The upload.php script is automatically included from stdconfig.php if the $EnableUpload variable is true in config.php. Note that one may still need to set an upload password before users can upload (see Uploads Admin).
The directory where uploads are to be stored. Defaults to uploads/ in the pmwiki directory, but can be set to any location on the server. This directory must be writable by the webserver process if uploading is to occur.
Sets the prefix for uploaded files to allow attachments to be organized other than by groups. Defaults to '/$Group' (uploads are organized per-group), but can be set to other values for sitewide or per-page attachments.
When set to 1 (the default), links to attachments bypass Pm Wiki and come directly from the webserver. Setting $EnableDirectDownload=0; causes requests for attachments to be obtained via ?action=download. This allows Pm Wiki to protect attachments using a page's read permissions, but also increases the load on the server.
When set to 1 (default is 0), uploading a file to a location where a file of the same name already exists causes the old version to be renamed to file.ext,timestamp (instead of being overwritten). timestamp is a Unix-style timestamp.