GeoServer extensions can be installed via the command line (shown below) or via Webmin File Manager.
Below, we are installing the MapFish Print Module:
$ su - tomcat
$ cd /tomcat/version/webapps/geoserver/WEB-INF/lib
$ wget http://sourceforge.net/projects/geoserver/files/GeoServer/2.11.1/extensions/geoserver-2.11.1-printing-plugin.zip
$ unzip -q geoserver-2.11.1-printing-plugin.zip
$ rm -f geoserver-2.11.1-printing-plugin.zip
* Be sure the extension you download matches your GeoServer version!
Restart Tomcat after installing any new extensions.
Note: some components, such as GDAL, require additional configuration.
Next: Read the manual
or jump to component pages below.
Important
Be sure to also view the sections below:
Moving the GeoServer Data Directory