Try IPC::Run (in general everytime you think you need a better interface to external program execution then offered by Perl builtins you should use IPC::Run).

# UNTESTED CODE

use IPC::Run qw(start);

my $h = start([qw(prog1 file1)],
              '|',
              [qw(filter -v), $version],
              "> $tmpfile", "2>&1");
$h->finish;

# returns exist values of each child process which you can use
# to find signal that killed each child process
my @results = $h->full_results;
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--
Ilya Martynov, ilya@iponweb.net
CTO IPonWEB (UK) Ltd
Quality Perl Programming and Unix Support UK managed @ offshore prices - http://www.iponweb.net
Personal website - http://martynov.org