Manual:$wgUploadPath

Details
The absolute URL of the upload directory. This is used to construct URL for viewing uploaded files.

In most cases this is just the path component, such as "/w/images". If uploaded files are served from a different domain, this can be a fully-qualified URL with hostname, such as "http://upload.wikimedia.org/wikipedia/en".

Note: $wgEnableUploads is commented out by default. Also remember to set directory permissions.

To enable permission checks on image files, $wgUploadPath can be pointed to the img_auth.php script ( $wgUploadPath = $wgScriptPath."/img_auth.php"; ) - see Manual:Image Authorisation for instructions.


 * There are other variables which are defined relative to this one. If you redefine this in your LocalSettings.php then all dependent variables including wgUploadDirectory will need redefining also. If both these settings are not coherent the files will be uploaded to different folder  than from where MediaWiki will try to retrieve it for viewing !