you just gived me a reason to reboot into Windows XP :)

i found 2 ways of getting the PID of a process on a Windows XP system:

1. use the command tasklist (installed by Windows in %WINDIR%\system32) to get a table with details of the running processes on your system that you could easly parse

2. use Win32::Process::Info from CPAN to get more details

   #!perl
   
   use strict;
   use warnings;
   
   use Data::Dumper;
   use Win32::Process::Info;
   
   my $procs = Win32::Process::Info->new();
   print Dumper $procs->GetProcInfo();
   [download]

hope this helps...

Is the program there?

Yes

Actually IMHO these people do a tremendous job. Even though this isn't a perl solution. But it echos the sentiment of your plea for a win32-ps.

Here's another way using a semaphore.

#! perl -slw
use strict;
use Win32::Semaphore;

( my $semName = $0 ) =~s[\\][/]g;
die 'Program already running' if Win32::Semaphore->open( $semName );
my $sem = Win32::Semaphore->new( 1, 1, $semName ) or die $^E;
sleep 1000;
__END__
c:\test>start /b loner.pl

c:\test>loner.pl
Program already running at c:\test\loner.pl line 6.
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I've used the script's full pathname as the semephore name, with backslashes switched to forward slashes as the former are disallowed. If there is the possibility of multiply named copies of the script, then use a well-known name instead.

Oh. And don't let $sem or whatever you call yours go out of scope otherwise the system semaphore gets freed. Obvious I guess, but it hung me up for a while.

you could use Proc::PID_File to avoid running multiple instances of your script with a few lines of code.

but this does not work if someone starts the program in an alternate way.

googeling gave this link

Fortunately there's a simple solution that works on Unix and Windows:

#!perl -w
use strict;

use Fcntl qw(LOCK_EX LOCK_NB);
my $lockfile = "/someabsolutepath/writeabledirectory/lockfile";
open LOCKFILE, ">", $lockfile or die  "Cannot open lockfile\n";

if (!flock(LOCKFILE, LOCK_EX|LOCK_NB)) {
  print STDERR "Another copy of application is already running\n";
  exit(0);
}
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