UNIX Interview Questions and Answers

UNIX Interview Questions and Answers, UNIX Fundamentals, Types of UNIX, Features of UNIX, The Architecture of UNIX, and Basic UNIX Commands.

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The Full Form of UNIX is UNiplexed Information Computing System. A highly popular and multitasking Operating system.

UNIX Interview Questions and Answers

1. What is UNIX?

UNIX was earlier known to be UNICS, which stands for UNiplexed Information Computing System..

UNIX is a popular operating system, first got released in 1969. UNIX is a multi-tasking, powerful, multi-user, a virtual OS which could be implemented on a variety of platforms(Eg. Desktops, Laptops, Servers, and mobile devices, etc.).

2. What are the three important components of UNIX?

The UNIX system basically comprises three components:

i. Kernel:
The Kernel is responsible for allocating time and memory to programs. It also handles file storage and communication while responding to the system calls.

ii. Shell:
It acts as an interface between the kernel and the user. The user has to go under the authentication check before entering into the shell.

iii. Program:
It can be said that everything inside UNIX is either a file or a program. A process is a program under execution having unique PID(program Identifier), used to identify it.

3. What are the different types of UNIX?

There are many different versions of UNIX, although they share common similarities. The most popular varieties of UNIX are Sun Solaris, GNU/Linux, IBM – AIX, HP UNIX, BSD and MacOS X.

Linux in its turn is packaged in a form known as a Linux distribution. There are several Linux distributions, both free and commercial.

4. Define a single-user system?

A personal computer which possesses an operating system designed to operate by only one user at a given time is known as a single-user system. Single user system becomes more popular since low-cost hardware and availability of a wide range of software to perform different tasks.

5. List a few significant features of UNIX?

The following are a few features of UNIX;

Machine independent
Portability
Multi-user operations
Unix Shells
Hierarchical file system
Pipes and filters
Background processors
Utilities
Development tools

6. What is Shell?

The program which serves as an interface between the user and the system called a shell. It is the layer of programming that understands and executes the commands a user enters. In some systems, it’s also called a command interpreter.

6. Name the commonly used shells on different UNIX/Linux variants?

i. The Bourne Shell (bsh)
ii. The GNU Bourne-Again Shell (bash)
iii. The C Shell (csh)
iv. The Korn Shell (ksh)
v. The Z Shell (zsh)

7. What is the role of kernel?

It interacts with hardware and most of the tasks like memory management, task scheduling and file management.

8. What is a FIFO?

FIFO are otherwise called as ‘named pipes’. FIFO (first-in-first-out) is a special file which is said to be data transient. Once data is read from named pipe, it cannot be read again. Also, data can be read only in the order written. It is used in interprocess communication where a process writes to one end of the pipe (producer) and the other reads from the other end (consumer).

9. Describe a link in UNIX?

Link is used to assigning more than one name to a file. It is like a pointer to a file and one file can have multiple pointers. There are two types of link

Hard link- These hard-linked files are assigned to the same inode value as the original and thus reference the same physical location of the file. Also if the file is moved to a different directory the link will still work

ln [original filename] [link name]

Symbolic link- A soft link is similar to the file shortcut feature and it contains a separate inode than the original one. If the original file is moved then the link might not work, but it can reference across the different file systems.

ln -s [original filename] [link name]

10. What is meant by the term Super User?

The Super User is a user with access to all files and commands within the system. In general, this superuser login is to access root and it is secured with the root password.

11. What is filter?

A filter is a program that takes input from standard inputs and performs some operation on that input to produce a result as standard output.

12. What is necessary before running a shell script from the terminal?

You must make the shell script executable by using the UNIX “chmod” command.

13. Differentiate multiuser from multitask?

Multiuser means that more than one person can use the computer at the same time. Multitask means that even a single user can have the computer work on more than one task or program at the same time.