Linux Interview Questions

linux interview questions

People get scared by hearing the word “interview” because of the tough questions that interviewers ask you in order to judge your skills and expertise. However, with the help of our Linux interview questions, we have made it easier for you to crack these interviews easily and step into the world of job. Our expert teams and professionals come up with interesting questions and answer that interviewers ask you in your interview and help you in answering those questions with confidence.

About Linux

Linux is a UNIX operating system that was first introduced in the market by Linus Torvalds. Based on Linux Kernel, this operating system can run on various hardware platforms for commercial or personal purposes. Mascot, which is basically a penguin-shaped figure named Tux, is another prominent element of Linux. If you are willing to pursue your career in the field of Linux, then you must be highly skilled and talented to go through the process of interviews and crack it with the help of our Linux Interview questions and answers.

Best Linux Interview Questions of 2020

Q1) What is Linux?

Ans: 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.

Q2) What is the difference between Linux and Unix?

Ans: Diffrences between Linux and Unix

Linux

Unix

Both paid and free distributions are available.

Different paid structures for different levels of Unix.

Linux primarily uses GUI with an optional command line interface

Unix uses command line interface

Linux OS is portable and can be executed in different hard drives

Unix OS is not portable.

Linux is developed by a worldwide Linux community.

Unix is developed by AT&T developers.

Linux is free. And it is download through intenet under GNU licenses.

Most Unix Like Operating Systems are not free.

Linux is used at home based pc’s, phones, etc.

Unix is used in server systems.

And some other difference's.

Linux is a Unix clone But if you consider Portable Operating System Interface (POSIX) standards then Linux can be considered as UNIX.

Linux Is Just KernalAll Linux distributions include GUI system, GNU utilities, installation & management tools, GNU c/c++ Compilers, Editors (vi), and various applications like OpenOffice, Firefox.

UNIX operating systems are considered as a complete OS as everything come from a single vendor.

Security And Firewall

Linux comes with open source Netfilter and IPTables based firewall tool to protect your server and desktop from the crackers and hackers. UNIX operating systems comes with its own firewall products. 

Backup And Recovery UNIX and Linux come with their own set of tools for backing up data to tape and other backup media. However, both Linux and UNIX share some common tools such as tar, dump/restore, and cpio etc.

Q3) What is the core of the Linux operating system?

Ans: Kernel is the core for Linux operating system.

Q4) Who invented Linux?

Ans: Linus Torvalds created Linux.

Q5) What is the Linux Kernel?  Is it legal to edit Linux Kernel?

Ans: 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.

Q6) Explain the history of Linux?

Ans: Linux 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.

Q7) 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.

Q8) How many types of Shells are there in Linux? 

Ans: 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. 

Q9) What are the basic components of Linux?

Ans: Basic components of Linux

  1. Kernel: It is the core component of the Linux, it acts as an interface between Software and hardware.
  2.   
  3. Shell: It acts as an interface between the user and the Kernel.
  4. 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.
  5. System Utilities: These are the software functions that allow users to manage the computer.
  6. Application Programs: Set of functions designed to perform a set of tasks.

Q10) How do you open a command prompt when issuing a command?

Ans: Launch your terminal by pressing CTRL+ALT+T or by giving terminal in the menu search bar.

Q11) What is BASH? 

Ans: Bash is a Unix shell and command processor written by Brian Fox for the GNU project. It is free software and acts as a replacement for Bourne Shell. It is an interpreted and not compiled process which can also be run in the terminal window. This allows users to write commands and cause actions. Bash is capable of reading commands from shell scripts.

Q12) What is LILO? 

Ans: LILO means Linux Loader is a boot loader which is used for the Linux operating system. Most of the Linux Operating systems use LILO, to boot the operating system into main memory to start the operations. 

Q13) What is a swap space? 

Ans: Swap Space is used when then physical Ram memory is running out. It will move the Ram inactive pages to the swap space. It can consider in the form of a dedicated swap partition or a swap files.

Q14) What is CLI?

Ans: CLI means Command language Interpreter. It interacts with the computer program, where the user issues command in the form of text lines. It Interacts with the computer terminals also, the interface accepts the text lines and convert them as a command to the operating system.

Q15) What is the GUI?

GUI means Graphical User Interface. It is a human-computer interface that uses windows, images, icons and menus which can be manipulated by using a mouse. Most of the modern applications in electronic gadgets communicate with the user through GUI. GUI is a combination of graphical and textual interaction that uses buttons, menus, message boxes, etc.

Q16) Explain File Permissions types in Linux?

Ans: Each file or directory has 3 permissions

They are

 
  1. Read--It refers that only they can read the file.
  2. Write--It refers that they can write the file or modify the file of a directory.
  3. Execute-- It affects the user’s capability to execute the file or to view the file of a directory.

Q17) What are the environmental variables?

They are dynamic values which affect the process of programs on a computer. They exist in every operating system and their types may vary. They can be created, edited, saved and deleted and they also give the information about the system behaviour.

Q18) What is the advantage of Open Source?

Ans: Linux was one of the first open source technologies, many programmers added software that completely open to the users, which means you can download the file and change the code as you like. It has a wide range of options to the users and increased security.

Q19) What is the disadvantage of Open Source?

Ans: Disadvantages of Open Source Operating System mentioned below

  1. Difficulty of use 
  2. Compatibility Issues
  3. Liabilities and warranties
  4. Hidden costs

Q20) What are the symbolic links?

Ans: It will be redirected to another file using its path. Target files do not contain any data. Symbolic links redirect to another entry somewhere in the file system. If the target file is deleted, link to that file is removed, but not the file.

Q21) What are hard links?

Ans: A hard link is an another name for an existing file on Linux. We can create so many number of hard links, for any file. They can create links for other hard links.

Q22) What is redirection?

Ans: Redirection can be defined as changing the standard input and output devices. To redirect metacharacters are used, you can redirect the file or program. 

Q23) What are Daemons?

Ans: A Daemons is a background process which accepts the requests for service from other computers, most of the operating systems use daemons in other forms. 

Q24) Describe the root account?

Ans: Root is the user name, that default have access to all files and commands. The root user can do many things, but an ordinary user cannot do like installing software, change file permissions, etc.

Q25) Explain virtual desktop?

Ans: Virtual Desktop is a user interface when you are facing the problem of how to manage multiple windows on your desktop, virtual desktop serves as an alternative. Virtual desktop stores remote server and allow you to use one or more programs on a clean slate.

Q26) What are the different modes when using the v editor?

Ans: There are three kinds of modes in vi editor. They are

 

  • Command Mode/ Regular Mode
  • Insertion Mode/Edit Mode.
  • Ex Mode/ Replacement Mode.
  •  

Q27) What are inode and process id?

Ans:  inode is a unique name given to each file and process id is a unique name given to each process. 

Q28) What are the Process states in Linux?

Ans: Five process states in Linux. They are

  1. New/ Ready: A new process is created and ready to run.
  2. Running: The process is being executed.
  3. Blocked/ Wait: The process is waiting for input from the user. 
  4. Terminated/ Completed: The process completed the execution or terminated by the operating system. 
  5. Zombie: The process is deleted, but still the information regarding the process exists in the process table.

Q29) Explain Process Management System Calls in Linux?

Ans: The process management system calls in Linux:

  • fork(): Used to create a new process.
  • exec(): Execute new process.
  • wait(): wait until process execution.
  • exit(): exit from the process.
  • System calls to get the Process id :
  • getpid(): to find the unique process id. 
  • getppid(): to find the unique parent process id.
  •  

Q30) Explain File Permission groups in Linux?

Ans: There are three user based permission groups for each file and directory.

They are:

  1. Owner: Owners only will have to access the file or directory, they will not impact the actions of other users.
  2. Group: These permissions apply only to the group, that has been assigned to the file or directory. They will not impact the actions of other users.
  3. All Users: These permissions are applied to all users on the system.
Career scopes and salary scale

Network engineers are known to build and design effective computer networking systems and alternatives. They are also responsible to install software applications that usually make the connections between the organizational services with the client machines at a faster rate. In the world of digitalization, the scope of job opportunities in the field of networking has increased in recent years. Jobs such as network engineering posts is something that you should be looking into.

A fresher in the field of networking is offered about 35,000 to 45,000 dollars per annum, while the experienced ones are offered with a hike of 30 percent and above, depending on their previous withdrawn salary. An experienced candidate can withdraw up to 114,000 to 125,000 dollars per annum based on the skills and expertise he or she has.

Conclusion

This article focuses on providing almost all types of information related to the Networking Interviewing Questions and answers that will help you in cracking all the interviews that you give with ease. It will also enhance the quality of your knowledge database. If your questions are unanswered, feel free to mention them in the comments section. Our expert will look into it and address it immediately with the appropriate answer.

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