#!/usr/bin/perl

my $command = "./program_to_run.pl";
my $fifo = "tmp.fifo";

system "mkfifo $fifo; $command >$fifo 2>&1 &";

open my $fh, "<", $fifo or die "Couldn't open fifo '$fifo': $!";
while (<$fh>) {
    print ": $_";
}
close $fh;
unlink $fifo;