[SOLVED] Getting porcess id

killasmurf · 2 July 2008 18:29

Is there a way to get Process ID when i start app? How?
If that would be possible, i could make some wonderful things…

thomasadam · 2 July 2008 18:36

DestroyFunc PidFeedback
AddToFunc   PidFeedback
+ I UnsetEnv pid
+ I PipeRead `echo exec $0 && echo SetEnv pid $$$$`
+ I SomethingThatUses $[pid]

PidFeedback xcalc

– Thomas Adam

killasmurf · 2 July 2008 18:48

That was very fast, thanks…
Also one more question on this matter:
Is there a way to get pid of already running app?

thomasadam · 2 July 2008 18:58

DestroyFunc PidOfSomething
AddToFunc   PidOfSomething
+ I UnSetEnv pid$0
+ I PipeRead `echo SetEnv pid$0 $(pidof $0)`
+ I DoSomethingWith $[pid$0]

PidOfSomething somerunningapplicationname

– Thomas Adam

killasmurf · 2 July 2008 19:52

On IRC

Hello!
I need a tip
Here’s what i wanna do (i just don’t know yet hot to do it)
I want FVWM at startup/restart to check if mplayer is running or not
if not, then start mplayer in slave mode
viewtopic.php?f=33&t=2092
<thomas_adam> killasmurf: AddToFunc StartFunction I Test (init) Exec exec pidof mplayer || mplayer -options
Why do you use Exec exec, when you can simply use Exec?
I noticed this in all forum posts
<thomas_adam> The second exec puts it outside the process group of FVWM, so FVWM never waits for the return of the initial exec - and hence doesn’t spawn as many shells left dandling from an explicit command. Remember the first Exec (note the caps) is a command to FVWM; the second exec (in lowercase) is to the shell. Confer ExecUseShell of course.
thomas_adam >>> Ok, that probably also explains how to make mplayer stop spamming my ~/.xsession-errors, i currently redirect mplayer’s output to /dev/null. lol

EDIT:
On IRC

nemesis9 · 24 July 2008 16:13

thomasadam:

killasmurf:

Is there a way to get Process ID when i start app? How?
If that would be possible, i could make some wonderful things…
DestroyFunc PidFeedback
AddToFunc   PidFeedback
+ I UnsetEnv pid
+ I PipeRead `echo exec $0 && echo SetEnv pid $$$$`
+ I SomethingThatUses $[pid]
PidFeedback xcalc
– Thomas Adam

I’m not getting this to work correctly. I want SomethingThatUses to be a C program that takes a pid argument.
I’ve tried:

I Exec c_program $[pid]
I c_program $[pid]
I Exec exec c_program $[pid]

The C program always reads the environment variable and the argument as just a $

thomasadam · 24 July 2008 17:37

Bloody BBCode…

The PipeRead line wants five $$$$$ in it not four:

+ I PipeRead `echo exec $0 && echo SetEnv pid $$$$$`

(Hopefully that line above renders OK.)

– Thomas Adam

nemesis9 · 24 July 2008 18:20

Thanks, now my C program is getting the pid. However, I noticed the following behavior.

I applied the PidFeedback function to xterm. When the C program is called it has the process id not of the xterm, but likely the PipeRead process? For example, I launch xterm and a ps shows the new xterm has a process id of 5851, but the C program is getting 5850. The xterm has a ppid of 5037, which is fvwm’s process id.

Thanks,
Tony

Gramphos · 8 August 2008 12:42

That is to be expected the way it is written above. To get around that you need to do some trick to start a background process from within the PipeRead, and get the pid of that process, and then exec the xterm from it.

This can be done using a wrapper script. (it might be possible without also)
pid_wrapper:

#/bin/bash
echo $$
exec "$@" 1>&-

(Note that it is important to close stdout on the exec, or PipeRead won’t return)

and then change the PipeRead to

PipeRead "echo SetEnv pid `(pid_wrapper $*)&`"