BASH

 Probably the most popular command line shell with Linux distributions. The name came from a pun on Stephen Bourne, the author's name as Bourne Again SHell.

Bash is a shell, or command language interpreter.  Bash is an sh-compatible* shell that incorporates useful features from the Korn shell (ksh) and C shell (csh).  It offers functional improvements over sh for both programming and interactive use. In addition, most sh scripts can be run by Bash without modification. 

Scripts

A script is a text file with shell commands. The script needs to have the execute flag set before executing.

It can be set by chmod +x  filename the filename is  the name of the script file.

Below is a sample script for the iconic "Hello World" example that can be created with a simple text editor. The script file's executable flag must be set before running it.

#/bin/bash

# Hello World bash script

echo Hello World

When the above file (I named it helloworld)  is ran you should see something like the following.

~$ ./helloworld 

Hello World                           

Bash scripts can be a very powerful way to run all sorts of tasks.

Notice the pound sign # (Hashtag to the youngsters) means the line is a comment.

Links

Documentation

Example Scripts

Notes

* sh - shell, the standard command language interpreter that BASH is a improvement on. In most cases SH has been pretty much been replaced by BASH as the default shell. Read More on sh at: The Open Group Base Publications