How does the PHP configuration setting save_mode affect the execution of commands like exec() or system()?

The PHP configuration setting `safe_mode` restricts the execution of certain functions like `exec()` or `system()` for security reasons. If `safe_mode` is enabled, these functions may be disabled altogether or restricted to only certain directories. To allow the execution of these functions, `safe_mode` must be disabled in the PHP configuration.

// Disable safe_mode in PHP configuration
ini_set('safe_mode', 0);