Shell Programming and Scripting

Hi,

I run a command in the shell that run another process. I need a way to provide the command's pid to the subprocess. For instance, if I run the command foo:

Code:

foo process_to_run -p foo's_pid

I would like to pass to process_to_run the pid of the foo command, or something that link process_to_run to foo.
I would like to access to foo from process_to_run

Is there any way to do that?
Thanks
D

That's an interesting request. It's hard to know your PID in advance!

But not impossible: The exec command can be used to replace your shell's PID with a command. The process being executed will change but the PID won't.

So if you do this inside its own independent little shell script, it should be doable like this:

Code:

#!/bin/sh

exec foo process_to_run -p $$
# Unless exec fails somehow, no commands below here will be run.
# The shell will no longer exist, having been replaced by foo!
echo "exec failed code $?" >&2
exit 1

Where $$ is the shell's PID. Since we're running foo with exec, the shell will be replaced with foo, and have the precise same PID as it when all is said and done.

That's great!

Thanks a lot