Learning Who Else is Logged in with w
Another way to find out about other people logged into the Unix system is to use w, which tells you who is logged in, what they're doing, and a few other details (Code Listing 7.11).
To find out who is logged in with w:
Code Listing 7.11. The w command provides tons of information about the system and its users
[ejr@hobbes ejr]$ w 1:49pm up 6 days, 4:21, 6 users, load average: 0.08, 0.02, 0.01 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT ejr tty1 Wed 7am 3:36m 7.07s 6.01s -bash root tty2 Wed 3pm 28:46m 1.22s 0.32s -bash asr tty4 1:32pm 17:22 1.04s 0.30s pine deb tty5 1:32pm 3.00s 1.22s 0.42s lynx ejr ttyp1 calvin 12:14pm 1:28m 1.33s 0.57s vi hairyspiders ejr ttyp0 calvin 1:02pm 1.00s 1.70s 0.24s w [ejr@hobbes ejr]$
The following lines, one per logged-in user, show
The login name
The tty name (the connection to the host)
The remote host name
The login time
Current idle time (that is, the time since a key on the keyboard was touched)
JCPU (job CPU time, or the total processing time for jobs on the current connection, which is the tty, for those into the jargon)
PCPU (process CPU time, or the processing time for the current process)
The command line of the current process
Whew! As you can see from Code Listing 7.11 and Code Listing 7.12, different systems' w commands produce slightly different (but similar) output.
Use w with grep to find information (slightly more abbreviated) about a specific user. For example, w | grep ejr gives limited information, but just about a specific user. See Chapter 1 for more information about piping commands.
Code Listing 7.12. w yields different information on different systems.
xmission> w 1:47pm up 38 day(s), 23:35, 36 users, load average: 1.58, 1.78, 1.75 ... ejraypts/16 Thu 6am1:14 -csh ...