$ perl -lwe 'open STDOUT, ">&=6" or die ">&=6: $!"' >&=6: Bad file descriptor at -e line 1. $ perl -lwe 'open STDOUT, ">&=6" or die ">&=6: $!"' 6>/dev/null #### # Don't use this - DOESN'T WORK open my $to_child, ">&=6" or die ">&=6: $!"; open my $from_child, "<&=7" or die "<&=7: $!"; die "fork:$!" if not defined(my $pid = fork); if ($pid) { print $to_child "data for child\n"; my $ret = <$from_child>; } else { exec { "sub-program" } "sub-program", @args; }