See also: Uploads, Uploads admin.

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 UploadsAdmin).
An array containing as keys the file extensions that can be attached to the wiki, and as values the standard MIME content types of these extensions. See Adding new file types to permitted uploads.
By default, PmWiki only checks file extensions, and users could upload files with wrong extensions (say, a PDF file with a DOC extension, or a file with a disallowed extension renamed to an allowed one). Setting this variable to true will check the MIME content type of the uploaded file, and if it doesn't match the one defined in $UploadExts, the upload will be refused.
$EnableUploadMimeMatch = true;
Note that occasionally this may block valid files, for example a CSV file may be detected as "text/plain" or "application/csv", or a password-protected office file may appear as "application/encrypted". To allow such files, configure the allowed content-types for the extension as regular expressions:
 $EnableUploadMimeMatch = array(
This array contains forbidden strings for an uploaded file (case insensitive). Some installations with the Apache server will try to execute a file which name contains ".php", ".pl" or ".cgi" even if it is not the last part of the filename. For example, a file named "test.php.txt" may be executed. To disallow such files to be uploaded, add to config.php such a line:
$UploadBlacklist = array('.php', '.pl', '.cgi', '.py'); # disallow common script files
This variable sets additional unix permissions applied to newly uploaded files, and should be 0 (recommended as of 2013). If uploaded files cannot be downloaded and displayed on the website, for example with the error 403 Forbidden, set this value to 0444 (core setting, default since 2004).
$UploadPermAdd = 0; # recommended
This variable sets unix permissions unconditionally applied to newly uploaded files, for example 0604. Danger! Do not use this variable unless you know what you're doing! If you make a mistake, uploaded files may be impossible to edit or delete via the FTP/SSH account (in that case, Cookbook:Attachtable may be used) or to be downloaded and displayed on the website. Note that file permissions may differ on different systems - if you copy or move your PmWiki installation, you may have to change it.
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.
The url of the directory given by $UploadDir. By default, $UploadUrlFmt is derived from $PubDirUrl and $UploadDir.

The format of the upload link displayed when an attachment exists. Can be changed with such a line in config.php:
$IMapLinkFmt['Attach:'] = "<a class='attachlink' href='\$LinkUrl'>\$LinkText</a>";
The format of the upload link displayed when an attachment not present. Can be changed with such a line in config.php:
$LinkUploadCreateFmt = "<a class='createlinktext' href='\$LinkUpload'>\$LinkText</a>
<a class='createlink' href='\$LinkUpload'>&nbsp;&Delta;</a>";
Sets the prefix for uploaded files to allow attachments to be organized other than by groups. Defaults to '/$Group' (uploads are organized per-group), but can be set to other values for sitewide or per-page attachments.
$UploadPrefixFmt = '/$Group/$Name'; # per-page attachments
$UploadPrefixFmt = ''; # sitewide attachments
It is recommended to have the $UploadPrefixFmt variable defined in config.php, the same for all pages in the wiki, and not in group/page local configuration files. Otherwise you will be unable to link to attachments in other wikigroups.
When set to 1 (the default), links to attachments bypass PmWiki and come directly from the webserver. Setting $EnableDirectDownload=0; causes requests for attachments to be obtained via ?action=download. This allows PmWiki to protect attachments using a page's read permissions, but also increases the load on the server. Don't forget to protect your directory /uploads/ with a .htaccess file (Order Deny,Allow / Deny from all).
When the wiki has protected downloads (see $EnableDirectDownload), it sends a HTTP header "Accept-Ranges" and can serve partial content if the browser requests it. This can be useful for large files such as videos, and is enabled by default. Set this variable to 0 to disable this feature and serve whole files only.
Set $EnableUploadGroupAuth = 1; to authenticate downloads with the group password. This could be used together with $EnableDirectDownload = 0;. Note: $EnableUploadGroupAuth should not be enabled if your wiki uses per-page attachments.
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.
When set to 1 (the default), determines if overwriting previously uploaded files is allowed.
The set of characters allowed in upload names. Defaults to "-\w. ", which means alphanumerics, hyphens, underscores, dots, and spaces can be used in upload names, and everything else will be stripped. It is only possible to enable characters that exist in the code page (charater set) of the wiki, see Wikipedia:Code page.
$UploadNameChars = "-\\w."; # default: allow dash, letters, digits, underscore, and dots (no spaces)
$UploadNameChars = "-\\w. \\x80-\\xff"; # allow Unicode
Note: Not all characters can be used in file names, because of various limitations in protocols or operating systems, file systems and server software, or conflict with PmWiki markup:
  • +?:@#%!=/ have special meanings in URL addresses,
  • |\^`[]?:@#%/ may be impossible to save on some systems,
  • <>"|\^`(){}[]#% may conflict with PmWiki markups,
so it is strongly recommended to only enable those if you know what you're doing.
An array of regular expression replacements that is used to normalize the filename of an attached file. First, everything but $UploadNameChars will be stripped, then the file extension will be converted to lowercase. Administrators can override these replacements with a custom definition (the full array needs to be defined). Currently the default sequence is:
    $MakeUploadNamePatterns = array(
    "/[^$UploadNameChars]/" => '', # strip all not-allowed characters
    '/\\.[^.]*$/' => 'cb_tolower', # convert extension to lowercase (callback function)
    '/^[^[:alnum:]_]+/' => '',     # strip initial spaces, dashes, dots
    '/[^[:alnum:]_]+$/' => ''))    # strip trailing spaces, dashes, dots
Overall size limit for all uploads.
   $UploadDirQuota = 100*1024;         # limit uploads to 100KiB
   $UploadDirQuota = 1000*1024;        # limit uploads to 1000KiB
   $UploadDirQuota = 1024*1024;        # limit uploads to 1MiB
   $UploadDirQuota = 25*1024*1024;     # limit uploads to 25MiB
   $UploadDirQuota = 2*1024*1024*1024; # limit uploads to 2GiB
Overall size limit for one directory containing uploads. This directory is usually uploads/GroupName (one for every WikiGroup), or uploads/Group/PageName (one for every page), depending on the variable $UploadPrefixFmt.
Maximum size for uploading files, 50000 octets (bytes) by default.
Maximum size per extension, overriding the default in $UploadMaxSize.
   $UploadExtSize['zip'] = 2*1024*1024; # allow up to 2MiB for zip files
The function to be called after a file was posted. By default the "Redirect" function is called with arguments $pagename and the URL of the ?action=upload page (with additional information if the upload was successful or why it wasn't, and if the file was renamed). An add-on may define its own function, for example an AJAX upload may only return some variable back to the browser.

This page may have a more recent version on pmwiki.org: PmWiki:UploadVariables, and a talk page: PmWiki:UploadVariables-Talk.