Linux Interview Questions

Are you looking for a good career through Linux administration? It is great to have a quick review of Linux interview questions that would help you grab complex interviews from any organization. Linux is one of the operating systems commonly used by most organizations for a long time. Linux is an open-source, customized operating system. In the current era of living, we see many new technologies and improvements coming up. Linux is one of the platforms that help organizations achieve their success within a shorter time span. Let us have a quick review of the Linux interview questions that are curated by the experts in the Linux training.

 Categories of Linux Interview Questions

Q1) What do you know about LINUX and elucidate the differences between Unix and Linux? 

Ans: Linux is referred to as one of the most common and popular operating systems that are designed with the Linux Kernel. The Linux operating system is an open-source operating system that is capable of running on multiple platforms. The primary focus of this operating system is to provide the users with a less expensive operating system and free operating system to utilize while working within the organization for multiple projects. The Linux Operating system is also called a user-friendly operating system. It provides the flexibility to users to modify things easily and enables the user to perform the creation of variations within the source code. 

Below are the significant differences between Linux and Unix: LINUX operating system is portable while the Unix operating system is not portable. LINUX operating system is an open-source operating system that is free of cost, and the users from the internet can download it by making use of the GNU license. In contrast, the Unix operating system is not free of cost. LINUX operating system makes use of the which also includes a command-line interface which is an optional thing. The Unix operating system controls only the command-line interface.

Q2) Briefly explain the different permission types available in Linux? 

Ans: There are three permission types that are available in Linux for each file or directory. They are: 

Read: This file permission type is used for reading the file. 

Write: This file permission type is used for writing the fine or for performing any modification to the file of a directory. 

Execute: This file permission is used to execute the file, which will affect the user's capability and view the directory's file.

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Q3) Can you explain why Linux is more secure than any other operating system? 

Ans: Linux is more secure because of the following reasons: 

  • Linux is flexible and incompatible with providing the Limited default privileges to the users that will help in the restriction to the lower levels. Just in case if there is any file attack, then it will only affect the local files and folders and will save from the system-wide damage. 
  • Linux is also referred to as a powerful auditing system that will maintain the logs. 
  • Linux has enhanced features of IPtables that will help in maintaining security at a greater level. 

Q4) What do you know about CLI and BASH? 

Ans:

CLI: CLI refers to a command-line interpreter used for interacting between the different computer programs. It is usually represented in the form of text format. It is also responsible for allowing the users to add the text lines, which can be further converted into user-defined commands. 

BASH: BASH  is referred to as a Unix command, which is written by Brian Fox. Bash is also referred to as free software that is also the replacement for The Bourne shell. BASH allows the users to write the command and perform the related actions, even allowing the users to read the commands that are written in the form of Shell Scripts.

Q5) Briefly explain the features of the Linux operating system? 

Ans: There are different features available in the Linux operating system. They are explained below: 

Portable: LINUX operating system is designed in such a way that it can work on multiple types of hardware. The data is allowed to be carried in the pen drives and memory cards, allowing it to be included in the probability feature. 

Open source: The Linux operating system is a free, open-source operating system that is based on the community development project. 

Multiprogramming: LINUX operating system provides the feature of multiprogramming, allowing users to run multiple programs at the same time. 

Multi-user: the applications are allowed to be created and used by multiple users. In Linux, various users can use their RAM and run the programs at the same time. 

Security: Linux is flexible to provide data security by using the different forms of security policies or security features like authorization, authentication, and encryption.

Q6) What is meant by Linux kernel? 

Ans: Linux Kernel is referred to as a low-level system software with the primary responsibility of managing the user's resources. Linux Kernel is also responsible for providing an interface or a bridge for user-level interaction.

Q7) What do you know about LILO? 

Ans: LILO refers to Linux loader. Linux loader is referred to as the bootloader for Linux. The bootloader's primary responsibility for Linux is to mainly load the Linux operating system into the main memory so that it can start working on the operations.

Q8) Explain briefly about GUI? 

Ans: GUI refers to a graphical user interface that uses the images and Icon so that users can click and navigate checkout to communicate with the machine or a computer. The graphical elements make it easier to interact with the system instead of using the different commands and type the commands, which is more challenging for a human to remember.GUI will also improve the attraction through the icons, color, and images bringing up a good view.

Linux Tutorials

Q9) Give a brief idea about the Linux directory commands? 

Ans: Below is the list of commands of the Linux directory. 

pwd: This command is used for a print working directory. It is referred to as a built-in command that displays the current working location and the working path along with the full path of the directory. 

Is: This command is used for listing the files in the directory folder. 

cd: command is used for change directory, which is used for changing the directory from the present directory to the directory that you want to work. 

mkdir: This command is used for creating a new directory. 

rmdir: This Command is used explicitly for removing the directory from the system.

Q10) Briefly explain the cat command in Linux? 

Ans: The cat command in Linux is used for concatenating and printing the files. Users use this command to check the contents of the dependencies file and confirm the version of the application that they are built already locally.

Linux Technical Interview Questions

Q11) What do you know about PIPE in Linux? 

Ans: A pipe in Linux is referred to as a form of redirection in Linux. The PIPE is specifically used for combining more than two commands, and the output of one command will be taken as input for the next command. 

Syntax: 

command_1 | command_2 | command_3 |command_4 | .... | command_N

Q12) Give a brief idea about the Chmod command? 

Ans: The Chmod command is responsible for changing the file permissions and directory permissions. The Chmod consists of three different types of permissions called to read, write, and execute. They are represented in numbers as below: 

4- read permission 

2- write permission 

1- execute permission

Q13) What are the different commands that are used to exit from VI editors? 

Ans: Two different commands can be used for getting the exit from the VI editors. 

wq: This command is used for exiting from the VI editor by saving the current work that you have done. 

q! : This command is used to exiting from the VI editor without saving the work you have done.

Q14) List different types of modes that are available when you are using the vi editor? 

Ans: There are three different modes of vi editors. They are: 

1. Insertion mode or edit mode 

2. Command mode or regular mode 

3. Ex mode or replacement mode 

Q15) Briefly give an idea about the env command in Linux? 

Ans: The env command is referred to as a shell command that is used explicitly for printing the list of environment variables that run another process in another environment without performing any modifications of changes to the current environment. 

Syntax: env [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]

Q16) Is there a possibility to append one file to another file in Linux? 

Ans: Yes, there is a possibility to append one file to another file in Linux. The command that is used to append from one file to another file is cat file 2 >> file 1. The operator >> in the command is used for appending the output of the named file and is also capable of creating the file if there is no file already created. The other command that is stated below is also used to append two or more files to one. Command: cat file 1 > file 2 > file 3

Q17) What are the different ports that are used for SMTP, FTP, DHCP, SSH, and Squid? What are the commands that are used to check the ports that are there listening in the Linux server?

Ans: Below are the port numbers that are used for these services. 

1. DNS - 53 

2. SMTP - 25 

3. DHCP - 68 

4. FTP - 20 

5. SSH - 22 

6. Squid - 3128

The two commands that are used for checking if the 4th and listening in the Linux server are: 

netstat -l 

netstat --listen

Q18) What are environment variables? 

Ans: Environment variables are referred to as the global settings that will help control the cell's function and the other Linux programs. The environment variables are also called the Global shell variables.

Q19) List out the basic components of the Linux architecture? 

Ans: Below is a list of the basic components of the light next architecture. 

Kernel: Kernel is referred to as one of the most essential core components in the Linux operating system. It is referred to as an interface or a bridge between the software and hardware components. 

Shell: Shell in Linux is also referred to as an interface between the parallel operating system and the users. 

GUI: GUI refers to the graphical user interface used to establish the interaction with the system. 

System Utilities: The system utilities are referred to as a software function responsible for allowing the users to manage the computer. 

Application programs: Application programs here refer to the set of tasks that are specifically designed to perform the set of tasks or operations. 

Q20) Give a brief idea about swap space? 

Ans: The swap space is referred to as a space that is allocated and used when we need actually to run the physical memory. Describe space is responsible for helping users move the inactive pages in their RAM to the swap space. The swap space is available in two different forms called partitions and swap files. 

Linux Interview Questions For Experienced

Q21) What do you know about Hard links? 

Ans: The hard links are used to directly point to the physical file on the desk but not on the pathname. Let us take an example and think that if you move the original file or remove the same, there will be no breaking of hard links as the link itself is used as a file, not the pathname, where the file will be stored in the directory.

Q22) Does the Control + alt + delete key combination work on Linux? 

Ans: Yes, the Control + alt + delete combination works on Linux, and it can be perfectly used to restart the system.

Q23) Briefly describe daemons? 

Ans: Daemons are usually referred to as a kind of service that will offer the different functionalities which we cannot find under the basic operating system. It includes the main tasks like listening for a service request and then performing an action on these requests. Once the service is completed, it will disconnect itself and wait for the next request that will be coming up.

Q24) Know about inode and process ID? 

Ans: The inode is referred to as a unique name given to any file or directory. The process ID is referred to as a unique name given to each process that is created.

Q25) Briefly give an idea about zombies? 

Ans: Zombie is referred to the process state in which the child dies before the parent process dies. In this situation or scenario, the process's structural information will still exist in the process table. As a Process is dead, it will not react to any signals. The kernel is responsible for clearing the resources of the Zombie state processes.

Q26) Briefly explain the differences between Bash and DOS? 

Ans:

BASH: The Bash command is referred to as a case-sensitive command. Bash command does not follow any convention. Under the dash command, the characters are the directory separator and acts as an escape character. 

DOS: DOS command is not Case sensitive command, and it follows a naming convention. Under those characters are referred to as the command argument delimiter.

Q27) Give a brief idea about symbolic links?

Ans: The symbolic links In Linux are referred to as the shortcuts used in windows. The symbolic link will be pointing to the codes, files, programs, or directories and will also allow direct instant access to the entire pathnames.

Q28) What do you mean by virtual desktop? 

Ans: A virtual Desktop usually refers to the alternative service used to minimize and maximize the multiple windows on the currently running desktop. The primary purpose of using the virtual desktop is for clearing and running one or more programs at one time. The virtual desktop will allow the users to perform the shifting between the desktop rather than minimizing; they are restoring the programs. 

Q29) List out the different process states in Linux? 

Ans: Below is a list of the different process states in Linux. 

1. New or ready process 

2. Running process 

3. Blocked or wait for the process 

4. terminated or completed the process 

5. Zombie process 

Q30) Briefly explain the different file permission groups available in Linux? 

Ans: There are three types of file permission groups available based on each file or directory. They are: 

1. Owner: The owner will generally have permission to access the file or directory; however, it will not impact any action of the Other groups. 

2. Group: The Group file permission will be assigned to the groups that are assigned to the directory for a file. 

3. All users: All user's file permission is applied to the users that are using this system.

Conclusion:

I hope you have got an idea about the most frequently asked questions in the interview to crack the Linux administration positions. These questions will definitely help you in gaining knowledge about the different concepts in Linux. I would also recommend you to get trained and certified for a better and in-depth understanding of Linux and its usage.