sub check_perm { my ( $mode, $perm ) = @_; if( defined $perm ) { return ( $perm =~ /^[0-7]{3}$/ ) ? oct( $perm ) : die "Malformed $mode mode $perm\n"; } return; } $opt_filemode = check_perm file => $opt_filemode; $opt_dirmode = check_perm directory => $opt_dirmode;