Using Apache 2, you can see what modules are currently loaded by the HTTP daemon by running the following command:
-M option is really just a parameter passed to httpd.
apache2ctl is a front end to the Apache HyperText Transfer Protocol
(HTTP) server. It is
designed to help the administrator control the functioning of the Apache apache2 daemon.
NOTE: The default Debian configuration requires the environment variables APACHE_RUN_USER,
APACHE_RUN_GROUP, and APACHE_PID_FILE to be set in /etc/apache2/envvars.
The apache2ctl script returns a 0 exit value on success, and >0 if an error occurs. For
more details, view the comments in the script.