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).
w
At the shell prompt, type w. You’ll usually see output much like that in Code Listing 7.11. The top line shows
The time
System uptime in days, hours, and minutes (uptime is how long it’s been since the system was restarted and is usually measured in weeks or months for Unix systems, as opposed to hours or days for personal computers).
The number of users
System load averages (the numbers indicate jobs—programs or scripts to execute—lined up to run in the past 1, 5, and 15 minutes)
[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]$
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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.
✓ Tip
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.
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
...
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