Registering Applications for MIME Types

Applications are registered by creating a MimeType key in the .desktop entry file and listing each MIME type separated by a semicolon. The MimeType key should only be used in the .desktop files whose Type key has Application as value. For more information about .desktop files, see How to Add or Modify MIME Types.

How to Register Applications for MIME Types

1. Create a .desktop file for the application in the $XDG_DATA_HOME/applications or $XDG_DATA_DIRS/applications directory.

   The .desktop file must include a MimeType key whose value comprises each MIME type to be registered, separated by semicolons. For example: MimeType=text/html;text/css;text/x-javascript

   ---

   Note - The MimeType key should only be used in the .desktop files whose Type key has Application as the value. For more information about .desktop files, see Working With Desktop Entry Files.

   ---

2. Update the application database.

   # update-desktop-database

   This command creates or updates the mimeinfo.cache file in the same directory as the .desktop file. This cache file is used to facilitate MIME type searches.

3. Create or update the defaults.list file in the same directory as the .desktop file.

   The defaults.list file is a plain text file that specifies the default application to use for specific MIME types. Each line in the file consists of the MIME type, the = symbol and the Desktop File ID, which is the filename for the desktop entry file. For more information, see Example 6-3.

   ---

   Note - Registering MIME types for applications is part of the XDG desktop entry specification rather than the shared mime info specification. For more information, see http://www.freedesktop.org/wiki/Standards/desktop-entry-spec.

   ---

Example 6-3 A User's defaults.list File

[Default Applications]
application/pdf=evince.desktop
text/html=epiphany.desktop
text/plain=gedit.desktop
image/jpeg=eog.desktop
image/png=eog.desktop
text/xml=gedit.desktop

How to Associate a MIME Type With an Application

1. Add a menu item for the application.

   For more information about how to add an item to a menu, see How to Add a Menu.

2. Add an icon for the application to the /usr/share/icons/theme-name/icon-size/apps directory.

   For more information about installing icons and themes, see Installing Icons for Themes.

3. If the application uses a new MIME type, perform the following steps:
   1. Add a source XML file to the MIME database.

      For more information, see Modifying MIME Types.

   2. Add an icon for the MIME type to /usr/share/icons/theme-name/icon-size/mimetypes.

      For more information on icons and themes, see Chapter 4, Installing Themes.

4. To associate the application with a MIME type, include a MimeType key in your .desktop file.

   For more information, see Registering Applications for MIME Types.