PS-Process Status
From http://www.linux.ie/newusers/beginners-linux-guide/ps.php
1. What does 'ps'mean?
ps is the shortage for Process Status. The command should be used to display the currently running processes on Unix/Linux systems. If you know the 'Task-Manager' which pops up under Windows NT/2000/XP when you press CTRL+ALT+DEL then you have a clue what ps does under Unix/Linux. Ps can show you the running processes on your system in different ways. I will describe the basic ones you should know.2. Why is it good to know how the ps command works?
If you have a process which seems to hang (e.g. netscape navigator on some buggy websites) and you want to stop the process, then you can determine the process id of the process. Why do you need the process id? You can stop the process with the help of the 'kill' command. The kill command needs a process number otherwise it won't know to which process it should send the 'kill' signal. Other example. You have started a process and now your machines becomes slower and slower. You stop the process but your machine still gets slower and slower. Now it will be helpful if you can stop the process. In this case you also need its pid.Next example: You want to know what processes your friend just uses (you know he has an remote session open), then you can also use the ps command to find out which processes belong to him.
3. Some examples for the ps command
3.1. Executing the ps command
just enter ' ps' at the prompt:$ ps PID TTY TIME CMD 3511 pts/1 00:00:00 bash 3514 pts/1 00:00:00 ps
3.2. Displaying all processes owned by a specific user
$ ps ux USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND heyne 691 0.0 2.4 19272 9576 ? S 13:35 0:00 kdeinit: kded heyne 700 0.1 1.0 5880 3944 ? S 13:35 0:01 artsd -F 10 -S 40 heyne 710 0.0 2.8 21876 11072 ? S 13:35 0:00 kdeinit: knotify heyne 711 0.0 0.0 1344 352 ? S 13:35 0:00 kwrapper ksmserve heyne 713 0.0 2.4 18900 9304 ? S 13:35 0:00 kdeinit: ksmserve heyne 714 0.0 2.9 21548 11528 ? S 13:35 0:00 kdeinit: kwin -se heyne 715 0.3 4.8 31096 18820 ? S 13:35 0:03 /usr/lib/mozilla/ heyne 719 0.1 3.5 22548 13680 ? S 13:35 0:01 kdeinit: kdesktop heyne 721 0.5 3.6 23904 14028 ? S 13:35 0:05 kdeinit: kicker heyne 722 0.0 2.0 18504 7824 ? S 13:35 0:00 kdeinit: kio_file heyne 723 0.0 4.8 31096 18820 ? S 13:36 0:00 /usr/lib/mozilla/ heyne 724 0.0 4.8 31096 18820 ? S 13:36 0:00 /usr/lib/mozilla/ heyne 725 0.0 4.8 31096 18820 ? S 13:36 0:00 /usr/lib/mozilla/ heyne 729 0.0 2.4 19408 9404 ? S 13:36 0:00 kdeinit: klaptopd heyne 730 0.0 2.3 17044 9152 ? S 13:36 0:00 kteatime -session heyne 731 0.0 3.0 21236 11848 ? S 13:36 0:00 kdeinit: kmix -se heyne 735 0.0 4.8 31096 18820 ? S 13:36 0:00 /usr/lib/mozilla/ heyne 736 0.0 2.7 20492 10600 ? S 13:36 0:00 korgac --miniicon heyne 745 0.0 2.4 19232 9528 ? S 13:36 0:00 kalarmd --login heyne 753 0.0 0.3 2108 1160 pts/0 S 13:36 0:00 bash heyne 787 0.7 1.7 9520 6784 ? S 13:50 0:00 emacs heyne 789 0.2 0.3 2112 1164 pts/1 S 13:51 0:00 bash heyne 794 0.0 0.4 3560 1576 pts/1 R 13:51 0:00 ps ux
You can also use the syntax " ps U username". In my case I use ps U heyne. If you use this syntax you get a result like the following:
PID TTY STAT TIME COMMAND 721 ? S 0:08 kdeinit: kicker 722 ? S 0:00 kdeinit: kio_file file /tmp/ksocket-heyne/klauncherx8 723 ? S 0:00 /usr/lib/mozilla/mozilla-bin 724 ? S 0:00 /usr/lib/mozilla/mozilla-bin 725 ? S 0:00 /usr/lib/mozilla/mozilla-bin 729 ? S 0:00 kdeinit: klaptopdaemon -session 11c0a8021400010381450 730 ? S 0:00 kteatime -session 11c0a802140001038168018000001282500 731 ? S 0:00 kdeinit: kmix -session 11c0a8021400010368648780000000 735 ? S 0:00 /usr/lib/mozilla/mozilla-bin 736 ? S 0:00 korgac --miniicon korganizer 745 ? S 0:00 kalarmd --login 753 pts/0 S 0:00 bash 787 ? S 0:01 emacs 789 pts/1 S 0:00 bash 796 ? S 0:07 kdeinit: konqueror --silent 800 ? S 0:00 kdeinit: kio_uiserver 801 ? S 0:02 xmms /files/mp3/00's/Badly Drawn Boy-About a Boy-03-S 802 ? S 0:00 xmms /files/mp3/00's/Badly Drawn Boy-About a Boy-03-S 803 ? S 0:00 xmms /files/mp3/00's/Badly Drawn Boy-About a Boy-03-S 804 ? S 0:00 xmms /files/mp3/00's/Badly Drawn Boy-About a Boy-03-S 837 ? S 0:00 xmms /files/mp3/00's/Badly Drawn Boy-About a Boy-03-S 838 ? S 0:00 xmms /files/mp3/00's/Badly Drawn Boy-About a Boy-03-S 860 pts/1 R 0:00 ps U heyneAs you can see, the ps command can give you a lot of interesting information. If you for example want to know what your friend actually does, just replace your login name with her/his name and you see all processe belonging to her/him.
3.3. Own output format
If you are bored by the regular output, you could simply change the format. To do so use the formatting characters which are supported by the ps command.If you execute the ps command with the 'o' parameter you can tell the ps command what you want to see:
e.g.
Odd display with AIX field descriptors:
$ ps -o "%u : %U : %p : %a" RUSER : USER : PID : COMMAND heyne : heyne : 3363 : bash heyne : heyne : 3367 : ps -o %u : %U : %p : %a
4. Further reading
If you need further informations about the ps command just look into the famous man pages of your linux installation.
$ man ps By Henning Heyne.
PS:
ps -af|grep node #Find process using string match
kill -9 processid #Kill process in high permission