The Ultimate Guide to Acing Linux Programming Interview Questions

Landing a job as a Linux programmer is no easy feat. The competition is fierce and employers expect candidates to have an in-depth understanding of Linux systems and programming. Being well-prepared to tackle the challenging technical questions thrown your way during the interview process is critical to stand out from the crowd.

This comprehensive guide takes you through the 25 most common Linux programming interview questions, providing tips and examples to help formulate winning answers. Master these questions, and you’ll walk into interviews with the confidence to impress. Let’s get started!

What is Linux? Explain the Basic Features of the Linux OS

Linux is an open-source and community-developed operating system based on the Unix architecture. Unlike proprietary operating systems like Windows or macOS, the Linux source code is freely available and can be modified and redistributed.

Some key features and advantages of Linux include

Free and open source – Linux source code is accessible to anyone to view, modify and share. This drives innovation through collaboration.
Portability – Linux can run on various hardware architectures like x86, ARM, PowerPC. This makes it adaptable across devices.
Stability – Linux systems are known to be stable and reliable due to their modular architecture. System crashes are rare.
Security – Linux has a multi-user design with strict file permissions. Its code can be easily audited for vulnerabilities.
Customizable – Users can fine-tune Linux distributions to their precise needs by adding/removing components as required.

Name Some Popular Linux Distributions

There are hundreds of Linux distributions or “distros” built on top of the Linux kernel. Some popular ones include:

Ubuntu – Debian-based distro ideal for beginners. Backed commercially by Canonical.
Linux Mint – Ubuntu-based desktop distro focusing on easy usage and aesthetic appeal.
Debian – Pioneering distro favoring stability over bleeding-edge updates.
Fedora – Community distribution sponsored by Red Hat providing latest innovations.
openSUSE – Offers flexibility with RPM packaging system. Developed by openSUSE project.
CentOS – Free RHEL clone commonly used for web servers and enterprise apps.
Kali Linux – Penetration testing and ethical hacking distro packed with security tools.
Arch Linux – DIY distro for advanced users providing minimal base install.

What are the Major Differences Between Linux and Windows?

There are critical differences between the Linux and Windows operating systems:

Linux is open source while Windows is proprietary and closed source.
Linux has free community-based support whereas Windows support comes at a considerable cost.
Linux users predominantly use command line while Windows emphasizes GUI.
Linux can function well on older and resource-constrained hardware but Windows requires ample powered hardware.
In Linux, programs and libraries follow common standards allowing interoperability. Windows uses diverse proprietary technologies.
Linux is natively more secure with strong access controls whereas Windows has higher malware risk.
Linux allows greater customization and tweaking of the OS to user needs compared to Windows.
Linux distros generally consist only of the kernel and essential components. Windows comes with many pre-installed applications.

Define the Basic Components of Linux

The key components that make up a Linux OS are:

Kernel – The core of the system responsible for managing system resources, CPU scheduling, memory allocation, hardware interfaces and more.
Init system – Bootstraps user space, manages system processes, launches daemons and handles shutdown/reboot. Examples: systemd, SysVinit.
Shell – Interpreter through which users and applications interact with the kernel. Bash and sh are common Linux shells.
Filesystem – Enables storage and retrieval of data in a hierarchical tree of directories and files. Ext4 and XFS are typical Linux filesystems.
Package manager – Administers installation, removal, upgrading of software packages from organized repositories. e.g. apt, rpm, pacman.
Graphical server – Allows users to interact with visual desktop environment. X11 is the traditional Linux display server.
Desktop environment – Provides consistent look and UI conventions for applications. GNOME, KDE are popular Linux desktop environments.

Elaborate on All the File Permissions in Linux

Linux file permissions dictate the level of access permitted to file owners, groups and other users for a given file or directory. They are represented as a sequence of symbols:

First symbol: file type. – indicates regular file, d indicates directory.
Next 3 symbols: permissions for the file owner – rwx denotes read, write, execute access.
Next 3 symbols: permissions for the group owner.
Final 3 symbols: permissions for other users not in the file owner group.

The chmod command is used to change permissions. For example, chmod 755 assigns read, write, execute access to the owner, but only read and execute access to groups and others.

What is the Linux Kernel?

The Linux kernel is the central component of a Linux OS. It acts as the interface between hardware and processes, managing computational activities. Key functions include:

Memory management – Managing and allocating memory to processes
Process scheduling – Determining which processes get access to CPU and for how long
Filesystem management – Handling filesystems supported by Linux
Device drivers – Software enabling the kernel to interact with peripheral devices
Networking – Facilitating network and internet connectivity
User access control – Managing user permissions on system resources

The kernel remains in memory the entire time the system is running. It is updated periodically to add support for new hardware and tweak performance.

Explain LILO (Linux Loader)

LILO (Linux Loader) is a bootloader program used to load the Linux kernel into memory and start the operating system during bootup. Here are some key points about LILO:

It contains information on available kernel images and configured boot options.
Located in the master boot record (MBR) or the boot sector of a disk partition.
Displays a prompt allowing users to choose which kernel to boot into.
Can be configured by editing /etc/lilo.conf file to set kernel locations, boot options, graphics interface etc.
Runs the /sbin/lilo command to update bootloader configurations to the MBR.
Advantage over GRUB is compact size, but modifying kernel options requires re-running /sbin/lilo.

While still used, LILO has largely been superseded by more advanced bootloaders like GRUB in most Linux distros.

What is Swap Space in Linux?

Swap space in Linux is a reserved amount of disk space used as virtual memory to supplement insufficient physical RAM memory. Key characteristics:

Used when active processes exceed the available physical memory.
Inactive pages in memory get temporarily moved to the swap space.
Swap space is allocated when installing Linux but can also be added later.
Located in dedicated swap partitions or swap files.
Slower to access than physical memory but faster than retrieving data from disk.
Having extra swap space is recommended for stability though excessive use hurts performance.
Swappiness parameter configures how readily the kernel uses swap space.

What are Process States in Linux?

The Linux kernel handles processes by assigning them various states. The key process states are:

Running – Process currently executing instructions on a CPU.
Waiting – Process waiting for an event like user input, I/O completion before resuming execution.
Uninterruptible Sleep – Process waiting for disk I/O to finish before continuing.
Stopped – Process execution halted but kept in memory by a signal.
Zombie – Process has terminated but entry still in process table.
Killed – Process terminated forcibly due to exception like memory error.

The ‘top’ command shows processes with their corresponding states indicating how the CPU resources are being utilized.

What is a Linux Shell? Name Some Common Ones.

A Linux shell is a command-line interface that allows users to interact with the operating system. Some common Linux shells are:

Bash (Bourne Again SHell) – Default shell on most Linux distros with useful features like command history, auto-completion.
Zsh (Z Shell) – Advanced interactive shell inspired by Bash with themes support, alias expansion etc.
Csh (C SHell) – Provides C language syntax style with convenient features for scripting.
Tcsh – Enhanced C shell with added functionality like command completion and spell check.
Ksh (Korn SHell) – Backward compatible Bourne shell supplementing useful command editing features.
Fish (Friendly Interactive SHell) – Supports powerful auto-suggestions, syntax highlighting and man page integration.

Shells allow automation of tasks through scripting and access to core OS functionality making them integral to Linux.

Explain Different Modes Used in Vi Text Editor

The vi editor available in Linux has 3 modes:

Command mode – Used to execute commands like cursor navigation, copy/paste, search etc. No text insertion or deletion is possible in this mode.

2 What is CLI and GUI?

CLI stands for “Command Line Interface.” It is a type of command-line program that usually takes text as input to run operating system functions. It lets people type declarative commands to tell the computer what to do. Using it usually takes less memory than other interfaces. You don’t need Windows to use it, and you can use a monitor with a low resolution. Usually, it gives you more options for how to use it, and you can easily do things that are hard to do with GUI. Graphical User Interface, or GUI, is a type of human-computer interface that lets people use electronic devices by showing them what to do with pictures and icons. The use of these graphical elements or icons makes it easier for users to interact with the system. It is visually intuitive and allows higher productivity. It is usually a combination of graphical and textual interaction that uses menus, buttons, message boxes, etc.

What is the function of grep command?

The command “Grep” (Global regular expression print) is used to look for a string of characters in a file all over the world. The text search pattern is generally known as a regular expression. It simply makes use of pattern-based searching. Syntax: grep [options] pattern [files] Example: $ grep -c “linux” interview. txt The above command will usually print the total count of the word “Linux” in the file “interview. txt”.

Linux Interview Questions and Answers 2022 | Linux Interview Questions for Beginners | Simplilearn

FAQ

What is basic knowledge of Linux?

Linux® is an open source operating system (OS). An operating system is the software that directly manages a system’s hardware and resources, like CPU, memory, and storage. The OS sits between applications and hardware and makes the connections between all of your software and the physical resources that do the work.

What is the difference between Linux and Unix?

Linux is an open-source operating system. This OS is supported on several computer platforms and includes multiple software features that handle computer resources, and allow you to do tasks. Unix is a powerful and multitasking operating system that behaves like a bridge between the user and the computer.

What questions do engineers ask during a Linux interview?

Engineers, developers, and systems administrators are most likely to be asked questions about Linux operating systems. If during an interview you do not know the answer, explain how you would go about finding the answer and your thought process for moving forward.

How to prepare for a Linux interview?

If you are looking for more in-depth preparation before your interview, Linux Technical Interview Questions is a highly rated course on udemy. There is also a pocketbook available for brushing up on all the basic Linux commands, relevant for Linux Interview. Check out some of the best Linux system administration tutorials.

How many questions should you ask in a Linux interview?

These 15 questions will revolve around your experience and help you in preparing for the advanced-level Linux interview: 31. What is the /proc file system? /proc (Proc File System) is the virtual file system that shows information about the system and the Kernel data structures.

Are Linux interview questions a good idea?

Using tricky Linux interview questions as part of your hiring process is a great way to help you identify the leading candidates for your position. You can use these questions to assess technical knowledge, problem-solving skills, and behavioral traits while removing as much bias as possible from the hiring process.