How to check which apache modules are enabled/installed?

You're on Ubuntu so try:

apache2ctl -M

httpd -M will tell you which modules are built-in or shared.

Edit 2023: WARNING - use this with caution. See below.

Nothing from the answers above works if you can’t run commands on a remote server. If you have only “user” privileges or none at all try creating a test.php script:

<pre>
<?php
print_r(apache_get_modules());
?>
</pre>
    

Though, it will only work if PHP is installed as mod_php.

To explain warning part - seeing this to gain some popularity over the years I feel obligated to ask to look at the first comment below.

In short - exposing this information in public my hurt you. So any *.phpfile created for this trick should have random/hard-to-guess name and be deleted as quickly as possible after gathering neccessary info.

Maybe this will help for some people on shared hosts with no access to httpd, apachectl or processes:

Enabled modules: ls /etc/apache2/mods-enabled/

Available modules: ls /etc/apache2/mods-available/

You can also use apachectl

apachectl -t -D DUMP_MODULES