3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php var_dump(shell_exec('free -m'));
Output for 5.0.0 - 5.3.28, 5.4.0 - 5.4.26, 5.4.44 - 7.1.0
NULL
Output for 5.3.29, 5.4.27 - 5.4.43
NULL sh: 1: free: not found
Output for 4.3.0 - 4.4.9
string(0) ""