With no arguments, prints out all currently-defined aliases.
With one argument, prints out that alias.
With more than one argument, creates a new alias or changes an old one.
‘unalias [alias...]’
‘una [alias...]’
Takes a list of names defined by alias commands and discards the
remembered groups of users. The alias names no longer have any
significance.
‘alternates name...’
‘alt name...’
The alternates command is useful if you have accounts on several
machines. It can be used to inform mail that the listed addresses are
really you. When you reply to messages, mail will not send a copy of
the message to any of the addresses listed on the alternates list.
If the alternates command is given with no argument, the current set of
alternate names is displayed.