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Top 30 Linux Interview Questions and Answers
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Top 30 Linux Interview Questions and Answers
If you are a practitioner with Linux skills and want to get a dedicated job opportunity, you are at the right place. Here, in this amazing article, you will read the Top 30 Linux Interview Questions and Answers prepared by professionals for your preparation for the interview.
Moreover, in the end, we have also mentioned a reputed training institute offering a dedicated training & certification program for IT Aspirants related to Linux Enterprise. What are we waiting for? Let’s get straight to the point!
What is Linux?
Linux is a popular open-source operating system for desktops, servers, and embedded devices that is based on Unix. It is renowned for being flexible, secure, and stable. Ubuntu and CentOS are two examples of Linux distributions that offer distinct user experiences.
Let’s move on to the Top 30 Linux Interview Questions and Answers, clearing your doubts related to the Interview!
Top 30 Linux Interview Questions and Answers
1. What is Linux, and how does it differ from UNIX?
UNIX is a family of proprietary operating systems, whereas Linux is a free and open-source operating system kernel (the heart of an OS). Although Linux was influenced by UNIX, it is not UNIX.
2. Explain the Linux file system hierarchy.
Beginning with the root directory (/), the Linux file system hierarchy arranges files and directories in a tree-like structure. Different subdirectories have distinct functions, such as holding system files, user data, and configuration files.
3. What is the root user in Linux?
In Linux, the root user is the superuser with total authority over the system and the ability to take any action.
4. How do you check the Linux version and kernel version?
In the following ways, you can check the Linux distribution version and kernel version using these commands:
- For distribution version:
- lsb_release -a (The majority of distributions can use this command.)
- cat /etc/os-release (This displays more thorough distribution information.)
- hostnamectl (The OS and other system data are also displayed by this command.)
- For kernel version:
- uname -r (The most popular and straightforward method is this one.)
- uname -a (This displays additional kernel information, such as architecture and other specifics.)
- cat /proc/version (The kernel version and build details are also shown here.)
5. What are the different modes in Linux (e.g., single-user mode, multi-user mode)?
The following are the different modes in Linux:
- Runlevel 0: Halt,
- Runlevel 1: Single-user mode,
- Runlevel 2: Multi-user mode (without networking),
- Runlevel 3: Multi-user mode (with networking),
- Runlevel 4: (Unused),
- Runlevel 5: Multi-user mode (with graphical login), and
- Runlevel 6: Reboot.
6. How do you create, delete, and copy files and directories in Linux?
In Linux, you can use mkdir to create directories, rm, and rmdir to delete files and directories (or rm -r for directories containing content), cp and cp -r to copy files and directories and touch or redirect output to create files.
7. What is the difference between rm and rmdir commands?
While rmdir is used to remove empty directories, rm is used to remove files and directories, including those that contain other files and directories.
8. How do you find a file in Linux using the find command?
Starting from a specified directory, the find command looks for files and directories in Linux based on several parameters, including name, type, size, and modification time.
9. Explain the purpose of chmod, chown, and chgrp commands.
The following are the purposes of the mentioned commands:
- chmod: Modifies a file or directory’s read, write, and execute permissions.
- chown: Modifies a file or directory’s owner.
- chgrp: Modifies the group that is linked to a directory or file.
10. What are symbolic links, and how do you create them?
The ln -s command is used to create symbolic links, which are files that serve as pointers to other files or directories.
11. How do you check running processes in Linux?
You can check running processes in Linux via the following commands:
- ps,
- top,
- htop,
- pgrep, and
- pidof.
12. What is the difference between kill and kill -9?
Kill-9 sends a KILL signal, which ends the program immediately, whereas kill sends a TERM signal, which permits the program to end gracefully.
13. How do you run a process in the background?
The command you wish to execute should have an ampersand (&) at the end.
14. Explain the PS command and its options.
The options of the ps command determine which processes are displayed and the output format (e.g., ps aux for a user-friendly view of all processes, ps -ef for full details). The ps command shows information about running processes.
15. What is a daemon process in Linux?
A daemon process is a background operation that frequently carries out system-level tasks without requiring direct user input.
16. How do you check network interfaces and IP addresses in Linux?
To verify network interfaces and IP addresses, use the ipa or ifconfig command.
17. What is the purpose of the netstat command?
Although it is now mostly replaced by ss, netstat shows network connections, listening ports, and network interface statistics.
18. How do you test connectivity between two servers using ping?
To verify basic network connectivity to another server, use the command ping <hostname or IP address>.
19. Explain the use of ssh and scp commands.
While scp enables safe file transfers between systems via SSH, ssh enables secure remote login to another system.
20. How do you configure a static IP address in Linux?
Depending on the distribution, setting the desired IP, subnet mask, gateway, and DNS servers requires modifying network configuration files (e.g., /etc/network/interfaces or /etc/sysconfig/network-scripts/) to configure a static IP address in Linux.
21. What is a shell script, and how do you execute it?
Making a text file executable (chmod +x script.sh) and then running it (e.g.,./script.sh or bash script.sh) will run a shell script, which is a text file with a set of commands that the shell performs.
22. How do you use grep to search for text in files?
grep “pattern” filename looks for lines in the given file that contain the word “pattern.”
Explain the difference between > and >> in Linux.
Whereas >> appends to the file, > overwrites it.
23. What is the purpose of cron and crontab?
Crontab is the command used to control the schedule of those tasks for specific users, while cron is the system service that executes scheduled tasks.
24. How do you use awk and sed for text processing?
Sed is a stream editor for text transformation and filtering, and Awk is a powerful language for pattern scanning and text processing.
25. How do you check disk usage in Linux?
To see how much disk space is being used, use the df command.
26. What is the purpose of the /etc/passwd and /etc/shadow files?
/etc/passwd contains fundamental user account information, whereas /etc/shadow holds the encrypted passwords and other security-related details for those accounts.
27. How do you add a new user and assign permissions in Linux?
Use useradd to create a user, and usermod -aG to add them to a group (which grants permissions).
28. Explain the difference between yum and apt package managers.
Yum is mainly utilized on RPM-based distributions, such as Red Hat and CentOS, whereas apt is employed on Debian-based distributions, including Ubuntu and Debian, for the installation, updating, and management of software packages.
29. How do you troubleshoot a system that is running out of disk space?
Troubleshooting low disk space requires identifying large files and directories with du, deleting unnecessary files, and possibly resizing partitions or increasing storage capacity.
Conclusion
Now that you have read the Top 30 Linux Interview Questions and Answers mentioned above, you might be feeling a bit confident about cracking the interviews. Other than that, beginners who have just entered the IT Industry and want to learn Linux Skills can search for a reputed training institute.
For that, you can join a dedicated training & certification program for Linux, “Linux Essential Training Course in Delhi,” offered by Craw Security. During the sessions, students will find themselves among various professionals performing tasks on Linux Operating Systems on the premises of Craw Security.
With that, online sessions will benefit students with the facility of remote learning. After the completion of the Linux Essential Training Course in Delhi offered by Craw Security, students will receive a certificate validating their honed knowledge & skills during the sessions. What are you waiting for? Contact, Now!