#! perl -slw
use strict;

our $WAIT ||= 10;

my $cmd = 'perl -e"$|++;sleep 1, print for 1 .. 10" |';
my $pid = open my $cmdFh, $cmd or die "Couldn't run '$cmd': $!";

sleep 1 while kill 0, $pid and $WAIT--;
kill 3, $pid and warn 'Command timed out' if $WAIT;

my $results = do{ local $/; <$cmdFh> };
print "Got: '$results'";