Its often useful to know just how many users are logged onto your system. As
I mentioned earlier, each process requires resources to run. The more users who
are logged on to your system, the more processes there are using your
resources. In many cases, just seeing how many users are logged in rings bells
and turns on lights in your head to say that something is not right.
The easy way to figure out how many users are logged in is with the who
command. Without any options, who simply gives you a list of which users are
logged in, the terminal into which each user is logged, and
the time each user logged in. If you use the
root root root jimmo
For every user logged in, there is at least one process. If the user first
gets to a shell and starts its
application that way, it probably has two processes: the
login shell and that application. Therefore, the minimum is
the number of users times two (assuming the application isn't the login shell).
Granted, the shell is sleeping, waiting for the application to finish, though it
is still taking up system resources. Plus, dozens of system process are running,
also taking up system resources.
Although I rarely use who with any option except