Miscellany

#!/usr/local/bin/php
<?php

define('READ',4);
define('WRITE',2);
define('EXEC',1);

$modes = array(READ, WRITE, EXEC);

if($argc != 2) usage();
if(strlen($argv[1]) != 3) usage();
if(preg_match('/\D/',$argv[1])) usage();

$input = str_split($argv[1]);
foreach($input as $uno) {
 if($uno > 7) usage();
 foreach($modes as $mode) {
  $result .= $mode & $uno ? 1 : 0;
 }
}

print $result."\n";

function usage() {
 $usage = "usage: {$_SERVER['_']} [octal mode]\n";
 fwrite(STDERR, $usage);
 exit(1);
}

?>