Datasheet

directory, which stands for Must - Use, is not auto - created by WordPress, so it must be manually
created to be used.
The primary difference between the two is the
mu - plugins directory is for plugins that are always
executed. This means any plugin included in this directory will automatically be loaded in WordPress
and across all sites in the network if you run Multi - site.
The mu - plugins directory will not read plugins in a subfolder, so all plugins much
be individual fi les or must include additional fi les that exist in a subdirectory. Any
plugin fi les in a subfolder will be ignored unless included in the primary plugin fi le.
Types of Plugins
WordPress features a few different types and statuses
for plugins, as shown in Figure 1 - 4. You need to
understand the difference when administering and
creating plugins for WordPress.
Active — Plugin is active and running in WordPress.
Inactive — Plugin is installed but not active. No code from the plugin is executed.
Must - Use — All plugins installed in the
wp - content/mu - plugins directory. All Must - Use,
or MU, plugins are loaded automatically. The only way to deactivate an MU plugin is to
remove it completely from the directory.
Drop - ins — Core functionality of WordPress can be replaced by Drop - in plugins. These
plugins are a specifi cally named PHP fi les located in the
wp - content directory. If WordPress
detects one of these fi les, it will be auto - loaded and listed under the Drop - in fi lter on the
Plugin screen. Currently ten Drop - in plugins are available:
advanced - cache.php — Advanced caching plugin
db.php — Custom database class
db - error.php — Custom database error message
install.php — Custom installation script
maintenance.php — Custom maintenance message
object - cache.php — External object cache
sunrise.php — Advanced domain mapping
blog - deleted.php — Custom blog deleted message
blog - inactive.php — Custom blog inactive message
blog - suspended.php — Custom blog suspended message
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FIGURE 1 - 4
Installing and Managing Plugins
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