Getting Familiar with Shell Scripting

Introduction to Shell

The shell carries out the keyboard commands to the operating system in order to perform them. “bash” is the GNU project from which a shell program is provided by most of the Linux distributions. Terminal emulator is needed to interact with the shell when using a GUI. Here ‘terminal’ is used for that. There are many other terminal emulators for Linux, but what they all do is giving us the access to the shell. The shell prompt appears when the terminal emulator is launched.
Now let’s discuss about some simple shell commands. The date command displays the current time and date while the cal command displays a calendar of the current month.
The current free space on the disk drives can be displayed by the command df while the command free can be used to display the free memory space. A terminal session can be ended using the exit command.

Knowing core commands is important,because you will be able to adapt to new Linux releases easily. A shell is a program that runs commands like which are entered by the users and also works as a programming environment. Shell Script is a text file that includes a sequence of shell commands. If we accidentally make a mistake when typing a shell command, we can easily correct it as we can see what we have typed. Although their are numerous shells, all of them derives features from the standard shell; Bourne Shell (/bin/sh) developed at Bell Labs for the use of early versions of Unix. The bash shell is the default shell on most Linux distributions which is an enhanced version of the Bourne shell.