Unix Interview Questions and Answers

Last updated on Mar 08, 2022
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Unix Interview Questions

Unix is a stable and secure operating system that is capable of handling commands from multiple users at the same time. The innermost level of the Unix environment, Kernel coordinates the computer internals and allocates all the resources. Users can communicate with the kernel through a program known as a shell, which translates commands written by the user into a language that the kernel can interpret. Want to clear interviews in one shot? Read our Unix interview questions.

Advantages of Unix

  • Each big task can be split into simple commands and utilities
  • Can be used on a variety of machines
  • Can run many programs with less physical memory consumption
  • Multiple users can perform various tasks at the same time without interfering with each other’s work. Each user’s work is protected.
  • Cleanly defined permissions and access for each user for each file.

Most Frequently Asked Unix Interview Questions

Here in this article, we will be listing frequently asked Unix Interview Questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.

Q1. What are the file permissions and access modes in Unix?

There are three types of permissions – owner, group and other (public), all of which can be listed using the command ls -l. Each user can have one or more of the following access – read (r), write (w), execute (x). Example, -rwxr-xr-- represent the file permissions for owner, members and everyone else as –

  • Characters 2-4 (rwx) – means the owner has read, write and execute permission,
  • Characters 5-7 (r-x) – indicates that the group has read and executed permission,
  • Characters 8-10 (r--) – indicates that everyone else has only read permissions.
Q2. 17. What are the common directory management commands in Unix?
  • cd – change directory
  • pwd – current directory
  • mkdir – create a new directory
  • rmdir – remove an empty directory
Q3. What is Unix and why is it important?

Unix is an operating system that supports multitasking and multi-user capabilities. Unix provides a simple and user-friendly interface for users. It is the first OS to be written in high-level (C) programming language.

Unix is important:-
  • Firstly, because of its design attributes from the initial release itself. That is, each complex task is divided into small, modular utilities that are easy to do.
  • Secondly, during the initial internet boom, most web servers were UNIX machines from IBM, Sun, etc., hence making it a standard system for web servers.
Q4. What is a filter in Unix? Give an example.

The filter is a program that gets its data from the input stream and prints the results to the output stream. Examples – grep, sort, tail, head, cut, etc.…

Q5. What is the role of the kernel in Unix?

The kernel is the central control of Unix. Kernel is the first part to be loaded when the OS loads and remains throughout the session. It executes processes, manages memory and handles interrupts and system calls. It provides drivers for controlling the hardware.

Q6. How to install Unix on Windows 10?

Unix can be installed on Windows 10 using VirtualBox, an open source virtualization tool.

  • Download VirtualBox (https://www.virtualbox.org/wiki/Downloads) and create a virtual machine. Select memory and virtual hard disk requirements.
  • Download the ISO image file from a reliable source.
  • Install the distribution in the VirtualBox in seamless mode.

Alternatively, you can install Unix in dual boot.

Q7. How is Unix different from Linux?

Linux can be said as a clone of Unix with the following differences –

1. UNIX does not have a free version. Linux is open source and freely distributed.
2. Requires more wait time for an issue to be fixed properly Community-based; hence solutions are faster.
3. It is mainly used for web servers, PCs and workstations. Can be installed on any device, tablet, mobile, PC, etc.
4. Source code is not available Open source, code is available for everyone.
5. Different versions are AIS, BSD etc… Different versions are Redhat, Solaris, Ubuntu etc…
Q8. What are the essential features of the Unix operating system?
  • It is a multi-user, multitasking system
  • Uses kernel and shell to execute commands and complete tasks
  • Hierarchical file system
  • Easily portable to other machines as the code can be easily changed and compiled.
  • Has pipes and filters to divide complex tasks into smaller utilities and then combine them.
  • Application code is independent of the hardware vendor.

Continue reading our Unix interview questions list to know more about each of these features.

Q9. What are different types of files in UNIX?
The different types of UNIX files are –
  • ordinary files – text, data or program instructions.
  • directories – stores regular and special files.
  • special files – device files, used for input and output operations.
  • pipes – temporary file that holds intermittent data until the second last command.
  • sockets – allows advanced communication between several processes.
  • symbolic links (soft links) – contains the path to another file (reference file)
Q10. How to compare two text files in UNIX?

In our list of Unix interview questions, we have covered all the essential aspects of Unix. Read on to know more.

Development History

Unix was developed at AT&T Bell Labs by Ken Thompson and Dennis Ritchie in 1979. The first portable version of Unix was V7. Check out our Unix interview questions list to understand how Unix processes command written by the user.

Latest version

The latest version of Unix is ‎4.20.8 released on 12 February 2019.

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