.

Some examples of cxref Command:

To generate an HTML version of the documentation for a program called “myprog.c”:

cxref -html -output myprog.html myprog.c

To generate a LaTeX version of the documentation for multiple C files “file1.c”, “file2.c”, “file3.c”:

cxref -latex -output myprog.tex file1.c file2.c file3.c

36. datamash Command

datamash is a command-line program which performs basic. numeric, textual and statistical operations on input textual data files.

Some examples of datamash Command:

To calculate the sum, minimum, and maximum of the values in the second column of a CSV file:

datamash sum 1 min 2 max 2 < input.csv

To group the data by the first column and calculate the mean of the values in the second column:

datamash --group 1 mean 2 < input.csv

37. date Command

date Command is used to write the date and time.

Some examples of date Command:

To display the current date and time:

date

To display the date in a specific format:

date +"%Y-%m-%d %T"

To set the date and time to a specific value:

sudo date -s "2022-12-25 12:00:00"

38. dc Command

dc command in a linux command, used to evaluate arithmetic expressions, and evaluates expressions in the form of a postfix expression.

Some examples of date Command:

To perform basic arithmetic operations:

echo "2 3 + p" | dc

This command will add 2 and 3 and print the result.

To perform advanced calculations

echo "2 3 ^ p" | dc

This command will raise 2 to the power of 3 and print the result.

To perform floating point calculations

echo "3 4 5 / * p" | dc

39. dd Command

dd Command is a filesystem command, used to convert and copy a file.

Some examples of dd Command:

To create a backup of a hard drive:

sudo dd if=/dev/sda of=~/sda-backup.img bs=1M

This command will create an image of the entire hard drive at /dev/sda in the home directory as “sda-backup.img”

To clone a hard drive to another hard drive

sudo dd if=/dev/sda of=/dev/sdb bs=1M conv=noerror

40. delta Command

delta Command is a source code control system command, used to make a delta (change) to a source code control system (SCCS) file

Some examples of delta Command:

To create a delta file of two files

delta file1 file2 > delta.d

This command will create a delta file “delta.d” containing the difference between file1 and file2.

To apply a delta file to an original file

delta -u originalfile < delta.d > newfile

41. df Command

df (disk free) Command is used to report and display the amount of available disk space for file systems on which the invoking user has appropriate read access.

Some examples of df Command:

o display disk usage of all file systems

df

To display disk usage of a specific file system

df /dev/sda1

To display disk usage in human-readable format

df -h

42. diff Command

diff Command is a text processing command used to compare two files.

Some examples of diff Command:

To compare the contents of two files:

diff file1.txt file2.txt

This command will compare the contents of file1.txt and file2.txt and display the differences between them.

To compare the contents of two directories:

diff -r dir1 dir2

43. dir Command

dir (directory) Command is a command in various computer operating systems used for computer file and directory listing.

Some examples of dir Command:

To list the files and directories in the current directory, you can use the command dir without any arguments:

dir

To list the files and directories in a specific directory, you can provide the path to the directory as an argument:

dir /path/to/directory

44. dirname Command

The dirname (directory name) Command is a type of dir (directory) Command. It is used to return the directory portion of a pathname

Some examples of dirname Command:

To display the parent directory of a given file:

dirname /path/to/file.txt

To display the parent directory of a given directory:

dirname /path/to/directory

To use the output of one command as the input to the dirname command:

dirname $(pwd)

45. dot Command

dot Command is a shell programming Command, used to execute commands in the current environment.

Some examples of dot Command:

To create a PNG image of a graph specified in a plain text file:

dot -Tpng input.dot -o output.png

To create a PDF of a graph specified in a plain text file:

dot -Tpdf input.dot -o output.pdf

To create a SVG image of a graph specified in a plain text file:

dot -Tsvg input.dot -o output.svg

46. du Command

du Command is a filesystem Command, used to estimate file space usage.

Some examples of du Command:

To display the sizes of all files and directories in the current directory:

du

To display the sizes of all files and directories in a specific directory:

du /path/to/directory

To recursively display the sizes of all files and directories within a specific directory:

du -h /path/to/directory

47. echo Command

echo Command is a shell programming command that outputs the strings that are passed to it as arguments, in standard output.

Some examples of echo Command:

Print a simple string of text:

echo "Hello, World!"

Print the value of an environment variable, such as the current working directory:

echo $PWD

Concatenate strings and print the result:

echo "Hello, " "World!"

48. ed Command

ed Command is a text processing Command, used to launch the ed standard text editor.

Some examples of ed Command:

Open a file named “file.txt” and begin editing it:

ed file.txt

Add a new line of text to the file:

a
This is a new line of text.
.
w

Print the contents of the file:

1,$p

49. env Command

env Command is used to list environment variables or invoke a command in a modified environment.

Some examples of env Command:

Display all environment variables:

env

Display the value of a specific environment variable:

env | grep HOME

Run a command with a modified environment:

env PATH="/usr/local/bin:$PATH" command

50. eval Command

eval Command is a shell programming Command is construct command by concatenating arguments.

Some examples of eval Command:

Execute a command stored in a variable:

cmd="ls -l"
eval $cmd

Concatenate variables and execute the resulting command:

var1="ls"
var2="-l"
eval $var1 $var2

Execute commands stored in an array:

cmds=("ls -l" "pwd" "whoami")
for cmd in "${cmds[@]}"; do
    eval $cmd
done

51. ex Command

ex Command is a text editor, and the line-editor mode of vi.

Some examples of ex Command:

Open a file named “file.txt” and begin editing it with vi command

vi file.txt

Then enter the command mode and type :e file2.txt to edit another file in the same session

:e file2.txt

To open multiple files in the same session, you can use :args command

:args file1.txt file2.txt file3.txt

Copy a line from a file and paste it to another file in the same session

:1,3 co 5

52. exec Command

exec command is used for manipulating file-descriptors (FD), creating output and error logging within scripts with a minimal change.

Some examples of exec Command:

Open a new shell in the current terminal:

exec bash

Open a new instance of vi:

exec vi file.txt

Run a Python script and replace the current process with it:

exec python script.py

53. exit Command

exit Command is a shell programming Command used to cause the shell to exit.

Some examples of exit Command:

Exit the current shell or terminal session:

exit

Exit a script with a specific exit code:

exit 0

Exit a script when a certain condition is met:

if [ condition ]; then
    exit 1
fi

54. expand Command

expand command is a text processing Command used to extract a single file or a group of files from a compressed file.

Some examples of expand Command:

Convert tabs to spaces in a file named “file.txt”

expand file.txt

Convert tabs to a specific number of spaces, e.g. 4

expand -t 4 file.txt

Convert tabs to spaces in the input stream, e.g. when using cat

cat file.txt | expand

55. export Command

export Command is used to set the export attribute for variables.

Some examples of export Command:

Export a new environment variable:

export VAR="value"

Export multiple environment variables at once:

export VAR1="value1" VAR2="value2"

Use export in a script to make a variable available to commands run within the script:

#!/bin/bash
export VAR="value"
command1
command2

56. expr Command

expr Command is a shell programming Command, used to valuate arguments as an expression.

Some examples of expr Command:

Perform arithmetic operations:

expr 5 + 2
expr 10 - 3
expr 3 \* 4
expr 20 / 5

Perform comparisons:

expr 5 \> 2
expr 5 \< 2
expr 5 \== 5

Perform string operations:

expr "hello" : '.*\(...\)'
expr length "hello"

57. false Command

false Command is a shell programming Command, used to return false value.

Some examples of false Command:

To create a simple shell script that always exits with a failure status:

#!/bin/bash
false

To check the exit status of a command, and take action based on whether it succeeded or failed:

command
if [ $? -eq 0 ]; then
    echo "Command succeeded"
else
    echo "Command failed"
fi

To use “false” command as a placeholder when a command must be executed but no action is required:

command || false

58. fc Command

fc Command is used to process the command history list

Some examples of fc Command:

To list the last 10 commands in your history:

fc -l -10

To list all commands in your history containing the word “command”:

fc -l | grep command

To edit the last command that you entered:

fc

59. fg Command

fg (fore ground) Command is a process management Command, used to run jobs in the foreground.

Some examples of fg Command:

To bring the most recent background process to the foreground:

fg

To bring a specific background process to the foreground by its job ID:

fg %1

In this example, the process with the job ID of 1 will be brought to the foreground.

To bring a specific background process to the foreground by its command name:

fg %command

60. file Command

file Command is a filesystem Command used to determine file type.

Some examples of file Command:

To determine the type of a file:

file file.txt

This will return a string describing the type of the file, for example: “file.txt: ASCII text”

To check multiple files at once:

file file1.txt file2.jpg file3.mp3

To print detailed information about the file format

file -b -L --mime-type filename

61. find Command

find Command is a filesystem Command used to find files.

Some examples of find Command:

To search for all files and directories in the current directory:

find .

To search for all files with the .txt extension in the current directory and its subdirectories:

find . -name '*.txt'

To search for all files that were modified in the last 24 hours:

find . -mtime -1

62. flex Command

flex Command is a C programming command, used to generate programs for lexical tasks.

Some examples of flex Command:

Creating a simple lexer for a simple calculator:

%{
#include <stdio.h>
%}

%%
[0-9]+  { printf("number: %s\n", yytext); }
[ \t]   ; /* ignore whitespace */
.       { printf("unexpected character: %s\n", yytext); }
%%

int main(int argc, char* argv[]) {
    yyparse();
    return 0;
}

63. fold Command

fold Command is a text processing command, used to filter for folding lines.

Some examples of fold Command:

Wrapping lines to a width of 80 characters:

fold -w 80 input.txt > output.txt

Wrapping lines to a width of 40 characters and displaying the result on the screen:

fold -w 40 -s input.txt

64. fort77 Command

fort77 Command is a C Programming, for Fortran compiling.

Some examples of fort77 Command:

Compile a FORTRAN 77 source file, “program.f” into an object file “program.o”:

fort77 -c program.f

Compile and link a FORTRAN 77 source file, “program.f” into an executable file “program”:

fort77 program.f -o program

Compile a FORTRAN 77 source file, “program.f” and specify include paths, for example, to include “-I/path/to/headers”:

fort77 -I/path/to/headers -c program.f

65. fortune Command

fortune Command is used to displays a random quotation.

Some examples of fortune Command:

Display a random fortune to the terminal:

fortune

Display a fortune from a specific file, for example from the fortunes-off file

fortune fortunes-off

Display a fortune with a specific cookie file, for example from the “funny” category:

fortune funny

66. ftp Command

ftp (file transfer protocol) Command is used for internet file transfer between machines or programs.

Some examples of ftp Command:

Connect to an FTP server and login as a user:

ftp ftp.example.com

You will be prompted for your username and password

Connect to an FTP server with a specific username and password:

ftp ftp.example.com -u ftpusername -p ftppassword

67. fuser Command

fuser Command is a process Management Command, used to list process IDs of all processes that have one or more files open.

Some examples of fuser Command:

Identify which process(es) are using a specific file:

fuser file.txt

Identify which process(es) are using a specific file and display the command name of the process:

fuser -c file.txt

Identify which process(es) are using a specific file system, for example, the /tmp file system

fuser -m /tmp

68. gawk Command

gawk Command is a text processing Command used for pattern scanning and processing language, GNU’s version of awk.

Some examples of gawk Command:

Print the first field of each line in a file:

gawk '{print $1}' file.txt

Print the second and third fields of each line, separated by a comma:

gawk '{print $2, $3}' file.txt

Print the number of fields in each line:

gawk '{print NF}' file.txt

69. gencat Command

gencat (generate catalogue) Command is used to generate a formatted message catalog.

Some examples of gencat Command:

Create a message catalog from a source file:

gencat messages.cat messages.po

Update an existing message catalog with new translations from a source file:

gencat -u messages.cat messages.po

Generate a message catalog and specify the output format:

gencat -f iso-2022-jp messages.cat messages.po

70. get Command

get Command is a source code control system command used to the get version of a source code control system file.

Some examples of get Command:

curl command is used to transfer data from or to a server using various protocols such as HTTP, HTTPS, FTP, etc.

curl -O http://example.com/file.txt   # download a file

wget command is used to download files from the internet.

wget http://example.com/file.txt   # download a file

scp command is used to copy files between hosts on a network.

scp [email protected]:/path/to/file.txt .  # copy file from remote host

71. getconf Command

getconf (get configuration) Command is used to get configuration values of installations.

Some examples of getconf Command:

Display the system’s maximum number of open files:

getconf OPEN_MAX

Display the system’s page size:

getconf PAGESIZE

Display the system’s path name delimiter:

getconf PATH_MAX

72. getopts Command

getopts Command is a shell programming Command, used to parse utility options.

Some examples of getopts Command in bash script:

#!/bin/bash

while getopts ":a:b:" opt; do
  case $opt in
    a)
      arg_a="$OPTARG"
      ;;
    b)
      arg_b="$OPTARG"
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit 1
      ;;
    :)
      echo "Option -$OPTARG requires an argument." >&2
      exit 1
      ;;
  esac
done

echo "arg_a: $arg_a"
echo "arg_b: $arg_b"

73. grep Command

grep Command is used to search for text pattern and strings, in a group of files.

Some examples of grep Command:

Search for a specific string in a file:

grep "search_string" file.txt

Search for a pattern in multiple files

grep "search_pattern" file1.txt file2.txt file3.txt

Search for a pattern in all files in a directory recursively:

grep -r "search_pattern" /path/to/directory/

74. groupadd Command

groupadd Command is used to create and add a new group to terminal.

Some examples of groupadd Command:

Create a new group:

groupadd newgroup

This command creates a new group called “newgroup” on the system.

Create a new group with a specific GID(group id):

groupadd -g 1025 newgroup

This command creates a new group called “newgroup” with a GID of 1025.

Create a new group and assign a password to it:

groupadd -p password newgroup

75. groupdel Command

groupdel Command is used to delete an existing group from terminal.

Some examples of groupdel Command:

Delete an existing group:

groupdel existinggroup

76. groups Command

groups Command is used to list groups a user belongs to

Some examples of groups Command:

Display the groups for the current user:

groups

Display the groups for a specific user:

groups username

Display the groups for multiple users

groups user1 user2 user3

77. hash Command

hash Command is used to remember or report utility locations.

Some examples of hash Command:

To remember the full path of the ls command, you can run the following command:
hash ls
To display all commands that have been hashed, use the -l option:Copy codehash -l
You can also use -r option with hash command to clear the remembered path of a command
hash -r ls
You can also use -d option with hash command to remove the remembered path of a command
hash -d ls

78. head Command

head Command is a text processing Command used to copy the first part of files.

Some examples of head Command:

To display the first 10 lines of a file called “example.txt”, you can run the following command:
head example.txt
To display the first 15 lines of the same file, you can use the -n option:
head -n 15 example.txt
To display the first 20 lines of a file and also show the line number , you can use the -n and -v option:
head -n 20 -v example.txt

79. history Command

history Command is used to show history of all commands ever used on a terminal.

Some examples of history Command:

To display the history of commands in the current terminal session, you can simply run the following command:
history
To display the history of commands with line numbers, use the -n option:
history -n
To display a specific number of previous commands from the history, use the -n option followed by a number. For example, to display the last 20 commands:
history 20

80. hostname Command

hostname is a networking command used to show the system’s host name.

Some examples of hostname Command:

To display the current hostname of the system, you can simply run the following command:
hostname
To set the hostname of the system, you can use the -s option followed by the new hostname. For example, to set the hostname to “my-server”:
hostname -s my-server Note that this command will change the hostname for the current session, but the change will not persist after reboot.

81. htop Command

htop Command does the same thing on terminal, which task manager does on windows. htop Command shows terminal processes in real time, and the amount of system resources they are consuming.

Some examples of htop Command:

To start htop and view the running processes and their usage, you can simply run the following command:
htop

82. iconv Command

iconv command converts the encoding of characters read from either standard input or the specified file from one coded character set to another and then writes the results to standard output.

Some examples of iconv Command:

To convert a file from UTF-8 to ISO-8859-1, you can run the following command:
iconv -f UTF-8 -t ISO-8859-1 inputfile.txt -o outputfile.txt
To convert a file from Shift-JIS to UTF-8, you can use the following command:
iconv -f Shift-JIS -t UTF-8 inputfile.txt -o outputfile.txt

83. id Command

id (identity) Command is used to return a users identity.

Some examples of id Command:

To display information about the current user, simply type id and press enter:

$ id
uid=1000(jdoe) gid=1000(jdoe) groups=1000(jdoe),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),108(lxd)

To display information about a specific user, provide the username as an argument to the command:

$ id jdoe
uid=1000(jdoe) gid=1000(jdoe) groups=1000(jdoe),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),108(lxd)

84. iostat Command

iostat Command is used to collect and show operating system storage input and output statistics.

Some examples of iostat Command:

To display the average CPU utilization and disk usage statistics since the system was last booted, simply type iostat and press enter:

$ iostat
Linux 4.15.0-114-generic (jdoe-linux)   07/25/2023    _x86_64_    (8 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           5.67    0.00    3.33    0.33    0.00   90.67

Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
sda               0.00         0.00         0.00          0          0
sdb               0.00         0.00         0.00          0          0

85. ipcrm Command

ipcrm command removes one or more message queues, semaphore sets, or shared memory identifiers

Some examples of ipcrm Command:

To remove a shared memory segment identified by a specific ID:

$ ipcrm -m 1234

To remove a message queue identified by a specific ID:

$ ipcrm -q 1234

To remove a semaphore set identified by a specific ID:

$ ipcrm -s 1234

86. ipcs Command

ipcs is a Unix and Linux command to list System V InterProcess Communication System’s API kernel entities to stdout. It also report interprocess communication facilities status.

Some examples of ipcs Command:

To display information about all shared memory segments on the system:

$ ipcs -m

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00001234 0          root       600        32768      0                           
0x00005678 65537      jdoe       600        16384      0

To display information about all message queues on the system:

$ ipcs -q

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages    
0x00001234 0          root       666        0            0            
0x00005678 65537      jdoe       666        0            0

87. jobs Command

jobs Command display status of jobs in the current session

Some examples of jobs Command:

To view a list of all background jobs, simply run “jobs” without any arguments:

$ jobs

To bring a background job back to the foreground, you can use the “fg” command followed by the job number:

$ fg %3

To send a background job to the background, you can use the “bg” command followed by the job number:

$ bg %2

88. join Command

join command provides us with the ability to merge two files together using a common field in each file as the link between related lines in the files.

Some examples of join Command:

To join two files, file1.txt and file2.txt on the first field:

$ join file1.txt file2.txt

To join two files, file1.txt and file2.txt on the second field:

$ join -1 2 -2 2 file1.txt file2.txt

To join two files and use a different delimiter (e.g., “:”):

$ join -t : file1.txt file2.txt

89. kill Command

kill Command is a built-in command which is used to terminate processes.

Some examples of kill Command:

To terminate a process by its PID (process ID), you can use the command:

$ kill PID

where “PID” is the process ID of the process you want to terminate.

To terminate a process by its name, you can use the command

$ pkill process_name

90. last Command

last command is used to displays information about the last logged-in users.

Some examples of last Command:

To view the last logged in users

$ last

To show the last logins for a specific user

$ last username

91. less Command

less Command is a Linux utility that can be used to read the contents of a text file one page(one screen) at a time.

Some examples of less Command:

To view a text file one page at a time, use the following command:

$ less file.txt

Where “file.txt” is the name of the file you want to view.

To search for a specific word or phrase within a file:

$ less file.txt
/search-string

92. lex Command

lex Command is a C programming command used to generate programs for lexical tasks.

Some examples of lex Command:

To generate a lexer from a lexer specification file “example.l”

$ lex example.l

This will output a C file called lex.yy.c, which contains the lexer code.

To generate a lexer and specify the output file name.

$ lex example.l -o example_lexer

93. link Command

link Command is a filesystem utility used to call link function.

Some examples of link Command:

To create a hard link to a file, use the following command:

$ ln original_file hard_link

Where “original_file” is the name of the existing file, and “hard_link” is the name of the new hard link.

To create a symbolic link to a file:

$ ln -s original_file symbolic_link

94. ln Command

ln Command is a filesystem command-line utility for creating links between files.

Some examples of ln Command:

To create a hard link to a file, use the following command:

$ ln original_file hard_link

Where “original_file” is the name of the existing file, and “hard_link” is the name of the new hard link.

To create a symbolic link to a file:

$ ln -s original_file symbolic_link

95. locale Command

locale Command is a linux command used to get locale-specific information.

Some examples of locale Command:

To display the current locale settings:

$ locale

To display the current settings for a specific category, you can use the option “-k” and category name like this

$ locale -k LC_TIME

96. localedef Command

localedef Command is used to define locale environment.

Some examples of localedef Command:

To create a new locale from a template file:

$ localedef -f UTF-8 -i template_file new_locale

Where “template_file” is the name of the file containing the locale definition, and “new_locale” is the name of the new locale.

To modify an existing locale:

$ localedef -f UTF-8 -i existing_locale modified_locale

97. locate Command

locate command in Linux is used to find the files by name.

Some examples of locate Command:

To find all files in the system that have the word “example” in their name:
locate -i example
To find all files in the system that have the extension “.txt”:
locate -i .txt

98. logger Command

logger Command is a shell programming Command, used to log messages.

Some examples of logger Command:

To log a message to the system’s default log file (typically /var/log/messages):
logger "this is a test message"
To log a message to the system’s auth log file (typically /var/log/auth.log):
logger -p auth.notice "this is a test message"

login

100. logname Command

logname Command is used to return the user’s login name.

Logname Command:

logname

101. logout Command

logout command allows you to logout from your current session.

Some examples of logout Command:

logout

102. lp Command

lp Command is a text processing command used to send files to a printer.

Some examples of lp Command:

To print a file named “file.txt” to the default printer:

lp file.txt

To print a file named “file.txt” to a specific printer:

lp -d printer_name file.txt

103. ls Command

ls Command is a filesystem Command used to list directory contents.

Some examples of ls Command:

To list the files and directories in the current directory:

ls

To list the files and directories in a specific directory:

ls /path/to/directory

To list the files and directories in a directory in a long format, showing details such as file permissions, owner, and size:

ls -l

104. m4 Command

m4 Command is used for macro processing.

Some examples of m4 Command:

Define a macro named greeting and expand it in a file named hello.txt:

$ echo 'greeting(Hello, World!)' > hello.txt
$ m4 -Dgreeting='Hello, World!' hello.txt
Hello, World!

Include the contents of a file named header.m4 in the current file:

$ echo 'Hello, World!' > header.m4
$ echo 'include(header.m4)' > hello.txt
$ m4 hello.txt
Hello, World!

105. mailx Command

mailx Command is a linux command used for process messages.

Some examples of mailx Command:

Send a simple email to an address:

$ echo 'This is the body of the email.' | mailx -s 'Hello, World!' [email protected]

This will send an email with the subject “Hello, World!” and the body “This is the body of the email.” to the email address [email protected]

Send an email with attachment

$ echo 'This is the body of the email.' | mailx -s 'Hello, World!' -a file.txt [email protected]

106. make Command

make Command is a shell programming utility used to maintain, update, and regenerate groups of programs.

Some examples of make Command:

$ cat Makefile
CC = gcc
CFLAGS = -Wall -g

all: main.o func.o
    $(CC) $(CFLAGS) -o myprogram main.o func.o

main.o: main.c
    $(CC) $(CFLAGS) -c main.c

func.o: func.c
    $(CC) $(CFLAGS) -c func.c

clean:
    rm -f myprogram main.o func.o

$ make

107. man Command

man Command is used to display system documentation.

Some examples of man Command:

View the manual page for the ls command:

$ man ls

This will display the manual page for the ls command, which provides information on how to use ls to list the contents of a directory, as well as information about the various options that can be used with ls.

Search for a keyword in all available manual pages:

$ man -K keyword

108. mesg Command

mesg Command is used to permit or deny messages.

Some examples of mesg Command:

Allow other users to send messages to your terminal:

$ mesg y

This will set the terminal to allow other users to send messages to your terminal.

Disallow other users to send messages to your terminal:

$ mesg n

109. mkdir Command

mkdir Command is a filesystem command, used make directories.

Some examples of mkdir Command:

Create a new directory called “test” in the current directory:

mkdir test

Create a new directory called “test” in the /home/ directory:

mkdir /home/test

110. mkfifo Command

mkfifo Command is a filesystem Command used to make FIFO special files.

Some examples of mkfifo Command:

Create a named pipe called “mypipe”:

mkfifo mypipe

Create a named pipe with a specific permission:

mkfifo -m 666 mypipe

The -m option is used to specify the permission mode of the named pipe.

Create multiple named pipes at once:

mkfifo pipe1 pipe2 pipe3

111. mktemp Command

mktemp Command is a filesystem Command used to create a temporary file or directory.

Some examples of mktemp Command:

Create a temporary file with a unique name:

mktemp

This command will create a file in the default temporary directory (usually /tmp/) with a unique name such as /tmp/tmp.XXXXXXXXXX.

Create a temporary file with a specific prefix:

mktemp mytemp.XXXXXXXXXX

112. more Command

more Command displays files on a page-by-page basis

Some examples of more Command:

Display the contents of a file called “file.txt”:

more file.txt

Display the contents of a file called “file.txt” and search for a specific word:

more +/word file.txt

The +/ option is used to start the display at the first occurrence of the specified word.

Display the contents of a file called “file.txt” and start displaying at a specific line number:

more +50 file.txt

113. mount Command

mount Command is a filesystem command, used to mount a file system.

Some examples of mount Command:

Mount a file system located on the device /dev/sda1 to the mount point /mnt/:

mount /dev/sda1 /mnt/

Mount a file system with specific options:

mount -t ext4 -o rw,noatime /dev/sda1 /mnt/

The -t option is used to specify the file system type, the -o option is used to specify the mount options.

Mount a file system located on a remote host:

mount -t nfs -o rw,proto=tcp,port=2049 host:/ /mnt/

114. mtail Command

mtail command, as the name implies, print the last N number of data of the given input.

Some examples of mtail Command:

Extract metrics from a log file and print them to the console:

mtail -logfile=access.log -progs=my_metrics.mtail

The -logfile option is used to specify the log file from which metrics will be extracted, the -progs option is used to specify the mtail program file that contains the metrics extraction rules.

Extract metrics from a log file and export them to a Prometheus exporter:

mtail -logfile=access.log -progs=my_metrics.mtail -exporter=prometheus

The -exporter option is used to specify the exporter to which metrics will be exported.

Extract metrics from multiple log files and export them to a Prometheus exporter:

mtail -logfile=access.log -logfile=error.log -progs=my_metrics.mtail -exporter=prometheus

115. mv Command

mv command that moves one or more files or directories from one place to another. If both filenames are on the same filesystem, this results in a simple file rename; otherwise the file content is copied to the new location and the old file is removed.

Some examples of mv Command:

Move a file called “file.txt” from the current directory to a directory called “documents”:

mv file.txt documents/

Rename a file called “file.txt” to “newfile.txt” in the current directory:

mv file.txt newfile.txt

Move multiple files to a directory:

mv file1.txt file2.txt file3.txt documents/

116. nano Command

nano Command is a text Programming Command, used to display a small text editor.

Some examples of nano Command:

Open and edit a file called “file.txt”:

nano file.txt

Create and edit a new file called “newfile.txt”:

nano newfile.txt

Open a file in read-only mode:

nano -m file.txt

117. netstat Command

netstat Command is a networking Command, used to displays network information and statistics.

Some examples of netstat Command:

Display active connections and listening ports:

netstat -anp

The -a option shows all connections and listening ports, the -n option shows numerical addresses instead of trying to determine hostnames and -p option shows the PID and name of the program to which each socket belongs.

Display information only for a specific protocol:

netstat -tuln

The -t option shows only TCP connections, -u shows only UDP connections, -l shows only listening sockets, and -n shows numerical addresses instead of trying to determine hostnames.

Display the routing table:

netstat -r

118. newgrp Command

newgrep Command is used to change to a new group.

Some examples of newgrp Command:

Change the current group ID to the group “developers”:

newgrp developers

Change the current group ID to the group “developers” and run a command with that group ID:

newgrp developers -

Change the current group ID to the group “developers” and run a command with that group ID and login shell.

newgrp developers -l

119. nice Command

nice Command is a process Management to invoke a utility with an altered nice value.

Some examples of nice Command:

Run a program called “myprogram” with a lower priority:

nice myprogram

Run a program called “myprogram” with a lower priority and specify a priority value:

nice -n 10 myprogram

120. nl Command

nl Command is a text processing Command used for line numbering filter.

Some examples of nl Command:

Number the lines of a file called “file.txt”:

nl file.txt

Number the lines of a file called “file.txt” and start the line numbering with a specific number:

nl -v 5 file.txt

The -v option is used to specify the starting line number.

Number the lines of a file called “file.txt” and use a specific number separator:

nl -s ':' file.txt

121. nm Command

nm Command is a C Programming, used write the name list of an object file.

Some examples of nm Command:

Display the symbol table of a binary file called “mybinary”:

nm mybinary

Display the symbol table of a shared library called “libmylibrary.so”:

nm libmylibrary.so

122. nohup Command

nohup Command is a process Management Command, used to invoke a utility immune to hangups.

Some examples of nohup Command:

Run a command in the background and ignore the HUP (hangup) signal:

nohup command &

Run a command and redirect output to a file:

nohup command > output.file &

123. od Command

od Command is used to dump files in various formats.

Some examples of od Command:

To display the contents of a file in octal format: od -c file.txt
To display the contents of a file in decimal format: od -d file.txt
To display the contents of a file in hexadecimal format: od -x file.txt

124. parallel Command

parallel Command is a shell utility for executing jobs in parallel.

Some examples of parallel Command:

To run multiple commands in parallel, simply list them one after the other, separated by &:

command1 &
command2 &
command3 &

To run multiple commands in parallel and use the output of one command as input to another command:

command1 | parallel --pipe command2

125. passwd Command

passwd Command is a system Command used to set or change user password.

Some examples of passwd Command:

To change the password for the current user: passwd
To change the password for a specific user: sudo passwd username
To change the password for a user, but not require the user to provide their current password: sudo passwd -f username

126. paste Command

paste Command is a text processing, used to merge corresponding or subsequent lines of files.

Some examples of paste Command:

To concatenate the contents of two files side by side: paste file1.txt file2.txt
To concatenate the contents of multiple files side by side: paste file1.txt file2.txt file3.txt

127. patch Command

patch Command is a text processing utility to apply changes to files.

Some examples of patch Command:

To apply a patch file to a file: patch < patchfile.diff
To apply a patch file to a file and create a backup copy of the original file: patch -b < patchfile.diff
To apply a patch file to a file and ignore whitespace differences: patch -l < patchfile.diff

128. pathchk Command

pathchk Command is a filesystem utility used to check pathnames.

Some examples of pathchk Command:

To check if a file named “example.txt” has a valid filename (no invalid characters, not too long), you can use the following command:

pathchk example.txt

To check if a directory named “example_dir” has a valid pathname, you can use the following command:

pathchk -p example_dir

To check if the current directory has a valid pathname, you can use the following command:

pathchk -p .

129. pax Command

pax Command is a portable archive interchange.

Some examples of pax Command:

To archive a directory:

pax -w -f archive.pax /path/to/directory

To extract files from an archive:

pax -r -f archive.pax

To list the contents of an archive:

pax -f archive.pax -v

130. pgrep Command

pgrep Command is a process Management used to find processes with the given name using pattern matching.

Some examples of pgrep Command:

To find the PID of a process by its name:

pgrep -x process_name

To find all processes that belong to a specific user:

pgrep -u username

To search for a process by its command line arguments:

pgrep -f 'arg1 arg2'

131. ping Command

ping Command is a network administration software utility used to test the reachability of a host on an Internet Protocol network.

Some examples of ping Command:

ping google.com – sends ICMP packets to the host “google.com” and waits for replies
ping -c 5 google.com – sends 5 ICMP packets to “google.com” and then exits
ping -i 3 google.com – sends ICMP packets to “google.com” with a wait of 3 seconds between each packet

132. pkill Command

pkill Command is a process Management utility used to kill processes with the given name using pattern matching.

Some examples of pkill Command:

pkill firefox – sends the SIGTERM signal to all processes named “firefox”
pkill -9 firefox – sends the SIGKILL signal (forcefully terminate) to all processes named “firefox”
pkill -u user1 – sends the SIGTERM signal to all processes running under the user “user1”

133. pr Command

pr (print) Command is a text processing Command used to print files.

Some examples of pr Command:

pr file.txt – formats the contents of “file.txt” and sends the output to the terminal
pr -d file.txt – formats the contents of “file.txt” and adds page delimiters (form feed characters) to the output
pr -h "Title" -w 80 file.txt – formats the contents of “file.txt” and adds a header with the title “Title” and sets the line width to 80 characters

134. print Command

print Command is used to print a file directly.

Some examples of print Command:

print $HOME – prints the value of the HOME environment variable
print "Hello, world!" – prints the string “Hello, world!”
print $(pwd) – prints the output of the pwd command

135. printf Command

printf Command is a shell programming utility, used to write formatted output.

Some examples of printf Command:

printf "Hello, %s!\n" world – prints the string “Hello, world!”
printf "%.2f\n" 3.141592 – prints the number “3.14” with two decimal places
printf "The answer is %d\n" 42 – prints the string “The answer is 42”

136. prs Command

prs Command is a Source Code Control System (SCCS) Command, used to print an SCCS file.

Some examples of prs Command:

prs -e -r1.2 file.c – lists the differences between version 1.2 and the current version of “file.c”
prs -d -r1.1:1.5 file.c – lists the differences between versions 1.1 and 1.5 of “file.c”

137. ps Command

ps Command is a process Management utility, used to report process status.

Some examples of ps Command:

ps – displays a list of all processes running on the current terminal
ps -ef – displays a list of all processes on the system in a “forest” format, showing the hierarchical relationship between processes
ps -u user1 – displays a list of all processes running under the user “user1”

138. pstree Command

pstree Command is a process Management utility, used to display a tree of processes.

Some examples of pstree Command:

pstree – displays a tree of all processes running on the system
pstree -p – displays a tree of all processes running on the system and shows the process ID (PID) of each process
pstree -u user1 – displays a tree of all processes running under the user “user1”

139. pwd Command

pwd Command is a filesystem utility used to print working directory or return working directory name.

Some examples of pwd Command:

pwd

This will print the current working directory.

You can also use pwd command in conjunction with other commands like cd to navigate the file system, for example:

cd /usr/local
pwd

140. qalter Command

qalter Command is a batch utility used to alter batch job

Some examples of qalter Command:

To change the name of a job:

qalter -N new_job_name job_id

To change the queue a job is running in:

qalter -q new_queue_name job_id

To change the number of nodes or processors a job is requesting:

qalter -l nodes=4:ppn=8 job_id

141. qdel Command

qdel Command is a batch utility used to delete batch job.

Some examples of qdel Command:

To delete a single job by specifying its job ID:

qdel 12345

To delete multiple jobs by specifying their job IDs:

qdel 12345 12346 12347

142. qhold Command

qhold Command is a batch utility used to hold batch jobs.

Some examples of qhold Command:

To hold a single job by specifying its job ID:

qhold 12345

To hold multiple jobs by specifying their job IDs:

qhold 12345 12346 12347

143. qmove Command

qmove Command is a batch utility used to move batch job.

Some examples of qmove Command:

To move a single job by specifying its job ID to another queue:

qmove new_queue_name 12345

To move multiple jobs by specifying their job IDs to another queue:

qmove new_queue_name 12345 12346 12347

144. qmsg Command

qmsg Command is a batch utility used to send message across batch jobs.

Some examples of qmsg Command:

To send a message to the user who submitted a single job by specifying its job ID:

qmsg -j 12345 "The job is running smoothly"

To send a message to a specific user:

qmsg -u username "Your job is complete"

145. qrerun Command

qrerun Command is a batch utility used to rerun batch jobs

Some examples of qrerun Command:

To rerun a single job by specifying its job ID:

qrerun 12345

To rerun multiple jobs by specifying their job IDs:

qrerun 12345 12346 12347

To rerun all of the jobs that belong to a specific user:

qrerun -u username

146. qrls Command

qrl Command is a batch utility used to release batch jobs

Some examples of qrls Command:

To release a single job by specifying its job ID:

qrls 12345

To release multiple jobs by specifying their job IDs:

qrls 12345 12346 12347

To release all of the jobs that belong to a specific user:

qrls -u username

147. qselect Command

qselect Command is a batch utility used to select batch jobs

Some examples of qselect Command:

To display all of the jobs that belong to a specific user:

qselect -u username

To display all of the jobs that belong to the current user:

qselect -u $(whoami)

To display all of the jobs that are currently running:

qselect -s R

148. qsig Command

qsig Command is a batch utility used to signal batch jobs

Some examples of qsig Command:

To suspend a single job by specifying its job ID:

qsig -s suspend 12345

To resume a single job by specifying its job ID:

qsig -s resume 12345

To terminate a single job by specifying its job ID:

qsig -s term 12345

149. qstat Command

qstat Command is a batch utility used to show status of batch jobs

Some examples of qstat Command:

To display information about a single job by specifying its job ID:

qstat 12345

To display information about multiple jobs by specifying their job IDs:

qstat 12345 12346 12347

To display information about all of the jobs that belong to a specific user:

qstat -u username

150. qsub Command

qsub Command is a batch utility used to submit batch jobs script.

Some examples of qsub Command:

To submit a job script named “job.sh” to the batch system:

qsub job.sh

To specify the number of processors and the amount of memory required by a job:

qsub -l nodes=1:ppn=8,mem=8gb job.sh

To specify a walltime limit for a job:

qsub -l walltime=24:00:00 job.sh

151. read Command

read Command is a shell Programming, used to read a line from standard input.

Some examples of read Command:

read var – This command reads input from the user and assigns it to the variable var. For example, if the user enters “hello”, the variable var would be set to “hello”.
read -p "Enter your name: " name – This command prompts the user to enter their name, and the input is assigned to the variable name. The -p option is used to display a prompt.
read -a arr – This command reads input and assigns it to an array arr.

152. readlink Command

readlink Command is used to print resolved symbolic links or canonical file names.

Some examples of readlink Command:

readlink file.txt – This command prints the value of the symbolic link file.txt
readlink -f file.txt – This command prints the absolute path of the file or link file.txt, resolving any intermediate symlinks. The -f option is used to resolve the final target of the link.
readlink -e file.txt – This command prints the final target of the symbolic link file.txt and returns true if the file or link exists else false. The -e option is used to check if the link exists or not.

153. readonly Command

readlink Command is used to set the readonly attribute for variables

Some examples of readonly Command:

To make a variable read-only:

$ var="hello"
$ readonly var
$ var="goodbye"
-bash: var: readonly variable

To make a function read-only:

$ function myfunc { echo "hello"; }
$ readonly -f myfunc
$ myfunc() { echo "goodbye"; }
-bash: myfunc: cannot overwrite function

154. renice Command

renice Command is a process Management utility used to set nice values of running processes.

Some examples of renice Command:

To change the priority of a process with a specific PID:

$ renice -n 10 -p 1234

To change the priority of all processes running as a specific user:

$ renice -n 10 -u username

155. return Command

return Command is a shell Programming used to return from a function.

Some examples of return Command:

The following script defines a function myfunc that takes a single argument and returns the square of that argument:

#!/bin/bash

myfunc() {
  local arg=$1
  local result=$((arg * arg))
  return $result
}

myfunc 5
echo "The result is $?"

156. rm Command

rm Command is a filesystem utility, used to remove files or directories.

Some examples of rm Command:

To remove a single file: rm file.txt
To remove multiple files at once: rm file1.txt file2.txt file3.txt
To remove a directory and all of its contents: rm -r my_directory

157. rmdel Command

rmdel Command is a Source Code Control System (SCCS) utility, used to remove a delta from an SCCS file.

The rmdel command in SCCS is used to remove a delta (a set of changes) from the SCCS file. This command can be used to remove a specific version of the file, or to remove a specific set of changes made to the file.

Here is an example of how to use the rmdel command in SCCS:

Some examples of rmdel Command:

rmdel -r2 file.c

158. rmdir Command

rmdir (remove directory) Command is a filesystem utility, used to remove a directory from linux.

Some examples of rmdir Command:

To remove an empty directory: rmdir my_directory
To remove multiple empty directories at once: rmdir my_directory1 my_directory2 my_directory3

159. rsync Command

rsync Command is a fast and versatile command-line utility for synchronizing files and directories between two locations over a remote shell

Some examples of rsync Command:

To copy a file from the local machine to a remote machine: rsync file.txt [email protected]:/path/to/destination
To copy a directory and its contents from the local machine to a remote machine: rsync -avz my_directory [email protected]:/path/to/destination
To copy a file from a remote machine to the local machine: rsync [email protected]:file.txt /path/to/destination

160. sact Command

sact Command is a Source Code Control System (SCCS) utility, used to print current SCCS file-editing activity.

Some examples of sact Command:

sact File

161. sar Command

sar Command is a system administration utility, used for system activity report.

Some examples of sar Command:

Display CPU usage statistics for the current day:

sar

Display memory usage statistics for the current day:

sar -r

162. sccs Command

sccs Command is a Source Code Control Utility (SCCS), used for front end for the SCCS subsystem.

Some examples of sccs Command:

Check out a file for editing:

sccs get file.c

Check in a file after editing:

sccs delta file.c

Show the history of a file:

sccs prs -l file.c

163. sed Command

sed Command is a text processing utility, is a stream editor.

Some examples of sed Command:

Replace the first occurrence of a word in a file:

sed 's/word/replace/' file.txt

Replace all occurrences of a word in a file:

sed 's/word/replace/g' file.txt

Replace the nth occurrence of a word in a line:

sed 's/word/replace/3' file.txt

164. seq Command

seq Command is used to print a sequence of numbers.

Some examples of seq Command:

To generate a sequence of numbers from 1 to 10, enter:

seq 1 10

To generate a sequence of even numbers from 2 to 10, enter:

seq 2 2 10

To generate a sequence of numbers from 10 to 1, with a decrement of 2, enter:

seq 10 -2 1

165. set Command

set Command is a used to set or unset options and positional parameters.

Some examples of set Command:

To set a positional parameter, enter:

set -- arg1 arg2 arg3

This will set the positional parameters to “arg1”, “arg2”, and “arg3”.

To display the current positional parameters, enter:

set

To unset a positional parameter, enter:

set --

166. sh Command

sh Command is a shell programming utility, used to shell, the standard command language interpreter.

Some examples of sh Command:

Run a shell script: sh script.sh
Run a command as a non-root user: sh -c "command"
Run a command with a specific shell: sh -c "command" -s /bin/bash

167. shift Command

shift Command is a shell programming utility, used to shift positional parameters.

Some examples of shift Command:

Shift the positional parameters to the left: shift
Shift the positional parameters to the left by a specific number: shift 2

168. shopt Command

shopt Command is a shell programing utility, used to control optional shell behavior.

Some examples of shopt Command:

Display the current value of an option: shopt -p option_name
Enable an option: shopt -s option_name
Disable an option: shopt -u option_name

169. sleep Command

sleep Command is a shell programming utility, used to suspend execution for an interval.

Some examples of sleep Command:

Sleep for 5 seconds: sleep 5
Sleep for 1 minute: sleep 60
Sleep for 2 hours and 30 minutes: sleep 9000

170. sort Command

sort Command is a text processing utility used to sort, merge, or sequence check text files.

Some examples of sort Command:

Sort a file alphabetically: sort file.txt
Sort a file in reverse order: sort -r file.txt
Sort a file numerically: sort -n file.txt

171. split Command

split Command is used to split files into pieces.

Some examples of split Command:

Split a file into smaller files of 1000 lines each: split -l 1000 file.txt
Split a file into smaller files of 100KB each: split -b 100k file.txt
Split a file into smaller files of 100 lines each and prefix the output files with ‘part’: split -l 100 -d -a 3 file.txt part

172. ss Command

ss command is a linux utility used to displays information in similar fashion to netstat. Note that ss is a little crude compared to netstat.

Some examples of ss Command:

Display all TCP connections: ss -t
Display all UDP connections: ss -u
Display all UNIX domain socket connections: ss -x

173. stress Command

stress Command is a shell programming testing utility, which uses a square-root function to force the CPUs to work hard.

Some examples of stress Command:

Stress the CPU for 60 seconds: stress --cpu 4 --timeout 60s
Stress the memory for 120 seconds: stress --vm 2 --timeout 120s
Stress the I/O for 30 seconds: stress --io 2 --timeout 30s

174. strings Command

strings Command is a C programming utility, used to find printable strings in files.

Some examples of strings Command:

Extract strings from a binary file: strings binary_file
Extract strings of at least 10 characters: strings -n 10 binary_file
Extract strings from a binary file and show the offset of each string: strings -t x binary_file

175. strip Command

strip Command is a C programming utility, used to remove unnecessary information from executable files.

Some examples of strip Command:

Strip all symbols from an object file: strip file.o
Strip only debugging symbols from an object file: strip --strip-debug file.o
Strip all symbols and debugging information from an executable: strip --strip-all file

176. stty Command

stty Command is used to set the options for a terminal.

Some examples of stty Command:

Display the current terminal settings: stty -a
Disable echo on the terminal: stty -echo
Enable echo on the terminal: stty echo

177. suspend Command

suspend Command is a shell programming utility, used to suspend execution of the shell until it receives a continue signal.

Some examples of suspend Command:

Suspend the current shell or terminal session: suspend
Resume the suspended shell or terminal session: fg

178. tabs Command

tabs Command is a linux utility, used to create tabs in terminal.

Some examples of tabs Command:

You can use the following command to set the tab completion to use 8 columns:

echo "set tabsize 8" >> ~/.inputrc

This command will add the line “set tabsize 8” to the file .inputrc in your home directory. This will cause the tab completion to use 8 columns.

Another command tset is used to set terminal modes, including setting the number of columns used for tab completion.

tset -Q -m 'tabs'

179. tail Command

tail Command is a text processing utility, used to copy the last part of a file.

Some examples of tail Command:

Display the last 10 lines of a file:

tail /path/to/file.txt

Display the last 20 lines of a file:

tail -n 20 /path/to/file.txt

Display the last 100 bytes of a file:

tail -c 100 /path/to/file.txt

180. talk Command

talk Command is a linux utility, used to talk to another user.

Some examples of talk Command:

talk

181. tee Command

tee Command is a shell programming utility, used to duplicate standard input.

Some examples of tee Command:

To write the output of the “ls” command to a file named “filelist.txt”, while also displaying the output on the screen, you can use the following command:

ls | tee filelist.txt

To write the output of a command to multiple files at once, you can use the following command:

command | tee file1.txt file2.txt file3.txt

182. test Command

test Command is a Linux shell programming utility, used to evaluate expression, whether it is correct, before deployment.

Some examples of test Command:

Check if a file exists:

test -e /path/to/file

Check if a file is a directory:

test -d /path/to/directory

Check if a file is a regular file (and not a directory or a link):

test -f /path/to/file

183. time Command

time Command is a Linux process management utility, used to time the execution of a simple command.

Some examples of time Command:

time ls -l

This command will display the contents of the current directory in a long format, and also display the time it took for the ls command to run.

Another example:

time sleep 5

184. times Command

times Command is a process management utility, used to write process execution times.

Some examples of times Command:

times

This command will display the accumulated user and system CPU time for the current shell and its child processes.

The output of the command will be in the format:

user time  system time  children's user time  children's system time

185. top Command

top Command is a process management utility, used to show real-time display of running processes.

Some examples of top Command:

top

186. touch Command

touch Command is a filesystem utility, used to create file and Change file access and modification times.

Some examples of touch Command:

touch file.txt

This command will create a new, empty file named “file.txt” in the current directory, or update the timestamp of an existing file with the same name.

Another example:

touch -a file.txt

This command will update the access timestamp of the file named “file.txt”, without modifying the file’s content.

187. tput Command

tput command allows shell scripts to do things like clear the screen, underline text, and center text no matter how wide the screen is.

Some examples of tput Command:

Move the cursor to the x,y position on the screen: tput cup x y
Clear the screen: tput clear
Set the text color: tput setaf color (where color is a number representing the desired color)

188. tr Command

tr (translate) Command is a text processing utility, used to translate characters.

Some examples of tr Command:

Translate all lowercase characters to uppercase: tr a-z A-Z
Delete all occurrences of the letter ‘a’: tr -d a
Squeeze repeating occurrences of the letter ‘a’ into one: tr -s a

189. traceroute Command

traceroute command is used to determine the path between two connections.

Some examples of traceroute Command:

Trace the route to a specific host: traceroute example.com
Use ICMP packets instead of UDP packets: traceroute -I example.com
Set the maximum number of hops: traceroute -m 15 example.com

190. trap Command

trap Command is a process management utility, used to trap signals.

Some examples of trap Command:

Specify a command to be executed when the script exits: trap 'echo "Script exited"' EXIT
Specify a command to be executed when the script receives a INT signal: trap 'echo "Script interrupted"' INT

191. true Command

true Command is a shell programming utility, used to return true value.

Some examples of true Command:

true command is mostly used in shell scripts as a placeholder command, or to ignore the exit status of a previous command.

Example:

#!/bin/bash
# This script will execute command1, even if command2 fails

command2 || true
command1

192. ts Command

ts command is to add timestamps to the beginning of each line of input.

Some examples of ts Command:

ts command is mostly used in combination with other commands like tail or grep to timestamp log files.

Example:

#!/bin/bash
# This script will timestamp the output of the 'ls' command

ls -l | ts

193. tsort Command

tsort Command is a text processing utility, used to topological sort files.

Some examples of tsort Command:

Here are some examples of how to use the tsort command:

Sort a list of ordered pairs: tsort input_file
Sort a list of ordered pairs from standard input: command1 | tsort

The input data must be in the form of ordered pairs, where each line represents an edge in a directed acyclic graph (DAG). The first element of the pair is the ‘to’ vertex, and the second element is the ‘from’ vertex.

Example:

#!/bin/bash
# This script will sort a list of ordered pairs

tsort input_file

194. tty Command

tty Command is used to return user’s terminal name.

Some examples of tty Command:

tty command is mostly used in shell scripts to determine if the current shell is running in a terminal or if a command is being run in a non-interactive shell.

Example:

#!/bin/bash
# This script will print the file name of the terminal

tty

195. type Command

type Command is used to displays how a name would be interpreted if used as a command.

Some examples of type Command:

type command is mostly used in shell scripts to determine how a command is executed and to find the location of a command.

Example:

#!/bin/bash
# This script will display information about a command

type ls

196. ulimit Command

ulimit Command is used to set or report file size limit.

Some examples of ulimit Command:

To check the current open file limit for a user:

ulimit -n

To increase the limit of open file to 4096:

ulimit -n 4096

To check the current stack size limit:

ulimit -s

197. umask Command

umask Command is used to get or set the file mode creation mask.

Some examples of umask Command:

To check the current umask value:

umask

To set the umask value to 077, resulting in newly created files having permissions of 600 (rw——-) and newly created directories having permissions of 700 (rwx——):

umask 077

To set the umask value to 002, resulting in newly created files having permissions of 664 (rw-rw-r–) and newly created directories having permissions of 775 (rwxrwxr-x):

umask 002

198. umount Command

unmount Command is used to unmount a filesystem.

Some examples of umount Command:

To unmount a file system located at /mnt/data:

umount /mnt/data

To unmount a file system by device name /dev/sdb1:

umount /dev/sdb1

To force unmount a busy file system:

umount -l /mnt/data

199. unalias Command

unalias Command is used to remove aliases.

Some examples of unalias Command:

o remove an alias named ‘ll’:

unalias ll

To remove all defined aliases:

unalias -a

200. uname Command

uname Command is used to return system name.

Some examples of uname Command:

To display the kernel version:

uname -r

To display the hostname:

uname -n

To display the processor architecture:

uname -m

201. uncompress Command

uncompress Command is used to uncompress or expand compressed data.

Some examples of uncompress Command:

To decompress a file named “file.txt.Z”:

uncompress file.txt.Z

To decompress multiple files at once:

uncompress file1.txt.Z file2.txt.Z file3.txt.Z

To decompress a file and overwrite the original:

uncompress -f file.txt.Z

202. unexpand Command

unexpand Command is a text processing utility, used to convert spaces to tabs.

Some examples of unexpand Command:

To convert all spaces at the beginning of each line in a file named “file.txt” to tabs:

unexpand file.txt

To convert spaces to tabs with a tab stop of 8 characters:

unexpand -t 8 file.txt

To convert spaces to tabs and also overwrite the original file:

unexpand -a file.txt

203. unget Command

unget Command is a Source Code Command System (SCCS) utility, used to undo a previous get of an SCCS file.

Some examples of unget Command:

an example of how the “unget” command can be used in a C program:

#include <stdio.h>

int main() {
   char c;

   printf("Enter a character: ");
   c = getchar();
   ungetc(c, stdin);
   printf("You entered: ");
   c = getchar();
   printf("%c\n", c);
   
   return 0;
}

204. uniq Command

uniq Command is a text processing utility, used to report or filter out repeated lines in a file.

Some examples of uniq Command:

To remove duplicate lines from a file named “file.txt” and write the output to a new file named “output.txt”:

uniq file.txt output.txt

To display only the duplicate lines in a file named “file.txt”:

uniq -d file.txt

To display only the unique lines in a file named “file.txt”:

uniq -u file.txt

205. unlink Command

unlink Command is a filesystem utility used to call the unlink function.

Some examples of unlink Command:

To remove a file named “file.txt”:

unlink file.txt

To remove a file named “file.txt” and suppress error messages if the file doesn’t exist:

unlink -f file.txt

To remove multiple files at once:

unlink file1.txt file2.txt file3.txt

206. unset Command

unset Command is used to unset values and attributes of variables and functions.

Some examples of unset Command:

To remove a variable named “var”:

unset var

To remove a function named “myfunc”:

unset -f myfunc

To remove multiple variables at once:

unset var1 var2 var3

207. unzip Command

unzip Command is a Linux processing utility, used to unzip files on a terminal.

Some examples of unzip Command:

To extract all files from a ZIP archive called “example.zip” in the current directory, you can use the following command:

unzip example.zip

To extract files from a ZIP archive to a specific directory, use the -d option followed by the directory path:

unzip example.zip -d /path/to/directory

To extract specific files from a ZIP archive, you can specify the file names after the archive name:

unzip example.zip file1.txt file2.txt

208. uptime Command

uptime Command is a Linux command that returns information about how long your system has been running together with the current time, with basic users information.

Some examples of uptime Command:

you can also use other command line utilities like awk or cut to extract specific information from the output of the uptime command.

Example :

$ uptime
 14:26:11 up 13 days,  4:44,  2 users,  load average: 0.00, 0.01, 0.05

209. useradd Command

useradd Command is used to create new user accounts.

Some examples of useradd Command:

To add a new user account called “john” with a default home directory, you can use the command useradd john
To specify a custom home directory for the new user, you can use the -d option, like this: useradd -d /home/john john
To specify a specific user group for the new user, you can use the -g option, like this: useradd -g users john

210. userdel Command

userdel Command is used to delete create users.

Some examples of userdel Command:

It is important to note that if the user is currently logged in, the userdel command will not work. In that case, you can use pkill -KILL -u <username> to forcefully log out the user.

Example :

$ userdel -r john

This command will delete the user account of “john” and also remove its home directory and files.

$ userdel -f john

211. uucp Command

uucp Command is a networking utility used for system-to-system copy.

Some examples of uucp Command:

To copy a file called “file.txt” from the local system to a remote system called “remote”, you can use the command uucp file.txt remote:/path/to/destination
To copy a directory called “mydir” from the remote system “remote” to the local system, you can use the command uucp remote:/path/to/mydir mydir

212. uudecode Command

uudecode Command is a networking utility used to decode a binary files.

Some examples of uudecode Command:

To decode a file called “encoded-file.uu” and save the result as “decoded-file”, you can use the command uudecode encoded-file.uu -o decoded-file
To decode a file called “encoded-file.uu” and save the result in the same location with the same name but with the original file extension, you can use the command uudecode encoded-file.uu

213. uuencode Command

uuencode Command is a networking utility used to encode a binary files.

Some examples of uuencode Command:

To encode a file called “file.bin” and save the result as “encoded-file.uu”, you can use the command uuencode file.bin encoded-file.uu
To specify a different name for the encoded file, you can use the -m option, like this: uuencode file.bin encoded-file.uu -m file.bin

214. uustat Command

uustat Command is a networking utility, used to uucp status inquiry and job control.

Some examples of uustat Command:

To display the status of all files in the UUCP queue, you can use the command uustat
To display the status of a specific file in the UUCP queue, you can specify the file name as an argument, like this: uustat file.txt

215. uux Command

uux Command is a process management utility, used for remote command execution.

Some examples of uux Command:

To execute the command “ls -l” on a remote system called “remote”, you can use the command uux remote!ls -l
To execute a command and redirect the output to a file, you can use the > operator, like this: uux remote!ls -l > remote-ls.txt

216. val Command

val Command is a Source Code Control System (SCCS) utility, used to validate SCCS files.

Some examples of val Command:

To determine if file zas.yesterblog.coder is an SCCS text file, enter:

val -ytext zas.yesterblog.coder

217. vi Command

vi Command is a text processing utility, used for screen-oriented (visual) display editor.

Some examples of vi Command:

To open a file called “example.txt” in the current directory, use the command: vi example.txt
To open a new file called “newfile.txt” in the current directory, use the command: vi newfile.txt
To open a file called “example.txt” in a different directory, use the command: vi /path/to/directory/example.txt

218. w Command

The “w” command in Linux is used to display information about the users currently logged into the system, as well as their processes. The output of the command includes the user’s login name, the tty or terminal they are using, their remote host (if applicable), their login time, the amount of time they have been idle, and the command they are currently running.

Here is an example of the output of the “w” command:

$ w
 23:47:57 up 2 days,  2:55,  2 users,  load average: 0.00, 0.01, 0.05
USER     TTY      FROM             [email protected]   IDLE   JCPU   PCPU WHAT
user1    tty1                      21:01    2days  0.09s  0.09s -bash
user2    pts/0    192.168.1.100    22:35    23:47   0.00s  0.00s w

w Command is used to show who is logged on and what they are doing.

219. wait Command

wait Command is a process management utility, used to await process completion.

Some examples of wait Command:

Using the “wait” command to wait for a background process to complete:

$ command1 &
$ pid=$!
$ command2
$ wait $pid

220. wc Command

wc Command is a text processing utility, used for word, line, and byte or character count

Some examples of wc Command:

Here are some examples of using the “wc” command:

$ wc file.txt

This command will display the number of lines, words, and characters in the file “file.txt”. The output will be in the format: lines, words, characters, filename.

$ echo "hello world" | wc

This command will display the number of lines, words, and characters in the string “hello world”. The output will be in the format: lines, words, characters.

$ wc -l file.txt

221. what Command

what Command is a Source Code Control System (SCCS) utility, used to identify SCCS files

Some examples of what Command:

$ what /usr/bin/ls

This command will display the version of the “ls” command, which is located in the “/usr/bin” directory. The output will be in the format: filename, version.

222. whereis Command

whereis command in Linux is used to locate the binary, source, and manual page files for a command.

Some examples of whereis Command:

$ whereis ls

This command will display the location of the binary, source, and manual page files for the “ls” command. The output will be in the format: command: binary_location source_location manual_location

223. which Command

which command in linux is used to identify the location of executables.

Some examples of which Command:

which ls – Displays the full path of the ‘ls’ command
which java – Displays the full path of the ‘java’ command
which -a nano – Displays all the paths of the ‘nano’ command, if multiple exist

224. who Command

who Command is a system administration utility, used to display who is on the system.

Some examples of who Command:

who – Displays information about all users currently logged into the system
who am i – Displays information about the current user
who -u – Displays information about all users, including those who have logged in and out

225. write Command

write Command is used to write to another user’s terminal.

Some examples of write Command:

write user1 – Sends a message to the user ‘user1’
write user1 tty1 – Sends a message to the user ‘user1’ on terminal ‘tty1’
write user1 < message.txt – Sends the contents of the file ‘message.txt’ as a message to the user ‘user1’

226. xargs Command

xargs Command is a shell programming used to construct argument lists and invoke utility.

Some examples of xargs Command:

ls -l | xargs rm – Lists all files in the current directory, then removes them using rm command
find . -name "*.txt" | xargs grep "keyword" – Search for the keyword in all text files in the current directory and subdirectories
cat file.txt | xargs -n1 command – Take input from a file, split it into single line and pass it as an argument to a command.

227. yacc Command

yacc Command is a C programming utility, and stands for yet another compiler compiler. yacc command converts a context-free grammar specification into a set of tables for a simple automaton that executes an LALR(1) parsing algorithm.

Some examples of yacc Command:

Create a file called “calc.y” and put the following grammar rules in it:

%{
#include <stdio.h>
%}

%token NUM
%left '+' '-'
%left '*' '/'
%right UMINUS

%%

expr : expr '+' expr
    | expr '-' expr
    | expr '*' expr
    | expr '/' expr
    | '-' expr %prec UMINUS
    | NUM
    ;

%%

int yyerror(char *s) {
    printf("error: %s\n", s);
}

int main(void) {
    yyparse();
}

228. zcat Command

zcat Command is a text processing utility, used to expand and concatenate data.

Some examples of zcat Command:

zcat file.txt.gz – Displays the contents of the gzip compressed file ‘file.txt.gz’
zcat file1.txt.gz file2.txt.gz – Displays the contents of multiple gzip compressed files ‘file1.txt.gz’ and ‘file2.txt.gz’
zcat file.txt.gz | less – Displays the contents of the gzip compressed file ‘file.txt.gz’ and pipes it through the less command for better navigation.

229. zip Command

zip Command is used to create zip file from archives, to manage data more easily, and reduce data coruption.

Some examples of zip Command:

zip archive.zip file1.txt – Compress the file ‘file1.txt’ into an archive called ‘archive.zip’
zip -r archive.zip dir1 – Compress the entire directory ‘dir1’ and its contents into an archive called ‘archive.zip’
zip -m archive.zip file1.txt – Compress the file ‘file1.txt’ into an existing archive called ‘archive.zip’ and remove the original file

Linux Command Cheat Sheet (Categories)

Since Linux commands are so many, this cheat sheet, outlines the various types of Linux commands in their categories.

Batch Utilities Commands

Basic Batch Utilities Commands:

qalter Command – Alter batch job
qdel Command – Delete batch jobs
qhold Command – Hold batch jobs
qmove Command – Move batch jobs
qmsg Command – Send message to batch jobs
qrerun Command – Rerun batch jobs
qrls Command – Release batch jobs
qselect Command – Select batch jobs
qsig Command – Signal batch jobs
qstat Command – Show status of batch jobs
qsub Command – Submit a script

C Programming Commands

Basic C Programming Commands:

c99 Command – Compile standard C programs
cflow Command – Generate a C-language flowgraph
ctags Command – Create a tags file
cxref Command – Generate a C-language program cross-reference table
flex Command – Generate programs for lexical tasks
fort77 Command – w:FORTRAN compiler
lex Command – Generate programs for lexical tasks
nm Command – Write the name list of an object file
strings Command – Find printable strings in files
strip Command – Remove unnecessary information from executable files
yacc Command – Yet another compiler compiler

Filesystem Commands

Basic filesystem commands:

basename Command – Return non-directory portion of a pathname
cat Command – Concatenate and print files
cd Command – Change the working directory
chgrp Command – Change the file group ownership
chmod Command – Change the file modes/attributes/permissions
chown Command – Change the file ownership
cksum Command – Write file checksums and sizes
cmp Command – Compare two files
compress Command – Compress data
cp Command – Copy files
dd Command – Convert and copy a file
df Command – Report free disk space
dirname Command – Return the directory portion of a pathname
du Command – Estimate file space usage
file Command – Determine file type
find Command – Find files
link Command – Call link function
ln Command – Link files
ls Command – List directory contents
mkdir Command – Make directories
mkfifo Command – Make FIFO special files
mktemp Command – Create a temporary file or directory
mount Command – Mount a file system
mv Command – Move files
pathchk Command – Check pathnames
pwd Command – print working directory – Return working directory name
rm Command – Remove files or directories
rmdir Command – Remove directories
touch Command – Create file and Change file access and modification times
umount Command – Unmount a filesystem
unlink Command – Call the unlink function

Input/Output information Command

Basic input/output information command:

iostat Command – collect and show operating system storage input and output statistics

Internet Command

Basic internet command:

ftp Command – Internet file transfer program

Network and Networking Commands

Basic networking commands:

uucp Command – System-to-system copy
uudecode Command – Decode a binary file
uuencode Command – Encode a binary file
uustat Command – uucp status inquiry and job control
hostname Command – Show the system’s host name
netstat Command – Displays network information and statistics

Process Management and Processes Commands

Basic process management commands:

apt Command – For installing, updating, removing, and otherwise managing deb packages
at Command – Execute commands at a later time
batch Command – Schedule commands to be executed in a batch queue
bg Command – Run jobs in the background
fg Command – Run jobs in the foreground
fuser Command – List process IDs of all processes that have one or more files open
jobs Command – Display status of jobs in the current session
kill Command – Terminate or signal processes
nice Command – Invoke a utility with an altered nice value
nohup Command – Invoke a utility immune to hangups
pgrep Command – Find processes with the given name using pattern matching
pkill Command – Kills processes with the given name using pattern matching
ps Command – Report process status
pstree Command – Display a tree of processes
renice Command – Set nice values of running processes
time Command – Time a simple command
times Command – Write process times
top Command – Real-time display of running processes
trap Command – Trap signals
uux Command – Remote command execution
wait Command – Await process completion
chroot Command – run a command or interactive shell using a specific directory as the root directory

Programming Command

Basic programming commands:

make Command – Maintain, update, and regenerate groups of programs

Source Code Control System (SCCS) Command

Basic source code control system (sccs) commands:

admin Command – Create and administer SCCS files
delta Command – Make a delta (change) to an SCCS file
get Command – Get a version of an SCCS file
prs Command – Print an SCCS file
rmdel Command – Remove a delta from an SCCS file
sact Command – Print current SCCS file-editing activity
sccs Command – Front end for the SCCS subsystem
unget Command – Undo a previous get of an SCCS file
val Command – Validate SCCS files
what Command – Identify SCCS files

Shell programming

Basic shell programming commands:

bash Command – The Bourne-again shell
shopt Command – Control optional shell behavior
break Command – Exit from for, while, or until loop
continue Command – Continue from for, while, or until loop
dot Command – Execute commands in the current environment
echo Command – Write arguments to standard output
eval Command – Construct command by concatenating arguments
exec Command – Execute commands and open, close, or copy file descriptors
exit Command – Cause the shell to exit
false Command – Return false value
logger Command – Log messages
print Command – Print a file directly without using a Windows application that supports printing
printf Command – Write formatted output
sh Command – Shell, the standard command language interpreter
shift Command – Shift positional parameters
sleep Command – Suspend execution for an interval
suspend Command – Suspend execution of the shell until it receives a continue signal
tee Command – Duplicate standard input
test Command – Evaluate expression
true Command – Return true value
command Command – Execute a simple command
cut Command – Cut out selected fields of each line of a file
expr Command – Evaluate arguments as an expression
getopts Command – Parse utility options
read Command – Read a line from standard input
return Command – Return from a function
xargs Command – Construct argument lists and invoke utility

System and System Administration Commands

Basic system and system administration commands:

passwd Command – Set or change user password
sar Command – System Activity Report
who Command – Display who is on the system

Text Processing and Programming

Basic text processing and programming:

awk Command – Pattern scanning and processing language
diff Command – Compare two files
ed Command – The standard text editor
ex Command – Open text editor
fold Command – Filter for folding lines
gawk Command – Pattern scanning and processing language, GNU’s version of awk
head Command – Copy the first part of files
iconv Command – Codeset conversion
less Command – Display files on a page-by-page basis
more Command – Display files on a page-by-page basis
paste Command – Merge corresponding or subsequent lines of files
patch Command – Apply changes to files
pr Command – Print files
sed Command – Stream editor
tail Command – Copy the last part of a file
tr Command – Translate characters
tsort Command – Topological sort
vi Command – Screen-oriented (visual) display editor
wc Command – Word, line, and byte or character count
asa Command – Interpret carriage-control characters
comm Command – Select or reject lines common to two files
csplit Command – Split files based on context
expand Command – Convert tabs to spaces
join Command – Relational database operator
lp Command – Send files to a printer
nl Command – Line numbering filter
sort Command – Sort, merge, or sequence check text files
unexpand Command – Convert spaces to tabs
uniq Command – Report or filter out repeated lines in a file
zcat Command – Expand and concatenate data
nano Command – Small text editor

Miscellenous (Misc) Commands

Miscellenous (misc) commands:

alias Command – Define or display aliases
ar Command – Create and maintain library archives
bc Command – Arbitrary-precision arithmetic language
cal Command – Print a calendar
crontab Command – Schedule periodic background work
date Command – Write the date and time
env Command – List environment variables or invoke a command in a modified environment
export Command – Set the export attribute for variables
fc Command – Process the command history list
fortune Command – Displays a random quotation
gencat Command – Generate a formatted message catalog
getconf Command – Get configuration values
grep Command – Search text for a pattern
groups Command – List groups a user belongs to
hash Command – Remember or report utility locations
id Command – Return user identity
ipcrm Command – Remove a message queue, semaphore set, or shared memory segment identifier
ipcs Command – Report interprocess communication facilities status
locale Command – Get locale-specific information
localedef Command – Define locale environment
login Command – Begin sessions on a system
logname Command – Return the user’s login name
logout Command – End sessions on a system
m4 Command – Macro processor
mailx Command – Process messages
man Command – Display system documentation
mesg Command – Permit or deny messages
newgrp Command – Change to a new group
od Command – Dump files in various formats
pax Command – Portable archive interchange
readonly Command – Set the readonly attribute for variables
seq Command – Print a sequence of numbers
set Command – Set or unset options and positional parameters
split Command – Split files into pieces
stty Command – Set the options for a terminal
tabs Command – Set terminal tabs
talk Command – Talk to another user
tput Command – Change terminal characteristics
tty Command – Return user’s terminal name
type Command – Displays how a name would be interpreted if used as a command
ulimit Command – Set or report file size limit
umask Command – Get or set the file mode creation mask
unalias Command – Remove alias definitions
uname Command – Return system name
uncompress Command – Expand compressed data
unset Command – Unset values and attributes of variables and functions
write Command – Write to another user’s terminal

Other Commands

Other commands:

datamash Command – performs basic numeric, textual and statistical operations on input textual data files
mtail Command – extract metrics from application logs
parallel Command – execute jobs in parallel (shell utility)
rsync Command – synchronizing files and directories between two locations over a remote shell (command-line utility)
stress Command – square-root function to force the CPUs to work hard
readlink Command – print resolved symbolic links or canonical file names
ts Command – adds a timestamp to the beginning of each line of input
uptime Command – returns information about how long your system has been running together with the current time
history Command – list all commands history used on a system
zip Command – compress file
unzip Command – uncompress file
hostname Command – display the IP address of the remote machine
useradd Command – add user
userdel Command – delete user
clear Command – clear all inputed commands, as if you just logged into terminal
dir Command – computer file and directory listing
groupadd Command – create new group account
groupdel Command – delete existing group account
last Command – show last logged-in user
locate Command – search for directory
ping Command – test ip address accesibility
ss Command – dump socket statistics and displays information
traceroute Command – determine the path between two connections
whereis Command – locate the binary, source, and manual page files for a command
which Command – identify the location of executables
htop Command – monitor server’s processes in real time
dc Command –

200+ Basic Linux Commands listed (alphabetically) with examples:

admin Command
alias Command
apt Command
ar Command
asa Command
at Command
awk Command
basename Command
bash Command
batch Command
bc Command
bg Command
break Command
c99 Command
cal Command
cat Command
cd Command
cflow Command
chgrp Command
chmod Command
chown Command
chroot Command
cksum Command
clear Command
cmp Command
comm Command
command Command
compress Command
continue Command
cp Command
crontab Command
csplit Command
ctags Command
cut Command
cxref Command
datamash Command
date Command
dc Command
dd Command
delta Command
df Command
diff Command
dir Command
dirname Command
dot Command
du Command
echo Command
ed Command
env Command
eval Command
ex Command
exec Command
exit Command
expand Command
export Command
expr Command
false Command
fc Command
fg Command
file Command
find Command
flex Command
fold Command
fort77 Command
fortune Command
ftp Command
fuser Command
gawk Command
gencat Command
get Command
getconf Command
getopts Command
grep Command
groupadd Command
groupdel Command
groups Command
hash Command
head Command
history Command
hostname Command
htop Command
iconv Command
id Command
iostat Command
ipcrm Command
ipcs Command
jobs Command
join Command
kill Command
last Command
less Command
lex Command
link Command
ln Command
locale Command
localedef Command
locate Command
logger Command
login Command
logname Command
logout Command
lp Command
ls Command
m4 Command
mailx Command
make Command
man Command
mesg Command
mkdir Command
mkfifo Command
mktemp Command
more Command
mount Command
mtail Command
mv Command
nano Command
netstat Command
newgrp Command
nice Command
nl Command
nm Command
nohup Command
od Command
parallel Command
passwd Command
paste Command
patch Command
pathchk Command
pax Command
pgrep Command
ping Command
pkill Command
pr Command
print Command
printf Command
prs Command
ps Command
pstree Command
pwd Command
qalter Command
qdel Command
qhold Command
qmove Command
qmsg Command
qrerun Command
qrls Command
qselect Command
qsig Command
qstat Command
qsub Command
read Command
readlink Command
readonly Command
renice Command
return Command
rm Command
rmdel Command
rmdir Command
rsync Command
sact Command
sar Command
sccs Command
sed Command
seq Command
set Command
sh Command
shift Command
shopt Command
sleep Command
sort Command
split Command
ss Command
stress Command
strings Command
strip Command
stty Command
suspend Command
tabs Command
tail Command
talk Command
tee Command
test Command
time Command
times Command
top Command
touch Command
tput Command
tr Command
traceroute Command
trap Command
true Command
ts Command
tsort Command
tty Command
type Command
ulimit Command
umask Command
umount Command
unalias Command
uname Command
uncompress Command
unexpand Command
unget Command
uniq Command
unlink Command
unset Command
unzip Command
uptime Command
useradd Command
userdel Command
uucp Command
uudecode Command
uuencode Command
uustat Command
uux Command
val Command
vi Command
w Command
wait Command
wc Command
what Command
whereis Command
which Command
who Command
write Command
xargs Command
yacc Command
zcat Command
zip Command

References

Linux/Basic commands – Wikiversity