You probably know that shells can be customized to work the way you want them
to with
shell and environment variables (
6.8
,
6.1
)
,
command aliases, shell functions (
10.1
)
,
and so on.
You can set variables and create aliases by hand at any time,
but the shell will "forget" your settings
when you log out.
To use the same settings every time you log in, put the commands in special
shell setup files (
2.2
)
in your home directory.
These files aren't just for setting things like shell variables.
Shells can run any UNIX command when you log in and log out.
All of this can save time and make your login session do more for you.