11.8.1 Who Is Doing What: w

With the command w, find out who is logged onto the system and what each user is doing. For example:

tux@mercury:~> w
 14:58:43 up 1 day,  1:21,  2 users,  load average: 0.00, 0.00, 0.00
USER     TTY        LOGIN@   IDLE   JCPU   PCPU WHAT
tux      :0        12:25   ?xdm?   1:23   0.12s /bin/sh /usr/bin/startkde
root     pts/4     14:13    0.00s  0.06s  0.00s w

If any users of other systems have logged in remotely, the parameter -f shows the computers from which they have established the connection.