Some features to make life easier

This section contains some ways of working with the shell. You can do any of the following:

• Use environment variables or aliases to make your Korn or Bourne shell prompt tell you what your current directory is, or to display other useful information.

• 
  Use the Bourne or Korn shell trap command to specify actions to take when the shell receives a signal; for example, to execute a logout script.

• Use the Korn shell or C shell to recall and edit previously issued commands.

• Define complex aliases or functions to shorten long command lines or redefine commands.