users have accounts on other machines under different login names.
This can happen when moving from one job to another, for example. At
the first job you might be named ellen and at
the next job you might have the login name
ewinstin. If your mail is being forwarded to you
from your old job, you can use this -a switch to
have vacation recognize you under your old login
name in addition to your current login name:
|"/usr/ucb/vacation -a ellen ewinstin"
You can add as many other names as you want by adding a
-a command-line switch for each. A system
administrator, for example, might have a half dozen names under which
mail is received:
|"/usr/ucb/vacation -a root -a postmaster -a bin -a sys kate"
Note that vacation does a word match when it
looks for each name. That is, only letters and numbers count in a
word, so root will not match
rootbugs, but will match
root+bugs or root@host.