Does anyone know how can we shell_exec() in a Computed Field?

$command = "some_command_here";
$node_field[0]['value'] = shell_exec($command);

Does not seem to work.

Comments

What does it do? It is

What does it do?

It is possible shell_exec() is disabled().

It is possible the command passed in not correct?

Tried the exact command on

Tried the exact command on SSH and its working perfectly.

Update: Looks like my problem is out of the scope of CF and Drupal. I thinks it has something to do with permission.