I think you can't, directly. You could have your process write out it's pid to a file, and read it from your perl script - but since execution won't resume on the perl script anyway, until the process has ended, it's PID will be meaningless.

It's possible that you can do something with fork and exec:

perl -le '
  if ($pid=fork) {
    print "pid: $pid"; 
    exit;
  }
  exec ("echo new pid: \$\$");
'
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-- Dan

Update: Thanks to dws (++!), I stand corrected.

I'm not convinced that you'll be able to get the PID of the command which is being exec()'d. Sure, fork() returns it's PID to the parent, but that's still only given you the PID of the perl process that is going to be doing the exec("command"), not the PID of command itself.

I've had a quick look at IPC::Open3 - it returns the PID of the child process, but I'm not sure if it's the fork()'ed perl process, or the external command.
Unfortunately I've not got time to look in that further right now - it is left as an exercise for the reader :-)

Cheers,

BazB

I'm not convinced that you'll be able to get the PID of the command which is being exec()'d.

exec() doesn't change the process id.

In Unix, I believe it's

ps -ef | grep 'foo.exe'

ps is the unix command to list processes currently running. The switch -ef shows extended information for all processes currently running for all users. If the program is running under your username, then just use ps with no options and you'll have less to sort through.

This is assuming the process is still running in the background and you have access to a command prompt.

Rather than using a system call to ps and grep, you could do the whole thing in perl using Proc::ProcessTable.

BazB