Possible Duplicate:
Why there are two users showing in uptime command results?
My MBP reports other users, but I'm the only one using this laptop:
$:> uptime
19:30 up 13 days, 16 mins, 3 users, load averages: 0.38 1.23 1.28
Who are the other 2 users?
They are just system accounts used for background services. You can view a list of all logged in users with the users command or the who command. Don't be surprised if it lists users more than once, that just means that user account has multiple login sessions running.
You can also use the ps command to view a list of processes running on your system, including which user account each is running under. This might help you get a better picture of what each account is used for.
Well, one would be your user, another would be 'root' - the user your system uses to run its services. One more might be another service runner. The easiest way to find out would be to run
ps u -A
and look at the first column - it'll tell you who's running what.
The BSD uptime command takes its user count from the utmp database. You can use users, who, w or finger to see all login sessions recorded by utmp.
Most likely, those three entries correspond to three Terminal windows you have opened; SSH and X11 sessions are registered in the same way. (I don't know if utmp applies to graphical logins on Mac OS X, but you can just see for yourself.)
