W (Unix)

The command w on many Unix-like operating systems provides a quick summary of every user logged into a computer, what each user is currently doing, and what load all the activity is imposing on the computer itself. The command is a one-command combination of several other Unix programs: who, uptime, and ps -a.

Example
Sample output (which may vary between systems): $ w 11:12am up 608 day(s), 19:56, 6 users,  load average: 0.36, 0.36, 0.37 User    tty       login@  idle  what smithj  pts/5      8:52am       w jonesm   pts/23    20Apr06    28 -bash harry   pts/18     9:01am     9 pine peterb  pts/19    21Apr06       emacs -nw html/index.html janetmcq pts/8    10:12am 3days -csh singh   pts/12    16Apr06  5:29 /usr/bin/perl -w perl/test/program.pl