Special files
YOURLS support a number of special user files to further customize some internal behaviors.
They are all loaded from the user/ folder.
Pages
Pages are custom files in user/pages/ that will be displayed when requested like short URLs.
See Pages for details.
Custom DB error page
If the database becomes unreachable, or YOURLS is misconfigured, a default YOURLS error page is displayed.
You can replace this error page with a custom user/db_error.php
Custom maintenance page
When you update YOURLS to a new version (good job!) the site may become briefly inaccessible and a default landing page is displayed.
You can replace this page with a custom version located at user/maintenance.php
Custom favicon
By default YOURLS displays a tiny YOURLS favicon.
You can easily display a custom favicon with your own user/favicon.(jpg|gif|png|ico|svg).
Custom "always-on plugin"
If present, YOURLS will always include user/cache.php early during the boot process, before regular active plugins are loaded.
This special file will not appear in the list of plugins and cannot be activated or deactivated in the admin area. To deactivate it, delete (or rename) it manually.
"Cache" stands for "Custom Additional Code for Hazardous Extensions".
Custom DB layer
Out of the box, YOURLS uses PDO to interact with a MySQL server.
If you are an experienced coder and want to replace the core DB engine, you can implement your own library in user/db.php.