What are the shells available in LINUX OS?

Generally shell is a software program that acts as a mediator between the kernel and the user. It reads the commands and interrupts by sending requests to execute a program. So, the shell is known as a command interpreter.

It contains almost 100 system calls. It tells the kernel to carry out various tasks for the program. These tasks are as follows −

• Opening a file.

• Writing a file.

• Obtaining information about a file.

• Executing programs.

• Terminating a process.

• Changing the priority of processes.

• Getting the time and date.

A shell is a layer of user programs that executes our commands. It is like an interface to the operating system to do our work with suitable commands.

For example, if we want to create a directory, we can pass the command mkdir ‘filename’. The shell executes it on the operating system and creates a directory.

Types of shells

The different types of shells available in LINUX are −

• Bash shell

• Tcsh shell

• Ksh shell

• Zsh shell

• Fish shell

Features of shells

The features of shells are as follows −

• Command-line editing is easy in bash shell.

• We can easily maintain job control.

• Unlimited size command history.

• Shell functions and aliases are available in a huge collection.

• Unlimited size indexed arrays which help in faster searching and accessing.

• It allows integer arithmetic bases from two to sixty-four which is tremendous.

Advantages of shell scripting −

• Frequently performed operations are automated

• The sequence of commands are run as a single command

• It is easy to use

• Portable means we can run this in any Unix-like operating system.

Disadvantages −

• Compared to any programming language the execution speed is slow.

• For every shell command executed a new process is launched.