topic Re: How to get the process id of a process? in Operating System - HP-UX

How to get the process id of a process?

Shashibhushan Gokhale — Tue, 20 May 2003 09:21:53 GMT

Hi,

I am trying to get the process id of a process I try to start in the background.

I had come to know about a technique of using $! to get the status of last spawned process.
The above method works for commands like sleep.

When I do $! for my program I get a value, but when I do ps -ef the process id for the process in the listing is greater than the value returned by $! by 1.
For additional information I am setting setsid() in my program. Does it has anything to do with it.

Can anyone help me out.

Thanks in advance.
Shashibhushan GOkhale

Re: How to get the process id of a process?

Ian Dennison_1 — Tue, 20 May 2003 09:31:47 GMT

Try using "$$" to obtain the current Process ID.

Null points if I am not the first to suggest this pse.

Share and Enjoy! Ian

Re: How to get the process id of a process?

Dietmar Konermann — Tue, 20 May 2003 09:33:32 GMT

Maybe your program does additional fork()s, e.g. to daemonize itself? In this case it would not be the "direct" child of your shell, i.e. no child the shell can know anything about.

Either you seek the process using ps or you add some code to the program that writes its own PID to some status file, just like syslogd uses /var/run/syslog.pid.

Best regards...
Dietmar.

Re: How to get the process id of a process?

Shashibhushan Gokhale — Tue, 20 May 2003 09:59:41 GMT

HI Dietmar,

You are absolutely right.
I am using fork() to daemonize itself.

Thanks,
Shashibhushan

Re: How to get the process id of a process?

Bill McNAMARA_1 — Tue, 20 May 2003 10:03:03 GMT

brise:root /# jobs
[2] + Running sleep 6000 &
brise:root /# jobs -p %2
21854

brise:root /# ps -ef | grep 21854
root 22308 21624 1 07:07:38 pts/tb 0:00 grep 21854
root 21854 21624 0 07:06:09 pts/tb 0:00 sleep 6000

Later,
Bill

Re: How to get the process id of a process?

Dietmar Konermann — Tue, 20 May 2003 10:11:14 GMT

Bill,
after running setsid() the program is the leader of a new process group. So I doubt, that jobs -p is able to find anything (didn't test this myself).

Best regards...
Dietmar.

Re: How to get the process id of a process?

John Meissner — Tue, 20 May 2003 10:12:27 GMT

to get the process number (pid) of a process you last ran try:

echo $!
or
echo $?

Re: How to get the process id of a process?

Bill McNAMARA_1 — Tue, 20 May 2003 10:22:41 GMT

okay Dietmar,
I just read the first line!