Top 32 Linux Interview Questions and Answers

Every technology era brings new developments and breakthroughs, and Linux is no exception. Linux is one of the several operating systems including Apple’s macOS and Microsoft’s Windows that developers and programmers use. Landing a job in this field usually comprises answering technical questions and tackling a coding problem or completing a take-home project.  

So in this article, we will be looking at multiple Linux interview questions and answers which will help you prepare for the interview.

What is Linux?

Linux is a Unix-like, open-source operating system developed by Linus Torvalds in 1991. Giving users its features, such as security based on authentication and access control, application support, and customizable keywords.

Who Should Consider These Questions?

• Engineers
• Developers
• System Administrators
• IT students specializing in Linux

Top 32 Linux Interview Questions and Answers

The following is a list of 32 Linux interview questions that might help you to crack interview.

1. What are the basic components of Linux?

Linux’s architecture contains four main components: kernel, shell, system utility, and applications.

• Kernel: The kernel is the core part of the Linux OS that is responsible for operations and communication between hardware and software.
• Shell: The shell is an environment in which the Linux operator runs commands, programs, and shell scripts. It is the interface between the user and kernel and is used to execute commands.
• System utility: These are software functions that allow the user to manage the computer.
• Applications: These are software programs designed to accomplish particular tasks.

2. What is LILO ans BASH?

LILO stands for Linux Loader, which is a boot loader used for the Linux operating system. Most Linux OS use LILO as a master or secondary program to boot the operating system into central memory to perform functions.

BASH stands for Bourne Again Shell, which is a command language interpreter that is similar to and interchangeable with Bourne Shell. BASH has some extra features and is the default user shell on many Linux installations. It can also read commands from shell scripts.

3. What are shells used in Linux?

Linux supports multiple shells, each designed for a particular purpose. Some common examples include the following:

• bash (Bourne Again Shell): This is the default shell of most Linux systems.
• zsh (Z Shell): Default shell for Kali Linux and macOS
• ksh (Korn Shell): High-level programming language shell
• Csh (C Shell): Borrows from C programming language
• tcsh (Tenex Shell): This is a command-line shell based on the C Shell.

4. How do you optimize Linux system performance?

You can optimize the Linux performance through several strategies to improve resource usage and efficiency. So some of the strategies are:

• Updates the system as per the latest one available.
• Optimize the disk, enable the caching, and optimize the access pattern.
• Manage memory and CPU usage.
• Disable the unnecessary services and use lightweight alternatives of the tools.
• Monitor the system resources regularly.
• Perform the Kernel parameter tune-up.
• Use tools like Performance Co-Pilot (PCP) to monitor system-level performance.

5. How do you troubleshoot network connectivity issues in Linux?

There are multiple ways to troubleshoot the network connectivity and find the issue suitably:

Check the Internet Connectivity:

First of all, please check if the internet connection option is on and also check the cables to find if there is any issue with it.

Ping test:

Use the ping command to test whether or not your network stack is working. 

Verify the Network Configuration:

• Please check that your network is configured correctly and the network interface has your IP address. You can check it by running the ip addr or ifconfig commands.
• You can also run the ip route command to check if the default gateway is set properly.
• Finally, verify the DNS server configuration in the /etc/resolv.conf file.

Check the Firewall:

Sometimes, firewall rules block the internet connection for the system’s security.

Hence, you can run the ufw or iptables command to modify the firewall rules.

Also Read: Configure a Linux Firewall: Three Approaches

Network Interface:

You can restart your network interface through the ifup and ifdown commands. Once you restart the network interface, please reboot the system to make changes successful.

6. How do you create a user account?

You can use adduser and useradd commands to create a user for the system.

useradd Command:

Let’s create a username, “Ron,” and provide a password for accessing the system:

useradd Ron

passwd Ron

You can also explore the useradd command’s additional options to modify the new user’s permissions and privileges.

adduser Command:

The adduser command is similar to the useradd command, so let’s create a username “Ali”:

adduser Ali

passwd Ali

7. What is the difference between a process and a thread in Linux?

Processes and threads are both significant components of multitasking in Linux, but they perform different functions. Processes are independent programs with their own memory space and resources, meaning each process is isolated from other processes. Thus, they offer a high level of security. 

Threads, on the other hand, are units of execution that exist within a process. All threads within a process share the same resources. Multiple threads can be executed simultaneously, making them useful for tasks requiring cooperation and concurrency. 

8. Do you know the Maximum length (in bytes) of the filename in Linux?

The maximum length of a filename is 255 bytes. In this filename, the pathname is not included, so the total length of the pathname and filename may easily surpass 255 characters.

9. How do you list all the processes running in Linux?

You can list the currently running process in Linux through various commands such as:

ps Command:

The ps command displays brief information about the running processes. You can use the ps -f or ps -f command because the -f option shows the full-format result, and the -e option displays all processes. Furthermore, you can use the ps auxf command to get a detailed list of processes.

top and htop Command:

• The top command displays the real-time details about the system process and the complete resource usage.
• The htop command is the improved version of the top command because it displays the color-coded list with bonus features such as sorting, filtering, sorting, etc.

10.       What is Docker, and how is it useful for Linux administrators?

Docker is a containerization platform that allows Linux administrators to encapsulate applications and their dependencies into containers. This fosters consistency in deployment across different environments. Docker streamlines resource utilization, enhances scalability, and simplifies application management, making it a valuable tool for Linux administrators.

Also Read: 8 Best Docker Containers for Home Servers in 2025

11.       How do you check disk space usage?

There are some simple commands you can use to check disk space usage, such as:

df Command:

The df or disk-free command shows the used and the available disk space. You can use the additional options to check disk space differently. For instance, you can use the df -h command to check the disk usage in the human-readable format.

du Command:

The du or disk usage command estimates and shows the disk space usage, so running the du command with no option shows the disk usage of your current directory. However, you can run the following command to check the disk usage of a specific directory:

du -sh ~/<directory>

ncdu Command:

The NCurses Disk Usage, or ncdu command, displays more interactive disk usage. Similar to the du command, the ncdu command also requires the path of the specific directory to check its space.

12.       What is the rsync command, and how do you use this command for synchronization?

The rsync command is used to synchronize and transfer the files in Linux. It synchronizes files between two local systems, directories, or a network. The basic rsync command contains the following:

rsync <options> <source> <destination>

For example, let’s synchronize between Documents and the Downloads directory. For this, you need to run the following command:

rsync -av ~/Documents ~/Downloads

If you want to go one step further, then you can use the below command:

rsync -avz –delete ~/Documents ~/Downloads

In the above command:

• The -a option preserves all the permissions and other attributes
• The -v option displays the detailed output of the synchronization
• The -z allows compression that decreases the bandwidth use.
• The –delete option removes the file in the Downloads that do not exist in the Documents directory.

13.       List out some Linux distributors?

We have a lot of Linux distributors, so we’ll go through a few of the more significant ones.

Linux Mint: It is a stable and reliable operating system. Mate and Cinnamon are two of the most popular desktop environments used in Linux Mint.

Debian: It is a Linux distribution that stands for stability, reliability, and a well-oiled release process.

Manjaro: It provides a pleasurable experience for both novice and seasoned users.

Ubuntu: Ubuntu is based on Debian and is available in desktop and server variants.

openSUSE: It is a fantastic choice for both novice and experienced users.

Also Read: Setup to Install Linux Mint: A Step-by-Step Guide

14.       How do you format a disk in Linux?

The mkfs or make file system command helps format the disk in the Linux system. All you need to do is use the following method to format the disk:

First, run the lsblk command to list the available partitions and identify which disk you want to format.

If the selected disk is mounted, then unmount it through the following command:

umount <partition>

Now, find the file system type of the disk, like EXT4, NTFS, or XFS. Once you are done then, run one of the following commands according to the file system type:

mkfs.ext4 <partition>

mkfs.xfs <partition>

mkfs.ntfs <partition>

Lastly, mount the disk again through the mount command after the successful format. Moreover, please ensure that you have created a complete disk backup to eliminate the chances of data loss.

15.       How do you change the password for a user account?

Changing the password of a user account is simple because all you need to do is use the passwd command:

passwd username

For example, let’s change the password of a user “Ali” through the below command:

passwd Ali

Once you run the command, the system will ask you to enter and confirm the new password.

16.       How do you secure a Linux server?

There are multiple methods to secure the Linux server and protect it from data breaches, security threats, and unauthorized access. Here are some of these methods:

• Create a strong password
• Update the server and apply security patches.
• Use secured protocols like SSH and configure it to use key-based authentication for higher security.
• Use the intrusion detection system (IDS) to monitor network traffic and prevent malicious activities.
• Configure the firewall to limit the inbound and outbound traffic on the server.
• Disable all unused network services.
• Create regular backups.
• Review logs and perform regular security audits.
• Encrypt network traffic and enable monitoring.

Also Read: Remote Linux Server Access from Windows: Using PuTTY, CMD, GitBash and MobaXterm

17.       What do you understand about process scheduling in Linux?

Process scheduling is the mechanism that identifies the order of processes running on the system. In other words, process scheduling determines the order and execution time of multiple processes running on the system concurrently. This process scheduler of Linux is priority-based and uses a preemptive algorithm. It allots CPU time for different processes to ensure efficient CPU resource usage. These processes are dynamic, and their order can change depending on many factors, such as resource usage, process behavior, and scheduling policies.

18.       What are the most important Linux commands?

There are a ton of useful commands in Linux, and here are some of the commonly used commands:

• ls: Display directory contents such as folders and files.
• mkdir: Used to create a new directory.
• pwd: Shows the current directory.
• top: Display system running processes and resource usage.
• grep: Search a specific pattern in a file.
• cat: Through this command, users can add multiple files and also display the content of the files.
• tar: Archives directories and files into a tarball.
• wget: Download files from the browser or web.
• free: Shows memory usage.
• df: Shows disk space usage.
• man: Gives a manual page for a specific command that displays instructions and details.

19.       How do you troubleshoot a Linux OS that fails to boot?

In case of the system boot failure, you can follow various approaches such as:

• Check the warning and error messages you get during the boot process because it can help you diagnose the issues.
• Check the boot logs to find the exact reason behind the boot error.
• Open the GRUB bootloader and check the boot options to solve the booting problems.
• Check the hardware connections like cables, RAM, cooling fan, etc.
• If the system shows an error message related to the Kernel, try to boot it with the older Kernel version from GRUB.
• Identify the last changes you made in the system before the boot.

20.       How do you compress and decompress files in Linux?

To compress files in Linux, you can use the tar command along with gzip compression.

For example: If we want to create a file name “jayesh” with gzip compression. We use the following command.

tar -czvf jayesh.tar.gz files

This command will create a compressed archive file containg the specified “files”

To decompress the same, we use the following command.

tar -xzvf jayesh.tar.gz

21.       What is the purpose of the SSH protocol in Linux, and how do you securely connect to a remote server using SSH?

The Secure Shell (SSH) is a protocol in Linux which is used to establish a secure encrypted connection between a local and remote machine. It allows to securely access and manage remote servers. If we want to connect to a remote server using SSH. We can use the following command.

ssh username@remote_ip

Here replace the `username` with the desired username of the remote server and replace the `remote_ip` with the IP address of the remote server.

22.       What is the purpose of the ping command in Linux, and how do you test network connectivity to a remote host?

Ping command is used to test the network connectively between the local and remote hosts. It basically sends an ICMP echo request packet to the remote host and waits for the corresponding echo reply packet.

For example: If we want to check the connectivity to a remote host, we use the following command.

ping remote_host_ip

Here replace `remote_host_ip` with the Ip address of the host

23.       How do you configure a DNS server in Linux?

DNS server configuration involves editing the ‘/etc/named.conf’ (BIND) or ‘/etc/named/named.conf.options’ (ISC BIND) file to specify the server’s zone information, name resolution options, and defining forwarders or root hints.

Also Read: 4 Linux Distributions That Feel Most Like Windows in 2025

24.       What is the significance of different runlevels in Linux?

Linux runlevels determine the state a system is operating in. Different runlevels correspond to specific configurations. Some of these include Halt (system shutdown), Single-user mode (maintenance mode), and various multi-user modes. 

There are various reasons to change the runlevel of your Linux system. For example, the single-user mode is great for system maintenance and troubleshooting. Multi-user modes without networking offer excellent security, and some modes support a graphical interface for a more user-friendly experience. 

25.       Explain what shell scripts are and how they’re used in Linux?

A shell script is a plain text file that contains a series of commands. These are executed by a command-line interpreter and can be used for everything from automating tasks and streamlining workflows to installing software and configuring your system. 

26.       Explain how you would find the five largest files in a directory and all its subdirectories?

You can use the find and du commands alongside the sort and head commands to find the largest five files in a directory and its subdirectories. For example, you might use the following code: 

find /path/to/directory -type f -exec du -h {} + | sort -rh | head -n 5

27.       What is an inode? Which fields are stored in an inode?

An inode is a data structure that stores metadata about a file or directory in compatible file systems. Inodes store an array of information important for managing and accessing information efficiently. They have the following fields:  

• File mode, which specifies the file type and permissions
• Owner and group
• File size
• Timestamps
• Links count, the number of hard links pointing to the inode
• Blocks, which store pointers to data blocks within the file
• File system identifier, identifying the filesystem containing the inode
• File generation number
• File ACLs, which store access control lists for user permissions
• Extended attributes, additional metadata about the file

Linux inodes are essential for file system efficiency and contribute to file ownership, timestamps, and permissions, among other things.

28.       How do you configure Linux as a DHCP server for dynamically assigning IP addresses to machines on a LAN?

• Install DHCP server: `sudo apt-get install isc-dhcp-server` (for Ubuntu/Debian)
• Configure DHCP settings in `/etc/dhcp/dhcpd.conf`
• Specify network interface in `/etc/default/isc-dhcp-server`
• Restart DHCP server: `sudo service isc-dhcp-server restart`

29.       What is Swap Space?

Swap Space is the extra space utilized by Linux to temporarily keep simultaneously running processes when RAM space is insufficient. When you start a program, it is stored in RAM so that the CPU can quickly retrieve data. If you have more running programs than RAM can accommodate, the Swap Space is used to store these programs. The processor will now search the RAM and Swap Space for data.

Swap Space is used in the form of an extension of RAM by Linux.

30.       What command would you use to find out how much memory Linux is using?

The following are the commands that you can use:

• vmstat
• htop
• top
• free-m

31.       How to view the list of mounted devices on Linux?

You can view the list of mounted devices on Linux by running the command given below:

 $ mount –l

32.       What is the latest version of Linux?

The Latest version of Linux is the Linux Mint 21.3 “Virginia.” It was released on January 12, 2024, as the LTS (Long Term Support) release. Linux Mint is one of the most popular distributions that provides the desktop computing experience. We can select the pre-installed software applications, including web browsers, office suites, multimedia players, and system utilities, due to which it is considered as user-friendly. 

Summing-Up

We hope these Linux command interview questions will help you prepare for your dream job interview and land worthwhile job opportunities in this field. To become an efficient Linux developer, you can opt for several online courses too.

With these questions, you can exhibit to the interviewer what you know about Linux. As a developer or programmer, expect to clearly and accurately explain the systems and processes you work with.