What are the potential reasons for a shell_exec command with a specific path not working in PHP?

The potential reasons for a shell_exec command with a specific path not working in PHP could include incorrect permissions on the file or directory, the path being incorrect or inaccessible, or the command itself not being allowed by the server configuration. To solve this issue, ensure that the file or directory has the correct permissions, double-check the path for accuracy, and verify that the command being executed is allowed by the server.

$output = shell_exec('/full/path/to/your/command');
echo $output;