I want to stop a process from running but I dont know which process is suitable to be killed cause I'm afraid that if I stop the wrong process, it might make the system unstable. Any suggestion on stopping a process? Is it wise to stop a process from the /usr or /sbin directory which is runned by root?

If you know the name of the process, eg sendmail, just type ps -aux | sendmail, and that will list all processes with sendmail in the name, along with their PIDs (process id's).
then just kill the process by number. ie if it's pid 567, just kill 567 will do it.
if you want to get a list of al the processes runing, and then sit down and pore over it, type 'ps -aux > processes.txt
That will send a detailed list of all the processes to the file processes.txt
then you can print it, and try to work out what each is/does.
if you see a process called xyz, look for a man page for that program . 'man xyz' will do that. That will get you info on most of the stuff that's running, and you can decide which ones you need/don't.

Anything you want to stop from loading at bootup, remove the S* file from /etc/rc.d.rc3.d (to see the names of the files kicked off at startup, type 'ls -l /etc/rc.d/rc3.d/S*' ie list all the files, that start with S, in that directory.
Or if you are running X, use the services program to select which ones you want/don't want.

Does this help?

Griffo

If you don't know WHICH process you want to stop, then how do you know that you want to stop something?? What problem are you trying to solve......

if you do "ps" you will see all the processes. (see man ps) If you don't know what something is, then you can bet that killing it might not be good. On the other hand, you probably won't do irreversible damage by experimenting (After backing up all your data, of course... )

How about this for a notion.....

If you are a Good Guy, you are not running as super user (root), right!?

Thus you can kill all and every process in sight.

And the system will keep running.

Since the kernel won't allow you to kill any process that is not your user process.


Your window manager may die, your editor may get killed, the panel may vanish but who cares, the system keeps chugging along.

Logout and login again and all is fine.


Useful commands relating to processes....

ps auxw | less
List all processes


pstree -pal
List process tree structure.

top
See which process is hogging

killall -9 firefox-bin
Tries to kill all firefox instances.

su
/etc/init.d/httpd restart
exit
Kills and restarts the web server.