30 Commands Frequently Used in Linux

Linux is a powerful operating system that provides a wide range of command-line tools to manage the system. Linux commands are the primary way to interact with the operating system and perform tasks ranging from file management to system administration. In this article, we will discuss 30 Linux commands frequently used in Linux.

Basic Linux Commands

1. cd

The cd command is used to change the current working directory. When you open a terminal, you are in the home directory by default. You can use the cd command followed by the directory path to move to a different directory. For example, to move to the /var/log directory, you can use the command:

cd /var/log

2. ls

The ls command lists the files and directories in the current working directory. By default, the ls command displays only the file names. To display additional information, such as file size and permissions, you can use the -l option. For example, to list the files and directories in the current directory with additional information, you can use the command:

ls -l

3. pwd

The pwd command is used to print the current working directory. This command can be helpful when you need to know your current directory path.

4. mkdir

The mkdir command is used to create a new directory. To create a directory named test, you can use the command:

mkdir test

5. rmdir

The rmdir command is used to remove an empty directory. To remove a directory named test, you can use the command:

rmdir test

6. rm

The rm command is used to remove files and directories. To remove a file named test.txt, you can use the command rm test.txt. To remove a directory and its contents, you can use the -r option. For example, to remove a directory named test and its contents, you can use the command:

rm -r test

7. cat

The cat command is used to display the contents of a file. To display the contents of a file named test.txt, you can use the command

cat test.txt

8. touch

The touch command is used to create a new empty file. To create a file named test.txt, you can use the command:

touch test.txt

9. echo

The echo command is used to print text to the terminal. To print the text Hello World!, you can use the command

echo "Hello World!"

Intermediate Linux Commands

10. grep

The grep command is used to search for text within files. To search for the word test in a file named test.txt, you can use the command:

grep "test" test.txt

To search for text in multiple files, you can use the -r option. For example, to search for the word test in all files in the current directory and its subdirectories, you can use the command:

grep -r "test" .

11. find

The find command is used to search for files and directories based on criteria such as name, size, and permissions. To find all files named test.txt in the current directory and its subdirectories, you can use the command:

find . -name "test.txt"

To find all files larger than 1MB in the current directory and its subdirectories, you can use the command:

find . -size +1M

12. tar

The tar command is used to create and extract archives. An archive is a file that contains other files and directories. To create a new archive named test.tar containing the files in the current directory, you can use the command:

tar -cvf test.tar

To extract an archive named test.tar, you can use the command:

tar -xvf test.tar

13. zip

The zip command is used to compress and decompress files and directories. To create a new zip file named test.zip containing the files in the current directory, you can use the command:

zip -r test.zip .

To extract a zip file named test.zip, you can use the command:

unzip test.zip

14. scp

The scp command securely copies files between remote and local systems. To copy a file named test.txt from a remote system with IP address 192.168.1.1 to the local system, you can use the command:

scp user@192.168.1.1:/path/to/test.txt /local/path

15. ssh

The ssh command is used to connect to remote systems over a secure network. To connect to a remote system with IP address 192.168.1.1, you can use the command

ssh user@192.168.1.1

16. ps

The ps command is used to display information about the running processes. By default, the ps command displays the processes running in the current shell. To show all running processes, you can use the command:

ps -ef

17. top

The top command is used to display real-time information about the system processes and resource usage. This command can be useful when you need to identify processes that are using too much CPU or memory.

top

18. ifconfig

The ifconfig command is used to display network interface information. This command can be helpful when you need to know the IP address of a system or troubleshoot network issues.

19. netstat

The netstat command is used to display information about network connections, routing tables, and network interface statistics. This command can be useful when you need to troubleshoot network issues or monitor network activity.

20. ping

The ping command tests network connectivity by sending ICMP packets to a remote system. To ping a remote system with IP address 192.168.1.1, you can use the command:

ping 192.168.1.1

21. dig

The dig command is used to query DNS servers to retrieve information about domain names. To retrieve the IP address of the domain google.com, you can use the command

dig google.com

22. curl

The curl command transfers data to or from a server using different protocols such as HTTP, FTP, and SMTP. To download a file from a remote server, you can use the command.

curl -O <http://example.com/file.txt>

Advanced Linux Commands

23. awk

The awk command is used to manipulate and process text files. This command can be used to extract data, transform data, and generate reports. To print the second column of a file named test.txt, you can use the command

awk '{print $2}' test.txt

24. sed

The sed command is used to perform text editing operations on files. This command can be used to search for patterns, replace text, and perform other text processing tasks. To replace the word **test**with the word example in a file named test.txt, you can use the command

sed 's/test/example/g' test.txt

25. grep with Regular Expressions

The grep command can be used with regular expressions to perform advanced text searching. Regular expressions are patterns that can match different types of text such as numbers, letters, and symbols. To search for all lines in a file named test.txt that contain a number, you can use the command

grep '[0-9]' test.txt

26. find with Execution

The find command can be used with the -exec option to perform actions on the files or directories that match the search criteria. To delete all files named test.txt in the current directory and its subdirectories, you can use the command

find . -name "test.txt" -exec rm {} \\;

27. tar with Compression

The tar command can be used with compression options to create compressed archives. Compressed archives are smaller in size than regular archives and can be useful when transferring files over a network. To create a compressed archive named test.tar.gz containing the files in the current directory, you can use the command

tar -czvf test.tar.gz .

28. ssh with Port Forwarding

The ssh command can be used with port forwarding options to establish secure connections to remote systems and forward traffic to local ports. To forward traffic from port 8080 on the local system to port 80 on a remote system with IP address 192.168.1.1, you can use the command

ssh -L 8080:localhost:80 user@192.168.1.1

29. iptables

The iptables command is used to manage the firewall rules on Linux systems. This command can allow or block traffic to specific ports or IP addresses. To allow traffic to port 80 on a Linux system, you can use the command

iptables -A INPUT -p tcp --dport 80 -j ACCEPT

30. crontab

The crontab command is used to schedule and automate tasks on Linux systems. This command can run scripts or commands at specific times or intervals. To schedule a script named backup.sh to run every day at 2 AM, you can use the command:

Enter crontab configuration file:

crontab -e

Write on the end of the file the following:

0 2 * * * /path/to/backup.sh

For more crontab configurations, we recommend checking crontab.guru.

Conclusion

In this article, we have discussed 30 Linux commands that are frequently used in Linux. These commands range from basic file management commands such as cd, ls, and mkdir to advanced commands such as awk, sed, and iptables. By mastering these commands, you can manage and administer Linux systems more efficiently.

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