Hi,
I'm attempting to build a pmfl type interface to manage some
processes.  Such as monitoring their status, and having the option to
kill/restart them.  I'm looking for a generic way to capture the PID
of each process that I'm running.  Normally I would do something like:

system("sh -ic \"((program_executable > Debug &) 2>&1) >
/tmp/PID\" > /dev/null 2>&1");

This would redirect the debug output to a file called 'Debug' and
redirect the pid to a file called 'PID', which I can then read in.

However, now I want to be able to run the program inside an xterm so
that I can see the debug in realtime.  Something like:

system("sh -ic \"xterm +wf -hold -e program_executable &\">
/dev/null 2>&1 > /tmp/PID");

The problem with this setup is that I successfully retrieve the pid
for the xterm, but I've been unable to get the pid for the
program_executable.

Does anyone have any ideas on how I might modify the above to return
BOTH the xterm PID to a file and the program_executable PID to another
file?  Or perhaps you can think of a better way to get access to this
info.  I thought of doing some "ps -ef | grep" type command to get the
PID, but thought I might run into some problems if I had multiple
processes running with the same name.

Thanks in advance for all of your ideas!

Dennis

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Dennis wrote:
> Hi,
>   I'm attempting to build a pmfl type interface to manage some
> processes.  Such as monitoring their status, and having the option to
> kill/restart them.  I'm looking for a generic way to capture the PID
> of each process that I'm running.  Normally I would do something like:
>
>        system("sh -ic \"((program_executable > Debug &) 2>&1) >
> /tmp/PID\" > /dev/null 2>&1");
>
> This would redirect the debug output to a file called 'Debug' and
> redirect the pid to a file called 'PID', which I can then read in.
>
> However, now I want to be able to run the program inside an xterm so
> that I can see the debug in realtime.  Something like:
>
>        system("sh -ic \"xterm +wf -hold -e program_executable &\">
> /dev/null 2>&1 > /tmp/PID");
>
> The problem with this setup is that I successfully retrieve the pid
> for the xterm, but I've been unable to get the pid for the
> program_executable.
>
> Does anyone have any ideas on how I might modify the above to return
> BOTH the xterm PID to a file and the program_executable PID to another
> file?  Or perhaps you can think of a better way to get access to this
> info.  I thought of doing some "ps -ef | grep" type command to get the
> PID, but thought I might run into some problems if I had multiple
> processes running with the same name.
>
> Thanks in advance for all of your ideas!
>
> Dennis

For capturing program output directly, look at the command popen().
However, you cannot know the pid of a program run under the system()
command because when system returns, the program has already completed
execution.  Probably the best alternative is to fork() and exec() the
program yourself, and create a pipe() connected to the program's stdin
and stdout yourself.  This is how a shell program does this.

--

Fletcher Glenn

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