http://www.spip.net/en_article3475.html
A plugin is a programme which enhances or adds new features to SPIP.
It is written specifically for SPIP and respects a particular
formalism (an API) that allows SPIP to interact with it. The name
"plugin" indicates that it is easy to plug into and unplug from SPIP.
The plugins system is a way to avoid the SPIP's "kernel" growing too
large. It makes for easier maintenance and opens wider possibilities
for customisation.
Since SPIP 1.9, it has been possible to install such plugins into SPIP.
Getting and Installing a "plugin"
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A plugin is self-contained in a folder that bears its name and holds
all its files.
To install a plugin, you only need to copy its folder to the /plugins
folder at the root of your site. The /plugins folder will not be
created when installing SPIP, you need to create it yourself. To keep
them tidy, you can also install plugins within sub-folders of the
/plugins folder.
Activation of a plugin
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In the private area, you will find a sub-menu "Manage plugins" under
the "Configuration" menu. This is where you can activate plugins.
To see this menu, you have to:
- be an administrator,
- be using the full interface.
If then the menu doesn't appear, it is probable that your /plugins
folder is not correctly installed.
On this configuration page, you will see the list of installed
plugins. You can check plugins to activate them, and uncheck them to
deactivate them.
By clicking on the small arrow next to each plugin, you will see
information about the plugin:
its version and state:
stable : the plugin has been tested and should work properly;
test : the plugin is in a testing phase. Their may still be some bugs;
experimental : the plugin is an experiment and there are no guarantees
about its stability;
dev : the plugin is still in development, you should avoid installing
the plugin on a production website.
the author(s) of the plugin;
a description;
a link to an external information page.
WARNING
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As with any software, it is advisable to look carefully at what you
install on your server. A plugin can be in a development phase and
thus might be risky to use and could damage your data. A plugin could
also be presented as stable even if it contains errors or security
holes. So you should be careful where and from whom you get your
plugins.
In case of doubt, you can always get advice on the different mailing
lists and forums of the SPIP community.
Also remember that, in some cases, two plugins could be incompatible
and produce problems when activated at the same time.
If you are using plugins and find what looks like a bug in SPIP, you
should first check that this bug can be reproduced without any plugins
activated before you report the bug to the SPIP developers.
If the bug disappears when all plugins are deactivated, you should
find which plugin is causing the problem by activating each plugin one
by one and noting the exact configuration in which it occurs. Without
this information, it will be more difficult for the community to find
a solution.