In-line editing provides the ability to edit the current or previous commands before executing them. There are three in-line editing modes available: emacs, gmacs, and vi. The in-line editing mode is specified by setting the EDITOR or VISUAL variables, but if neither variable is set, the default is /bin/ed. The in-line editing mode can also be specified with the set –o command like this:
$ set —o option
where option can be emacs, gmacs, or vi. This is usually specified in your $HOME/.profile file.
The size of the editing window is specified by the COLUMNS variable. The default is 80, unless COLUMNS is set. Some systems use the window size as the default. The size of your command prompt also affects the width of the editing window. ...