Most ikiwiki plugins are perl modules and should be installed somewhere in
the perl module search path. See the @INC list at the end of the output of
perl -V for a list of the directories in that path. All plugins are in
the IkiWiki::Plugin namespace, so they go in a IkiWiki/Plugin subdirectory
inside the perl search path. For example, if your perl looks in
/usr/local/lib/site_perl for modules, you can locally install ikiwiki
plugins to /usr/local/lib/site_perl/IkiWiki/Plugin
You can use the libdirs and/or libdir configuration options to add
directories to the
search path. For example, if you set libdir to /home/you/.ikiwiki/,
then ikiwiki will look for plugins in /home/you/.ikiwiki/IkiWiki/Plugin.
Ikiwiki also supports plugins that are external programs. These are
typically written in some other language than perl. Ikiwiki searches for
these in /usr/libexec/ikiwiki/plugins by default. If libdirs or libdir are
set, it will also look under those directories, for example in
/home/you/.ikiwiki/plugins.
Note that this type of plugin has to be executable for ikiwiki to use it.