Which Shell?

The shell commands form a complete programming language so script files can form another, powerful layer of programming. By default, the shell commands must be those of the shell you are currently in. So, if you use the C or T shells, your script files should contain C shell commands. If you intend to put a lot of effort into shell programming it would be wise to switch to the Bourne shell (or in Linux the bash shell) for a variety of reasons:-

• It is universally available.

• Although the syntax is sometimes a bit odd, its is a better programming language with far better control over pipes and I/O redirection.

For the most part this section on shell programming will use the Bourne (or bash) shells with explicit references to C shell where relevant.