What Is The Computer Doing?

ps

The ps command displays information about the processes that are currently running on the computer system. ps stands for process statistics.

UNIX is a multi-tasking tasking operating system, and is always doing something. When the UNIX operating system is performing a task, there is always at least one process associated with that task.

"Process" A software program that is executing on a UNIX system at a given instant in time.

An example would be the who command. When you type who at the command line, your process exists on the operating system for as long as it takes for the who command to run. When the who command finishes, and you are returned to your prompt, the process no longer exists.

$ ps

  PID    TTY     TIME  COMD
 19304  pts004   0:00  ps
 19286  pts004   0:00  sh

$ _

ps, by itself, shows you information about only your processes. To learn more about all of the processes that are running, use the -ef options with the ps command.

$ ps -ef

 UID   PID  PPID  C    STIME TTY      TIME COMD
root     0     0  0   Mar 18 ?        0:01 sched
root     1     0  0   Mar 18 ?        1:09 /sbin/init
root     2     0  0   Mar 18 ?        0:22 pageout
root     3     0  0   Mar 18 ?        4:21 fsflush
root   286   279  0   Mar 23 ?        0:08 /usr/lib/saf/ttymon
root   279     1  0   Mar 23 ?        0:04 /usr/lib/saf/sac -t 300
root   262     1  0   Mar 23 ?        0:02 /usr/X/bin/xdm
root   164     1  0   Mar 23 ?        5:03 /usr/sbin/sapd
aja1 11687   262  0 16:37:28 ?        1:10 /usr/X/bin/xdm
aja1 17764 11687  0 07:57:51 ?        0:03 -wksh
root   288   279  0   Mar 23 ?        0:05 /usr/lib/saf/ttymon
aja1 17867 17866  0 08:08:47 pts/2    0:04 wksh
root   344     1  0   Mar 23 ?        0:01 /usr/lib/lpsched
root   326     1  0   Mar 23 ?        5:25 /usr/sbin/cron
aja1 17788 17784  0 07:58:50 ?        0:02 /bin/mailx -N -f /
root   333     1  0   Mar 23 ?        0:00 /usr/sbin/cs
root   351   344  0   Mar 23 ?        0:00 lpNet
aja1 17770 17764  0 07:57:55 ?        1:30 /usr/X/bin/dtm -motif
aja1 18154 18144  0 08:40:05 pts/3    0:03 wksh
aja1 18333 18154  0 09:03:40 pts/3    0:00 wksh
stu1 19305 19286 31 10:58:19 pts/4    0:01 ps -ef
stu1 19207 17867  0 10:52:50 pts/2    0:01 -ksh
stu1 19286 19285  0 10:56:48 pts/4    0:00 /bin/sh
stu1 19284 19207  0 10:56:48 pts/2    0:00 script

$ _
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