My idea was "somehow" to save reference to an object I get by Win32::Process::Create and later use this reference in another script.

It won't work.

Update:

To elaborate. If you "store" a system handle given to one process, in some persistent storage, and then try to retrieve that handle and use it from another process some time after the first process has ended, the handle will be invalid.

Ie. It won't work.

Think about a different approach. Windows is a painful environment, but it has an API for background processes. They are called services, and it is possible to write services in Perl. Services can be monitored easily and with a predefined API. No need to re-invent the wheel.

On a Unix system, I would (and do) use daemontools to run and monitor "background" processes, with much less pain. Should a process exit unexpectedly, daemontools will report that and restart the process (unless configured otherwise), thanks to SIGCHLD.

Windows has no signals, not even SIGCHLD, but you can (painfully) construct similar mechanisms, typically using atoms, semaphores, and other API functions not originally intended to do so.

The important trick in both cases is that the script starter does not exit, but keeps track of its child processes. With daemontools, you don't even start the child process, but instead tell the monitor to start (or stop or signal) the script. This is very similar to how Windows Services behave.

Alexander

Its amazing how often the answer to a question is right in the docs

Thank all of you for advice. Win32::Process::Open seem to be very promissing, only that I do some mistake. I have writen 2 short scripts:

# SCRIPT TO START NOTEPAD.EXE
#!/usr/bin/perl -w

use Win32;
use Win32::Process;

$ApplicationName = 'c:\\windows\\notepad.exe';
$CommandLine = 'notepad';

$CreateOptions = NORMAL_PRIORITY_CLASS | DETACHED_PROCESS;
Win32::Process::Create($ProcessObj,$ApplicationName,$CommandLine,
    0, # Don't inherit.
    $CreateOptions,
    ".") # current dir.
    or die print_error();

#$ProcessObj->Wait(INFINITE) or warn print_error();
$ProcessObj->Wait(500) or warn print_error();

$ProcessObj->GetExitCode($ExitCode) or warn print_error();

print "[$CommandLine] exited with $ExitCode\n";

sub print_error {
    print Win32::FormatMessage( Win32::GetLastError() );
}

$pid = $ProcessObj->GetProcessID();
print "PID: $pid\n\n";


> PID: 3052
>
[download]

*******************************************************************************

The PID I get from the running process I pass to the second script:

# SCRIPT TO CHECK RUNNING PROCESS
#!/usr/bin/perl -w
use Win32;
use Win32::Process;

$pid = shift;

Win32::Process::Open($ProcessObj,$pid,1); 

$ProcessObj->Wait(INFINITE) or warn print_error();

print "END \n";

$ProcessObj->GetExitCode($ExitCode) or warn print_error();
print "...exited with $ExitCode\n";
sub print_error {
    print Win32::FormatMessage( Win32::GetLastError() );
}
[download]

----------------------------------------------------------------------------------

Unfortunately I get this message:

>PID: 3052
>
>Access is denied.
>
>END 
>...exited with 259
[download]

*******************************************************************************

Have you any idea why I keep getting the massage: Access is denied?

I was thinking about windows services as afoken has suggested as well. I need to start about 20000 processes in about 12 hours with about 100 types of command lines - perl scripts, BAT scripts, executables. Some of them run few seconds, some of them run few hours. Is stil this type of tasks suitable to run via Win32::Daemon?

Thanks

Tomas