use strict;
use warnings;
use Win32::Process;
use Win32;
use threads;

my $ProcessObj;
Win32::Process::Create($ProcessObj,
                            "C:\\windows\\system32\\calc.exe",
                            "",
                            0,
                            NORMAL_PRIORITY_CLASS,
                            ".")|| die ErrorReport();

print "process created\n";
$| = 1;
sub ErrorReport{
    print Win32::FormatMessage( Win32::GetLastError() );
}

sub wait_proc {
  $ProcessObj->Wait(INFINITE);
  print "process finished\n";
}
my $thr = threads->create('wait_proc');


print "waiting for input\n";
$_ = <>;
print "input is $_\n";

$thr->join;
[download]

Thanks, that's a good idea, but íf I want to fork a number of childs I would need one thread per child for your approach which I think is costly.

How 'bout this:

use strict;
use warnings;
use Win32::Process;
use Win32::IPC 'wait_any';
use Win32;
use threads;
my @progs = (
 'C:\windows\system32\calc.exe',
 'C:\windows\system32\notepad.exe',
);
my @proclist;
my %proctable;

for (@progs) {
  my $ProcessObj;
  Win32::Process::Create($ProcessObj,
                  $_,
                  "",
                  0,
                  NORMAL_PRIORITY_CLASS,
                  ".")|| die ErrorReport();

  $proctable{$ProcessObj->GetProcessID}{progname} = $_;
  print "process created for $_\n";
  push @proclist, $ProcessObj;
};

$| = 1;
sub ErrorReport{
    print Win32::FormatMessage( Win32::GetLastError() );
}

sub wait_procs {
  while (@proclist) {
    my $x = wait_any(@proclist, INFINITE);
    if ($x) {
      my $proc = splice(@proclist, abs($x) - 1, 1);
      my $id = $proc->GetProcessID;
      my $program = $proctable{$id}{progname};
      print "process finished x=$x id=$id program=$program\n";
    }
  }
  print "thread exit\n";
}

my $thr = threads->create('wait_procs');


print "waiting for input\n";
$_ = <>;
print "input is $_\n";

$thr->join;
[download]

use Win32::Process;
use Win32;

my $ProcessObj;

my $worked = Win32::Process::Create (
   $ProcessObj,            # Process object 
    "C:\\myprog",          # full path name of child program 
   "C:\\myprog arg",       # command line 
    0,                     # inherit handles boolean
    NORMAL_PRIORITY_CLASS, # Creation flags
     ".");                 # working directory of child

die 'Error: '.Win32::GetLastError() unless $worked;

# Do some stuff

$ProcessObj->Wait(INFINITE);   # Wait for completion

my $ExitCode;
$ProcessObj->GetExitCode($ExitCode)    # Get child result
[download]

Thanks - but your Wait will block the parent process until the child exits - or does it not?

What I want is a way to have parent and child run concurrently with the parent being informed about the child exit.

Fair enough, in that case use $ProcessObj->GetExitCode($var) which will return STILL_ACTIVE if it is,um, still active. You will need use Win32::Process qw(STILL_ACTIVE); for that.

I am not sure if this module will help you - but have you looked at Win32::Job

The watch method might be able to be used to get the status of your process when it exits. But then again - this might be what you are trying to avoid - polling.