Possible Duplicate:
Logging in or on?
Which is standard: “log on/off” or “log in/out”?
Using linux, when we type:
$ man who
WHO(1) User Commands WHO(1)
NAME
who - show who is logged on
SYNOPSIS
who [OPTION]... [ FILE | ARG1 ARG2 ]
DESCRIPTION
Print information about users who are currently logged in.
...
What's the difference between the logged on and logged in here?