Private preg_replace callback used in image_add_caption().

Copy an existing image file.

Registers the internal custom header and background routines.

Test if the current device has the capability to upload files.

Retrieve IDs that are not already present in the cache.

Gets random header image data from registered images in theme.

Retrieve the path or URL of an attachment’s attached file.

Adds any posts from the given IDs to the cache that do not already exist in cache.

Removes arguments from a query string if they are not present in a URL DO NOT use this in plugin code.

Kills WordPress execution and displays an error message.