What shell scripts are used for
Writing shell programs
Using shell variables
Using shell constructs
Writing shell functions
The part of any system that interprets keyboard or mouse commands is called the shell. Under MS-DOS, for example, the shell is called COMMAND.COM; under Windows 95/98, the graphical shell is called EXPLORER.EXE. Under most UNIX systems, users have their choice of shells in both the graphical and text-mode environments.
The most popular Linux shell is bash. This stands for Bourne Again Shell, and is named after one of the original UNIX shell designers. bash has a lighter relative, ash, which lacks some features such as command-line histories, but requires substantially less memory and is therefore ...