PHP exec - check if enabled or disabled

This will check that exec is available and enabled BEFORE trying to run it. If you run exec() and the function does not exist or is disabled a warning will be generated. Depending on the server settings that may render to the browser and will almost-always write a line to a log file = performance hit.

// Exec function exists.
// Exec is not disabled.
// Safe Mode is not on.
$exec_enabled =
   function_exists('exec') &&
   !in_array('exec', array_map('trim', explode(', ', ini_get('disable_functions')))) &&
   strtolower(ini_get('safe_mode')) != 1
;


if($exec_enabled) { exec('blah'); }

if(function_exists('exec')) {
    echo "exec is enabled";
}

ini_get('disable_functions')

What you actually want to do is use ini_get('disable_functions') to find out if it is available to you:

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

Answered on stackoverflow here: Check if "exec" is disabled, Which actually seems to come from the PHP Man page: http://php.net/manual/en/function.exec.php#97187

Path

If the above returns true (you can use exec()), but PHP can still not trigger the script there is a good chance that you have a path issue for that script, test this by doing:

print exec('which bash');

and then try

print exec('which ogr2ogr');

This will check if the function actually works (permissions, rights, etc):

if(@exec('echo EXEC') == 'EXEC'){
    echo 'exec works';
}