X Desktop Group David Faure

faure@kde.org

2 April 2014 1.0 The freedesktop.org Shared MIME database provides a single way to store static information about MIME types and rules for determining a type. The freedesktop.org Desktop Entry specification allows applications to announce which MIME types they support. This specification solves the remaining issues: which application should open a file by default, how to let the user change the default application, and how to let the user add or remove associations between applications and mimetypes. Users, system administrators, application vendors et distributions can change associations between applications and mimetypes by writing into a file called mimeapps.list. The lookup order for this file is as follows: $XDG_CONFIG_HOME/$xdc-mimeapps.listuser overrides, desktop-specific (for advanced users) $XDG_CONFIG_HOME/mimeapps.listuser overrides (recommended location for user configuration GUIs) $XDG_CONFIG_DIRS/$xdc-mimeapps.listsysadmin and ISV overrides, desktop-specific $XDG_CONFIG_DIRS/mimeapps.listsysadmin and ISV overrides $XDG_DATA_HOME/applications/$xdc-mimeapps.listfor completeness, deprecated, desktop-specific $XDG_DATA_HOME/applications/mimeapps.listfor compatibility, deprecated $XDG_DATA_DIRS/applications/$xdc-mimeapps.listdistribution-provided defaults, desktop-specific $XDG_DATA_DIRS/applications/mimeapps.listdistribution-provided defaults In this table, $xdc means the lowercase version of $XDG_CURRENT_DESKTOP (for instance, kde, gnome, xfce, etc.) All of the above files are referred to as "mimeapps.list" in the rest of this specification, for simplicity. Indicating the default application for a given mimetype is done by writing into the group [Default Applications] in the file mimeapps.list. The [Default Applications] group indicates the preferred application for a given mimetype. This is for instance the one that will be started when left-clicking on a file in a file manager. If the application is no longer installed, the next application in the list is used. This example ensures that the application default1.desktop will be used for mimetype1, if it's installed, and otherwise default2.desktop if it's installed: [Default Applications] mimetype1=default1.desktop;default2.desktop In the absence of such an entry, the next mimeapps.list is checked. Once all levels have been checked, if no entry could be found, the implementations can pick any of the .desktop files associated with the mimetype, taking into account added and removed associations as per the next section. Adding and removing associations between mimetypes and applications is done with the following syntax in the mimeapps.list file: [Added Associations] mimetype1=foo1.desktop;foo2.desktop;foo3.desktop mimetype2=foo4.desktop [Removed Associations] mimetype1=foo5.desktop The [Added Associations] group defines additional associations of applications with mimetypes, as if the .desktop file was listing this mimetype in the first place. The entries in [Default Applications] should also be considered to add an association between application and mimetype in the same manner. The [Removed Associations] group removes associations of applications with mimetypes, as if the .desktop file was NOT listing this mimetype in the first place. The suggested algorithm for listing the applications associated to a given mimetype is: add any "Default Applications" and then "Added Associations" in the first mimeapps.list make a blacklist with the "Removed Associations" in the first mimeapps.list add any "Default Applications" and then the "Added Associations" in the second mimeapps.list, except those in the current blacklist append to the blacklist the "Removed Associations" in the second mimeapps.list repeat the last two steps for all subsequent mimeapps.list files finish by adding the mimetypes listed in the .desktop file, except those in the blacklist