use PS1 to give naive users a menu

[David Sherman]

I've found that using the shell's prompt string (PS1) can be
a really easy way of giving computer-naive users a menu of
available commands, if the command set they need is very limited.
The bare "$ " of the shell can be intimidating, after all. Our
Director of Education has this in his .profile, for example:

PS1='Type "mail", "notes", "learntax" or "bye": '
-- 
{utzoo pesnta nrcaero utcs}!lsuc!dave
{allegra decvax ihnp4 linus}!utcsrgv!lsuc!dave