Check if "exec" is disabled [duplicate]

Is there any function in PHP that I can use to detect whether or not the exec function is available?

<?php
function exec_enabled() {
  $disabled = explode(',', ini_get('disable_functions'));
  return !in_array('exec', $disabled);
}
?>

EDIT: Fixed the explode as per Ziagl's comment.

The following function is more robust. It deals with the disabled_functions value having 0 or more spaces between function names, checks the suhosin patch's blacklist setting, covers safe_mode, and stores the answer for future reference.

function is_exec_available() {
    static $available;

    if (!isset($available)) {
        $available = true;
        if (ini_get('safe_mode')) {
            $available = false;
        } else {
            $d = ini_get('disable_functions');
            $s = ini_get('suhosin.executor.func.blacklist');
            if ("$d$s") {
                $array = preg_split('/,\s*/', "$d,$s");
                if (in_array('exec', $array)) {
                    $available = false;
                }
            }
        }
    }

    return $available;
}

You can search the ini setting disable_functions for the exec() function.

if( false !== strpos(ini_get("disable_functions"), "exec") ) {
 // exec() is disabled

Just for completeness, note that PHP Safe Mode puts some restrictions on the function too.

You also need to check whether safe_mode is active as exec is unavailable if safe_mode is on

function is_exec_available() {

    // Are we in Safe Mode
    if ( $safe_mode = ini_get( 'safe_mode' ) && strtolower( $safe_mode ) != 'off' )
        return false;

    // Is shell_exec disabled?
    if ( in_array( 'exec', array_map( 'trim', explode( ',', ini_get( 'disable_functions' ) ) ) ) )
        return false;

    return true;

}