The `who' command
=================
The first program is the `who' command. By itself, it generates a
list of the users who are currently logged in. Although I'm writing
this on a single-user system, we'll pretend that several people are
logged in:
$ who
arnold console Jan 22 19:57
miriam ttyp0 Jan 23 14:19(:0.0)
bill ttyp1 Jan 21 09:32(:0.0)
arnold ttyp2 Jan 23 20:48(:0.0)
Here, the `$' is the usual shell prompt, at which I typed `who'.
There are three people logged in, and I am logged in twice. On
traditional Unix systems, user names are never more than eight
characters long. This little bit of trivia will be useful later. The
output of `who' is nice, but the data is not all that exciting.