Process ID

Hi_This_is_Dev · 09-30-2009, 07:29 AM

On the first virtual console I have executed this command:

Code:

watch -d date

And then I am back here in terminal window:

Code:

[root@localhost ~]# ps -af
UID        PID  PPID  C STIME TTY          TIME CMD
root      5850  5821  0 17:37 tty1     00:00:01 watch -d date
root      6555  5799  0 17:56 pts/1    00:00:00 ps -af
[root@localhost ~]#

The underlines PPID 5821 is not in PID. Why?

Now let's have a look at this command:

Code:

[root@localhost ~]# ps -f
UID        PID  PPID  C STIME TTY          TIME CMD
root      5799  5796  0 17:36 pts/1    00:00:00 bash
root      6624  5799  0 17:58 pts/1    00:00:00 ps -f
[root@localhost ~]#

Here 5799 is in both PID and PPID.

sibaz · 09-30-2009, 08:24 AM

PPID is the Parent PID, so I've got a clean terminal running bash and I've run vi, then put it into the background, while I run some tests on the commandline.

If I look at all processes running with full columns, i get this:-
sbazley@mowgli:~$ ps -f
UID PID PPID C STIME TTY TIME CMD
sbazley 4118 4084 0 Sep28 pts/2 00:00:00 /bin/bash
sbazley 15849 4118 0 14:16 pts/2 00:00:00 vi
sbazley 16099 4118 0 14:21 pts/2 00:00:00 ps -f

so you can see vi and ps -f are both processes who's parent is 4118, which is bash. If I grep for 4084 I get this:-

sbazley@mowgli:~$ ps ax |grep 4084
4084 ? Rl 1:49 konsole -session 101b719b1bd112000125308850900000036980014_1253177575_354018

Which shows bash was started by konsole, which is the KDE terminal program I'm using.