Linux is one of the most popular operating systems that is known for its exceptional performance. According to a study, the average salary for a Linux developer ranges from $107,805 to $179,000. Thus, the job role of a professional Linux developer is lucrative and offers good career growth.
If you are preparing for a Linux interview and looking to get some help, you have landed just at the right place.
Based on the opinions of various Linux experts, we have curated a list of the most frequently asked Linux interview questions and mentioned their appropriate answers in this article. These interview questions can help you give your best during the interview.
Top 50 Linux Interview Questions and Answers
To begin, we'll answer some simple Linux interview questions and then progress to advanced-level questions so that you can prepare for your upcoming Linux interview effectively. Also, these Linux interview questions can come in handy if you need to prepare for an interview at the last minute. However, we recommend that you certify your expertise with a Linux certification to improve your odds of landing the position.
Nonetheless, let's begin discussing the most common interview questions and their answers below:
Basic Linux Interview Questions
1. What can you tell us about Linux?
Answer: Linux is an open-source and free operating system that is based on Unix. Linus Torvalds designed this operating system and built it on top of the Linux kernel. Since Linux is free, it is ideal for users who do not want to pay for premium operating systems like macOS and Windows.
2. What is the latest version of Linux?
Answer: The ongoing series of Linux is Linux5.x, and the latest version of the Linux kernel is 5.14.7 released on 22 September 2021.
3. Can you explain what is Bash?
Answer: BASH stands for Bourne Again Shell and it is the GNU operating system's UNIX shell. Also, BASH is a command language interpreter that assists you in entering data and retrieving information. In other words, we may conclude that BASH is a program that interprets the data entered by the user, executes certain instructions, and outputs the results.
4. Can you differentiate between Unix and Linux?
Answer: The following are some of the key differences between Unix and Linux:
- The most notable distinction between UNIX and Linux is that the latter is a free and open-source OS. It means that Linux users can access the source code of Linux and modify it if they want to. However, the UNIX operating system is not open-source and thus users can not modify it as per their requirements.
- When it comes to the versatility and reliability of both operating systems, Linux is more stable than UNIX and works well with various types of hardware.
- Linux has various graphical user interfaces, such as Gnome and KDE. On the other hand, Unix has only a single desktop environment.
- As compared to Unix, Linux updates are quicker.
5. Explain CLI in Linux.
Answer: The acronym CLI stands for Command-Line Interface . CLI is the user interface in Linux that allows a user to input commands and execute them. CLI is simple to use, but we need to be very careful while entering the commands in it.
6. Explain the use of the Linux Kernel.
Answer: The kernel in Linux is the most integral element of the Linux OS. In general, the kernel is the heart of an operating system, and when it comes to the Linux kernel, it is the core element of the Linux operating system. The kernel is in charge of dealing with hardware and user commands. Users may also use the terminal (CLI) to communicate directly with the kernel and communicate with the machine. The Linux kernel is also open-source, which means that anybody can download and modify it without authorization. Linux is distributed under the GNU General Public License, which allows it to be updated and edited according to the needs and specifications of users.
7. Explain Kdump in Linux.
Answer: Kdump is a Linux tool for capturing crash dumps when a machine encounters an error and fails. When a kernel panic happens, crash dumps may also be generated. A Linux administrator can choose whether to save the crash dump to a local or remote file server. The main purpose of the Kdump is to figure out what caused the crash and then repair it.
8. Explain Linux Loaded.
Answer: The Linux Kernel, or LILO, is the operating system's boot loader. The boot loader makes it possible for the operating system to load into memory and begin running. LILO functions in a similar way to other common operating system boot loaders, such as macOS and Windows. They are, though, all special in their own way.
LILO ensures that BIOS is started in order to monitor the whole device and guarantee that it runs properly. After the BIOS has completed its tests, it passes power to the Master Boot Record. After that, the LILO catches the whole power and starts the Linux OS. The whole procedure is fast, ensuring that the operating system boots up as quickly as possible.
9. What is Swap Space in Linux?
Answer: Swap space or area is the extra memory allotted by the Linux OS to run concurrently executing processes when they are required. It ensures optimum efficiency and utilization of the available memory. Once the processes are executed successfully, the RAM is completely open to other processes. Swap space is often used where RAM is insufficient to execute programs.
10. Can you explain Virtual Desktop?
Answer: A virtual desktop allows you to monitor several windows in a different environment. Virtual desktops can help users increase their productivity. A virtual desktop can also run on remote servers, which has additional advantages such as cost savings, energy efficiency, data confidentiality, reduced compatibility, and centralized management.
11. What is Root Account in Linux?
Answer: The account that has the privileges to perform system management is the root account in Linux. You can make any modifications to the system using the root account and you have complete control of it. In addition, the root account is the Linux operating system's default operating account. It is responsible for creating user profiles, assigning permissions, and managing them.
12. Explain GUI in Linux.
Answer: GUI is an acronym for the graphical user interface. GUI in Linux provides users with an immersive and user-friendly interface that makes it easier to use various functionalities of the Linux operating system.
13. Mention Linux File Permissions.
Answer: There are three levels of file permissions in Linux that users can get. The following are the definitions of each file permissions level: Read: Users with the read permission can open and read the contents of a file. For files with read permission, the user may also list the contents of the archive. Write: The write permission allows a user to change the contents of a file. The user has the choice or authorization of adding or removing file content. Also, users can rename the file at the directory level. Execute: Any file in the directory can be executed with the execute permission. To run a file, you'll also need the execute authorization.
14. Why is Linux more secure than other OS?
Answer: Thanks to its open-source licensing, Linux is comparatively secure than other OS out there. Linux is more secure for a variety of reasons such as having a large community of developers that test Linux source code for vulnerabilities and fix them immediately. Following are some more reasons for Linux to be more secure:
- Improved user control and low-level limitations. Viruses are unable to attack local files or directories in this manner.
- Permissions may also be granted to programs before they are installed, providing better protection.
- Linux has a robust auditing scheme.
15. Explain Daemons in Linux.
Answer: The operating system will use Daemons to execute a background operation that isn't native to the operating system. System managers use Daemons to run background services. This ensures that consumers are unable to communicate with the programs, making them more stable. In short, when it comes to managing periodic requests, Daemon is a safe option.
16. What are ENV variables in Linux?
Answer: They are memory locations for storing dynamic values that have an effect on the way programs run on a machine. They can be used in any operating system and come in a variety of types. They can be generated, modified, saved, and removed, and they also provide data on device activity.
17. Explain troubleshooting in Linux.
Answer: Linux is a cutting-edge operating system with comprehensive networking capabilities. As a result, Linux can be used to transmit and retrieve data both internally and externally. The network setup and proper troubleshooting are the duty of the root user or system admin. Also, it is possible to use the Linux commands to initiate troubleshooting.
18. What are Soft Links or symlinks in Linux?
Answer: It is a referral link that can be used to redirect to another directory or file. It’s just a link and does not hold any kind of content or data. These links point to a different location in the file system. The relation to the target file is lost when the link is deleted, but not the file itself.
19. Explain hard Links.
Answer: On Linux, a hard link is another term for an existing file. For any file, we can build an unlimited number of hard links. They have the capacity to create links to other hard links as well. It's just like a copy of the file.
20. What is LVM in Linux?
Answer: Large Volume Management (LVM) is a data management system. Users can create, resize, and delete LVM partitions. It improves abstraction, power, and stability. Moreover, LVM groups together current storage systems and assign logical units to them.
21. Explain network bonding.
Answer: Network bonding is the method of merging more than two network interfaces to form a single network interface. By - network throughput and bandwidth, it improves efficiency and redundancy. If one interface fails or is unplugged, the other can continue to work. The bonding process determines how the bonded interface behaves.
22. What is the Maximum Filename Length in Linux?
Answer: It is 255 characters (for a typical file in Linux). This farthest point does include the pathname, so the total pathname and filename length could easily exceed 255 characters. This is a common Linux interview query, and the interviewer will always follow up by asking if the length listed contains the pathname. So, plan a full response and clarify it before the interviewer presses you for more details.
Intermediate Linux Interview Questions
23. Differentiate Cron and Anacron.
Answer: Cron and Anacron are two daemons that are useful in scheduling activities in Cron jobs. Both of these are daemons are used to schedule a command or task execution based on the details provided by the user. Here are the key differences between the two:
- One of the primary differences between Cron and Anacron occupations is that Cron operates on systems that run constantly, i.e., it is optimized for systems that run throughout the week. On the other hand, Anacron is used for applications that are not constantly operating.
- Another distinction is that Cron jobs can run every minute, while Anacron jobs can only run once a day.
- Cron jobs can be scheduled by any regular user, but Anacron jobs can only be scheduled by the superuser.
24. Explain ext3 in Linux.
Answer: It is possible to react in the following manner. Ext3 is better than the ext2 file system as it allows journaling. During an unclean shutdown, the ext2 file system runs a lengthy error scan on the machine, but this is not the case for the ext3 file system.
In the event of a hardware breakdown, an ext3 consistency search for the possible reasons for the breakdown. The total amount of files has no stance on the time it takes to restore the file system. The period is determined by the size of the journal, which takes just a second and is based on the hardware's speed.
25. What are INODEs in Linux?
Answer: INODE is an arrangement that works like a sole identifier for all files and objects in a directory. In the shell, type the order "ls -i." The numbers next to files and directories are INODE numbers, which are allocated to each file and provide information about it. This number is used by the machine to label the file.
An INODE number contains information such as the file's size when it was last edited, and so on. INODE-based questions are the most popular Linux interview questions you'll encounter. So, read carefully and gain sufficient information about INODEs.
26. Can we make a router using Linux?
Answer: This sort of question is often asked in Linux interviews. With the support of IP Masquerade, a Linux system can be modified or converted into any type of router. The servers used in commercial firewalls may be familiar to you. IP Masquerade is a one-to-many Network Address Translation server that performs the same purpose. If the internal computers do not have an IP address, IP Masquerade will link to the internet from the other internal computers that are attached to the Linux box.
27. What is shell or bash scripting?
Answer: Bourne Again Shell is the full form of bash. The UNIX shell executes the programs in a command-line interpreter, which allows programs to have several dialects. There are several commands that are a combination of various commands.
File editing, program compilation and execution, and text processing are all standard operations in every scripting language. These scripts are mostly used for server management. Invocation tools are included in Bash, and the look can be personalized by scripting. They also assist in the installation of advanced programs.
The .bashrc extension is used to save the files. Shells are usually collaborative, which means they accept user commands as input and execute them. However, there are times when we need to run a series of commands on a regular basis, and we must type all commands into the terminal each time. We can write these commands in a file and execute them in the shell to prevent this tedious work because the shell can take commands from files as input.
Shell Scripts or Shell Programs are the names given to these files. The batch file in MS-DOS is identical to shell files. Each shell script has a .sh file extension, such as myscript.sh.
28. How will you print the present working directory?
Answer: The command pwd is very useful. Print Working Directory is what pwd stands for. It allows you to display the path of the directory where the program is run. From the root, the directory path is shown. You will see the whole route starting from the root if you enter $pwd in the command line gui. It also supports the -L and -P flags, which cause the path to return in the symbolic and absolute paths, respectively.
29. Explain MBR in Linux.
Answer: MBR stands for Master Boot Record and is also known as the master boot block, sector 0, or the master partition boot zone. The MBR is the very first sector of the hard drive that instructs the computer on how to install the operating system, partition the hard drive, and load the operating system.
30. Define Interrupts in Linux.
Answer: Interrupts occur when the processor is momentarily switched to another program or operation. When the program is over, the processor will be returned to it to finish the job. The kernel's interrupt handler is a mechanism that runs in response to a given interrupt. Interrupt Service Routine is another name for it. Interrupt handlers are the functions that fit a specific prototype and allow the kernel to correctly transfer handler information.
31. What is a Device Tree?
Answer: A device tree is a data structure for extracting redundant codes from various boards. They are loaded into memory as a binary file with the aid of a bootloader. The kernel is resonsible for settling the system tree structure on the binary.
32. Can you reduce the kernel size?
Answer: There are certain code snippets that aren't used or executed; we can detect them and uninstall them to speed up the project's processing. The kernel includes an editor called "kernel's configuration editor" that allows one to delete and disable non-essential code chunks.
33. Explain fundamental Linux Components.
Answer: Kernel, shells and GUI, system libraries, system tools, and applications are the core components of Linux. Here's a brief description of each component:
Kernel: The kernel is responsible for all operating system tasks, including processes and virtual memory.
System Libraries: The system libraries are responsible for certain common activities that interact with the kernel.
Shells And GUI: Shells and graphical user interfaces (GUIs) are the kernel's interfaces responsible for communicating with users and executing kernel functions.
Applications: Applications allow users to carry out various functions.
34. Explain some benefits or advantages of using Linux.
Answer: The following are some remarkable benefits of using Linux:
- Linux is scalable and compliant with a wide range of technologies and applications due to its open-source nature.
- It is highly secure against cyber threats.
- Linux does not need a license fee.
35. Explain a Zombie process.
Answer: A zombie process is the byproduct of a previously completed process. In general, a process that has been completed but still has its remains in the memory and has not been erased directly after the execution is known as a zombie process. In this situation, the parent process' intervention is necessary to determine the exit status of the child process.
36. What is the usage of the top command in Linux?
Answer: The top command displays the operations of Linux processes. Furthermore, it illustrates the kernel's real-time task management status. It also displays all of the operations performed by the processor and memory.
37. Explain the concept of journaling in Linux Servers.
Answer: In Linux, the “journaling” file system is used, and the journal file's primary aim is to create a file that recovers information about data that has been destroyed and deleted due to malfunctions or incorrect shutdown of a laptop. The power supply or crashing applications that cannot be fixed by rebooting are the most frequent causes of this disruption.
38. Explain the term patching used in Linux.
Answer: Patching is a Linux computer utility that includes modified text files as well as a special file known as the patch file. It is a little text document that fits in between two different copies of a source tree that's full of updates. In addition, the diff software is used to create a patch that fits the diff listing form.
39. What is Redirection in Linux?
Answer: Any instruction takes input and shows the output. The standard device for taking input is the keyboard, and for the output, the standard device is the screen. Redirection is the method of directing data from one output to another.
40. Explain file descriptor which is a common term in Linux.
Answer: The “file descriptor” is a conceptual indicator in Linux. It is usually a number that enables us to view input or output channels as well as files. If data is needed, the in-network socket and pipe command specify how they should be accessed. In certain cases, the file descriptor allows the kernel to facilitate access to the global file table and provides the precise location for that program.
41. Explain the usage of pipe in Linux.
Answer: In Linux, "pipe" is a parallel command that allows you to run two commands at the same time. For example, the output of one program may be used as the input for another. To put it another way, the output of one process is simply the input of another process, as if it were a pipe; therefore, it is known as the "pipe" command.
42. What is the mkdir command in Linux?
Answer: We use the make directory or mkdir command in Linux to create directories. You can use several options along with it to create multiple directories, set permissions, etc.
43. What is the use of the man command?
Answer: The "man" command is a user-friendly way to view and format man pages. The man command is in charge of metadata for library routines, kernel configuration files, and system calls, among other things.
44. Why do you use grep commands in Linux?
Answer: Grep is an acronym for ‘global regular expression print.' Using this command, we can compare text in a file against a standard expression. After this command performs pattern-based scanning, it shows only the matching lines as output.
Advanced Linux Interview Questions
45. Explain the init process.
Answer: Initialization, abbreviated as "init," is the first step in a Unix-like operating system that begins running at the outset of the boot stage and continues until the system shuts down. It is a daemon process that is the direct or partial ancestor of all other processes and accepts all orphaned processes.
46. Explain automounter in Linux.
Answer: Automounter is a Linux utility that manages both local and remote file system mounting. When the device requires it, the service automounts the appropriate picture. This ensures that even though the drive is required, the machine does not need to keep mounting it. When the file system is required, the autofs automounter service mounts it.
47. What are the uses of head and tail commands in Linux?
Answer: If a file has too much content, instead of using the cat or less command to print the entire file, we can use the head command to print the first ten lines of the file, or the tail command to print the last ten lines of the file.
48. How can you see the file permissions in Linux?
Answer: We know that the ls command lists all the directories or files in a defined location. If we use the ls command with the -l option, we will be able to see details regarding each file and directory such as owner, group, permissions for user, group members, date-time stamps, location, file type, etc.
49. How can you compress or extract files in Linux?
Answer: In Linux, we can use the tar command to compress and extract files. We can either use the gzip or bzip2 compression mechanisms. If we use the -c option along with the tar command, it will compress the specified directories, and if we use the -x option, it will extract them. Also, we can use zip and unzip commands to create zipped files in Linux.
50. How can you change file ownership?
Answer: In Linux, for each file, there are two types of owners - user and group members. We can change both types of ownership using the chown command . To change the group ownership, you need to be the owner of the file or the sudo user.
51. What are the different ways to print or view file contents in Linux?
Answer: You can use commands such as cat or less to print the file contents in the terminal itself. You can also use file editors such as vim, etc. to modify and print the files.
Wrapping it Up
The collection of the most commonly asked Linux interview questions and answers listed above comes in handy for a last-minute interview training guide. These questions are beneficial to both new and seasoned Linux developers.
Additionally, by going through the top Linux interview questions, you will be able to understand various Linux concepts better, and thus give your best in the interview.
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