Proc::Background was exactly the wrapper I needed. Mille grazie.

#!/usr/bin/perl -w
use strict;
use Proc::Background;

my $pid1 = Proc::Background->new("cd /tmp ; pwd > testplpwd ; sleep 100");

for (my $i=0; ; ++$i) {
    print STDERR "$i: Your pid $pid1 is ".($pid1->alive())."\n";
    ($pid1->alive()) or last;
    sleep(1);
}

/iaw