The following code behaves just like it should (and like I said) for me:

corion@aliens:~/tmp$ cat test.pl
#!perl -w
use strict;

my $pid = open my $fh, 'sleep 1000 |'
    or die "Couldn't spawn: $! / $?";

print "Spawned child as $pid";
print "Doing own work $_\n" for 1..10;

print "Killing child $pid";
kill 9 => $pid;
print "done\n";
[download]

corion@aliens:~/tmp$ perl -w test.pl
Spawned child as 26868Doing own work 1
Doing own work 2
Doing own work 3
Doing own work 4
Doing own work 5
Doing own work 6
Doing own work 7
Doing own work 8
Doing own work 9
Doing own work 10
Killing child 26868done
[download]

I'm not sure what you're doing differently.

okay, I believe my problem was that I was redirecting my output, which causes open() to open the process in a shell. So the pid it was returning was the pid of the shell process.

remove the redirection, and it works.

sorry for all the hassle, I've sure learned a lot about processes though that I didn't know before on this little venture :-)

Actually I found another problem that was causing me confusion. I was closing the filehandle after opening it. (at your suggestion :-)) This was what was causing my script to not execute until after the app was closed, making me believe that it was not running in the background. I don't know why closing the filehandle would affect it this way though.

Try this: (after 10 sec the script will run)

#!/usr/bin/perl

use strict;

my $pid = open my $fh, 'sleep 10  |'
    or die "Couldn't spawn: $! / $?";
    
close $fh;

print "Spawned child as $pid";
print "Doing own work $_\n" for 1..10;

print "Killing child $pid\n";
kill 9 => $pid;
print "done\n";
[download]

ps: is it appropriate to call a process that runs in the background a "child"? It seems like it is disassociated from the "parent".

yes, you are right, it works.

I'll have to see what I was doing before.