It’s really common to want to review your php setup. The easiest way is the php function phpinfo(); the following will run from the command line or from a web browser:
<?php
phpinfo();
?>
Or to just see the modules
<?php
phpinfo(INFO_MODULES);
?>
To run from the command line type
php textfile_name
Since outputting this information can be a security risk avoid running from your webserver unless the directory is secured against random visitors.