Leia perldoc -f open
e faça algo como:
open(P, "/bin/date --date=\"$since\" '+%Y,%m,%e' |" ) || die "can't fork: $!";
while (<P>) {
chomp;
$tmp = $_;
$tmp =~ s/,0/,/; # remove %m leading zero for months less than 10.
@base = split /,/, $tmp, 4;
if ( $#base != 2 ) { # only expect 3 fieds from /bin/date
die "Cannot parse \"$since\" with /bin/date\n";
}
}
close P || die "bad /bin/date";
}