[2023] Top 50 Linux Command Interview Questions and Answers

Here's a list of 50 common Linux commands interview questions along with their answers to help you prepare for your Linux-related job interview:

1. What command is used to display the current working directory in Linux?

Answer: The pwd command is used to display the present working directory in Linux.

2. How do you list the files and directories in a directory using the command line?

Answer: The ls command is used to list the files and directories in the current directory. Adding options like -l provides a detailed view.

3. What is the command to create a new directory in Linux?

Answer: The mkdir command is used to create a new directory. For example, mkdir new_directory.

4. How can you remove a file using the command line?

Answer: The rm command is used to remove files. For example, rm file.txt.

5. Explain the purpose of the cp command in Linux.

Answer: The cp command is used to copy files or directories. For instance, cp file.txt new_location.

6. What command is used to move files or directories in Linux?

Answer: The mv command is used to move files or directories from one location to another. For example, mv file.txt new_location.

7. How can you navigate to the home directory using the command line?

Answer: The cd command without any arguments will take you to the home directory. For example, cd.

8. Explain the function of the touch command in Linux.

Answer: The touch command is used to create an empty file or update the timestamp of an existing file. For instance, touch new_file.txt.

9. How can you view the contents of a text file in the command line?

Answer: The cat command displays the entire contents of a text file. For example, cat file.txt.

10. What is the purpose of the grep command in Linux?

Answer: The grep command is used to search for text patterns within files. For instance, grep pattern file.txt.

11. How can you view the contents of a text file with pagination in the command line?

Answer: The less command displays the contents of a file with pagination, allowing you to scroll through the content. For example, less file.txt.

12. Explain the chmod command in Linux and how it is used.

Answer: The chmod command is used to change the permissions of files and directories. For example, chmod 755 file.txt gives read, write, and execute permissions to the owner and read and execute permissions to others.

13. What command is used to display system information and resource usage?

Answer: The top command displays real-time system information, including resource usage of processes.

14. How can you search for a specific command in the history using the command line?

Answer: The history command shows the list of executed commands. You can use grep to search for a specific command. For example, history | grep command.

15. Explain the purpose of the df command in Linux.

Answer: The df command is used to display information about disk space usage on file systems.

16. How can you view the manual pages of a command in the command line?

Answer: The man command followed by the command name displays the manual pages with detailed information. For example, man ls.

17. What is the command to shut down or reboot the system?

Answer: The shutdown command with appropriate options is used to shut down or reboot the system. For example, shutdown -h now shuts down the system immediately.

18. How can you view the IP addresses assigned to network interfaces using the command line?

Answer: The ifconfig command displays the IP addresses assigned to network interfaces.

19. Explain the ps command in Linux and how it is used.

Answer: The ps command shows information about currently running processes. For example, ps aux displays detailed information about all processes.

20. How can you terminate a running process using the command line?

Answer: The kill command is used to terminate processes by their Process ID (PID). For example, kill PID.

21. What is the command to compress files or directories in Linux?

Answer: The tar command is used to compress files and directories into a single archive. For instance, tar -czvf archive.tar.gz files.

22. How can you extract files from a compressed archive in Linux?

Answer: The tar command with appropriate options is used to extract files from a compressed archive. For example, tar -xzvf archive.tar.gz.

23. Explain the purpose of the find command in Linux.

Answer: The find command is used to search for files and directories based on various criteria. For instance, find /path/to/search -name filename.

24. How can you connect to a remote server using the command line?

Answer: The ssh command is used to establish secure shell connections to remote servers. For example, ssh username@hostname.

25. What command is used to display the list of logged-in users in Linux?

Answer: The who command shows the list of users currently logged in to the system.

26. Explain the purpose of the du command in Linux.

Answer: The du command displays the disk space used by files and directories. For example, du -sh directory provides a summary of space used by the directory.

27. How can you display the content of a file in reverse order using the command line?

Answer: The tac command displays the content of a file in reverse order. For instance, tac file.txt.

28. What is the command to edit a text file using the command line?

Answer: The nano or vi command is used to edit text files from the command line.

29. How can you display the last lines of a text file using the command line?

Answer: The tail command displays the last lines of a text file. For example, tail -n 10 file.txt displays the last 10 lines.

30. Explain the chown command in Linux and how it is used.

Answer: The chown command is used to change the ownership of files and directories. For instance, chown user:group file.txt.

31. What is the purpose of the echo command in Linux?

Answer: The echo command is used to print text to the terminal or redirect it to files.

32. How can you set environment variables using the command line?

Answer: The export command followed by the variable name and value is used to set environment variables. For example, export VAR=value.

33. Explain the function of the uptime command in Linux.

Answer: The uptime command displays the system's uptime and load average.

34. What is the command to change the password of a user account in Linux?

Answer: The passwd command is used to change the password of a user account. For instance, passwd username.

35. How can you rename a file using the command line?

Answer: The mv command is used to rename files. For example, mv old_name new_name.

36. Explain the purpose of the wget command in Linux.

Answer: The wget command is used to download files from the web using the command line.

37. What is the command to list all running services on a Linux system?

Answer: The systemctl command with appropriate options is used to list all running services. For example, systemctl list-units --type=service.

38. How can you create a symbolic link to a file using the command line?

Answer: The ln command with the -s option is used to create symbolic links. For instance, ln -s target_file link_name.

39. Explain the grep command's -r option and its significance.

Answer: The grep -r option searches for a text pattern recursively in all files and directories within a specified directory.

40. What is the purpose of the alias command in Linux?

Answer: The alias command is used to create aliases for frequently used commands, making them shorter or more convenient.

41. How can you display the current date and time using the command line?

Answer: The date command displays the current date and time.

42. What is the command to compress a file using gzip compression?

Answer: The gzip command is used to compress files using gzip compression. For instance, gzip file.txt.

43. How can you count the number of lines, words, and characters in a text file using the command line?

Answer: The wc command provides word, line, and character count for a text file. For example, wc file.txt.

44. Explain the function of the dd command in Linux.

Answer: The dd command is used for low-level copying and conversion of files. It can be used for tasks like creating disk images.

45. How can you display the contents of a compressed file without extracting it?

Answer: The zcat command displays the contents of a compressed file without extracting it. For instance, zcat file.txt.gz.

46. What is the command to list all environment variables in Linux?

Answer: The printenv command lists all environment variables.

47. How can you find and replace text in a file using the command line?

Answer: The sed command is used to find and replace text in files. For example, sed 's/old_text/new_text/g' file.txt.

48. Explain the purpose of the clear command in Linux.

Answer: The clear command is used to clear the terminal screen, providing a clean workspace.

49. How can you display the permissions of a file using the command line?

Answer: The ls command with the -l option displays the permissions of files and directories in long format.

50. What is the purpose of the killall command in Linux?

Answer: The killall command is used to terminate processes by their names rather than their Process IDs (PIDs).

These Linux commands interview questions and answers cover a wide range of essential commands and concepts. Customize your responses based on your experience and the specific requirements of the role you're interviewing for.