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Linux Interview Questions

Linux Interview Questions: During the job interview, when an interviewee is able to answer the Linux interview questions descriptively, his or her destiny gets decided instantly. Answering actually to Linux, interview questions build up scope for various opportunities for a flourishing interview attempt. This article contains Linux interview questionnaire. The article has been build up by Aptron's Linux specialists, Linux experts, and Linux trainers who have put genuine efforts and best of facts while preparing Linux interview questions and answers for freshers, and skilled professionals. The questionnaire comprises of detailed answers casing basic and advanced Linux interview questions. The questionnaire assists job aspirants to crack interviews and acknowledge relevant answers to their doubts or puzzlements. The Linux Interview Questions is a summarization of verticals available in the Linux technology.

linux interview questions

About Linux

Linux was first developed for personal computers, but it has been harbored to more platforms than any other operating system. Linux is the foremost operating system on servers and mainframe computers, and TOP500 supercomputers. It is also used in desktop computers. Linux also runs on embedded systems, i.e. devices such as routers, video game consoles, automation controls, televisions, digital video recorders and smart watches. Many smartphones and tablet computers run Android and other Linux imitative. The dominance of Android on smartphones, Linux has the chief installed base of all general-purpose operating systems.

Linux Interview Questions And Answers

1. What is Linux?

Linux is an operating system, which is based on Linux Kernel. It is an open-source operating system where it can run on different hardware platforms. It provides a free and low-cost operating system for users. It is a user-friendly environment where they can easily modify and create variations in the source code.

2. What is the difference between UNIX and LINUX?

Unix originally began as a propriety operating system from Bell Laboratories, which later on spawned into different commercial versions. On the other hand, Linux is free, open source and intended as a non-propriety operating system for the masses.

3. What is the core of the Linux operating system?

Kernel is the core for Linux operating system.

4. Who invented Linux?

Linus Torvalds created Linux.

5. What is the Linux Kernel? Is it legal to edit Linux Kernel?

Kernel is the heart of the operating system. It acts as a bridge between software and hardware. If Software requests the hardware, then kernel delivers the data between software and hardware. For example, if you want to play a song you should launch your default player, it requests the kernel to play a song, now kernel will contact the hardware to seek the permissions or to seek the hardware components like if you plugged in any headset to the device. Most of the Android phones use Linux kernels.

Yes, the kernel can edit, because it is released under General Public License.

6. Explain the history of Linux?

Linus Torvalds was a student at the University of Helsinki, Finland in 1991. He started writing code on his own to get the academic version of Unix for free. Later on, it became popular as Linux Kernel.

7. What is a swap space?

Swap space is a certain amount of space used by Linux to temporarily hold some programs that are running concurrently. This happens when RAM does not have enough memory to hold all programs that are executing.

8. What is Shell?

Shell is a computer program which acts as an interface between the user and the kernel. User can communicate with the kernel by writing programs, commands and scripts on the shell. It accepts human-readable commands and converts them into the kernel understandable language.

9. How many types of Shells are there in Linux?

They are five Shells in Linux:

  • C Shell (csh): It is like C syntax and provides spelling checking and job control.
  • Korn Shell (ksh): Is a high-level programming language shell.
  • Z Shell (Zsh): It provides some unique nature like it observes login/logout watching, file name generating, startup files, closing comments.
  • Bourne Again Shell (bash): It is the default to Linux distributions.
  • Friendly Interactive Shell (Fish): It provides web-based configuration, auto-suggestions, etc.

10. What are the basic components of Linux?

Basic components of Linux

  1. Kernel: It is the core component of the Linux, it acts as an interface between software and hardware.
  2. Shell: It acts as an interface between the user and the Kernel.
  3. GUI: It stands for Graphic User Interface, which is another way for the user to interact with the system. But it is unlike images, buttons, text boxes for interaction.
  4. System Utilities: These are the software functions that allow users to manage the computer.
  5. Application Programs: Set of functions designed to perform a set of tasks.

11. What Are Pipes?

A pipe is a chain of processes so that output of one process (stdout) is fed an input (stdin) to another. UNIX shell has a special syntax for creation of pipelines. The commands are written in sequence separated by |. Different filters are used for Pipes like AWK, GREP.

e.g. sort file | lpr ( sort the file and send it to printer)

12. What Does Nslookup Do? Explain Its Two Modes.

Nslookup is used to find details related to a Domain name server. Details like IP addresses of a machine, MX records, servers etc. It sends a domain name query packet to the corresponding DNS.

Nslookup has two modes. Interactive and non interactive. Interactive mode allows the user to interact by querying information about different hosts and domains.

Non interactive mode is used to fetch information about the specified host or domain.

Interactive mode:

Nslookup [options] [server]

13. What Is Bash Shell?

Bash is a free shell for UNIX. It is the default shell for most UNIX systems. It has a combination of the C and Korn shell features. Bash shell is not portable. any Bash-specific feature will not function on a system using the Bourne shell or one of its replacements, unless bash is installed as a secondary shell and the script begins with #!/bin/bash. It supports regular and expressions. When bash script starts, it executes commands of different scripts.

14. What Are The Process States In Linux?

Process states in Linux:

Running: Process is either running or ready to run.
Interruptible: a Blocked state of a process and waiting for an event or signal from another process.
Uninterruptible:- a blocked state. Process waits for a hardware condition and cannot handle any signal.
Stopped: Process is stopped or halted and can be restarted by some other process.
Zombie: process terminated, but information is still there in the process table.

15. What Is A Zombie?

Zombie is a process state when the child dies before the parent process. In this case the structural information of the process is still in the process table. Since this process is not alive, it cannot react to signals. Zombie state can finish when the parent dies. All resources of the zombie state process are cleared by the kernel.

16. Explain Each System Calls Used For Process Management In Linux.

System calls used for Process management:

Fork () :- Used to create a new process
Exec() :- Execute a new program
Wait():- wait until the process finishes execution
Exit():- Exit from the process
Getpid():- get the unique process id of the process
Getppid():- get the parent process unique id
Nice():- to bias the existing property of process

17. Name some Linux variants.

Some of the Linux commands are:

  • CentOS
  • Ubuntu
  • Redhat
  • Debian
  • Fedora

18. What is the basic difference between BASH and DOS?

  • BASH commands are case sensitive while DOS commands are not case sensitive.
  • DOS follows a convention in naming files. In DOS, 8 character file name is followed by a dot and 3 characters for the extension. BASH doesn't follow such convention.

19. What is a root account?

The root account is like a system administrator account. It provides you full control of the system. You can create and maintain user accounts, assign different permission for each account, etc.

20. What is CLI?

CLI stands for Command Line Interface. It is an interface that allows users to type declarative commands to instruct the computer to perform operations.

21. What are the basic commands for user management?

  • last,
  • chage,
  • chsh,
  • lsof,
  • chown,
  • chmod,
  • useradd,
  • userdel,
  • newusers etc.

22. What is LILO?

LILO stands for LInux LOader. LILO is a Linux Boot Loader that loads Linux Operating System into the main memory to begin execution. Most of the computers come with boot loaders for certain versions of Windows or Mac OS. So, when you want to use Linux OS, you need to install a special boot loader for it. LILO is one such boot loader.

When the computer is started, BIOS conducts some initial tests and transfers control to the Master Boot Record. From here, LILO loads the Linux OS and starts it.

The advantage of using LILO is that it allows fast boot of Linux OS.

23. What are inode and process id?

inode is the unique name given by the operating system to each file. Similarly, process id is the unique id given to each process.

24. What is Virtual Desktop?

Virtual Desktop is a feature that allows users to use the desktop beyond the physical limits of the screen. Basically, Virtual Desktop creates a virtual screen to expand the limitation of the normal screen.

There are two ways Virtual Desktop can be implemented:

  1. Switching Desktops
  2. Oversized Desktops

Switching Desktops

In the case of Switching Desktops, you can create discrete virtual desktops to run programs. Here, each virtual desktop will behave as an individual desktop and the programs running on each of these desktops is accessible only to the users who are using that particular desktop.

Oversized Desktops

Oversized Desktops do not offer a discrete virtual desktop but it allows the user to pan and scroll around the desktop that is larger in size than the physical screen.

25. What are daemons?

A daemon is a computer program that runs as a background process to provide functions that might not be available in the base Operating System. Daemons are usually used to run services in the background without directly being in control of interactive users. The purpose of Daemons are to handle periodic requests and then forward the requests to appropriate programs for execution.

26. What is a Latch?

A Latch is a temporary storage device controlled by timing signal which can either store 0 or 1. A Latch has two stable states (high-output or 1, and low-output or 0) and is mainly used to store state information. A Latch can store one bit of data as long as it is powered on.

27. What are hard links?

Hard links point directly to the physical file on disk, and not on the pathname. This means that if you rename or move the original file, the link will not break since the link is for the file itself, not the path where the file is located.

28. What is the maximum length for a filename under Linux?

Any filename can have a maximum of 255 characters. This limit does not include the path name, so therefore the entire pathname and filename could well exceed 255 characters.

29. How does case sensitivity affect the way you use commands?

When we talk about case sensitivity, commands are considered identical only if every character is encoded as is, including lowercase and uppercase letters. This means that CD, cd, and Cd are three different commands. Entering a command using uppercase letters, where it should be in lowercase, will produce different outputs.

30. What are environmental variables?

Environmental variables are global settings that control the shell's function as well as that of other Linux programs. Another common term for environmental variables is global shell variables.

31. Explain how to color the Git console?

To color the Git console, you can use the command git config—global color.ui auto. In the command, the color.ui variable sets the default value for a variable such as color.diff and color.grep.

32. How can you append one file to another in Linux?

To append one file to another in Linux you can use command cat file2 >> file 1. The operator >> appends the output of the named file or creates the file if it is not created. While another command cat file 1 file 2 > file 3 appends two or more files to one.

33. Explain how you can find a file using Terminal?

To find a file you have to use a command, find . –name "process.txt" . It will look for the current directory for a file called process.txt.

34. Explain how you can create a folder using Terminal?

To create a folder, you have to use command mkdir. It will be something like these: ~$ mkdir Guru99

35. Explain how you can view the text file using Terminal?

To view the text file, go to the specific folder where the text files are located by using the command cd and then type less filename.txt.

36. Explain how to enable curl on Ubuntu LAMP stack?

To enable curl on Ubuntu, first, install libcurl, once done use following command sudo/etc/init .d /apache2 restart or sudo service apache2 restart.

Career scopes and salary scale

The average being without a job is growing across job markets. Nevertheless, when it is concerning Linux development and Linux programming, the requirement of Linux professionals are at higher side. Linux contenders having in-depth knowledge and skill-based training in Linux are able realize their smooth ways to accomplish their career goals. Besides, Linux has occupied the highest place in the arena of cloud services. A Linux applicant is expected a minimum salary of 40, 000 dollars per annum. However, the salary of an knowledgeable Linux expert can reach to double. The salaries are very dependent upon the location, business, and the company’s requirements.


The article ‘Linux interview questions’ has been efficiently answered every advanced Linux interview questions. As well, the thoughtful planned of the Linux interview questions for experienced is being premeditated by our trainers and team of experts. They have tried their top of data to aid professionals in getting answers to all doubts and not clear concepts. Even then, if students still require more detailing about Linux, then they may drop in a message to our experts regarding Linux interview questions for experienced professionals. Our trainers would be happy to assist and resolve all your Linux programming issues of the students. Join Linux Training in Noida, Linux Training in Delhi, Linux Training in Gurgaon

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