Desktop entries is a freedesktop.org standard for specifying the behaviour of programs running on X Window Systems. It is a configuration file that describe how an application is launched and how it appears in a menu with an icon. The most common desktop entries are the
.directory files. This article explains briefly how to create useful and standard compliant desktop entries. It is mainly intended for package contributors and maintainers, but may also be useful for software developers and others.
There are roughly three types of desktop entries:
- a shortcut to an application
- a shortcut to a web link.
- a container of meta data of a menu entry
The following sections will roughly explain how these are created and validated.
Desktop entries for applications or
.desktop files are generally a combination of meta information resources and a shortcut of an application. These files usually reside in
/usr/share/applications for systemwide installed applications or
~/.local/share/applications for user specific applications.
Following is an example of its structure with additional comments. The example is only meant to give a quick impression, and does not show how to utilize all possible entry keys. The complete list of keys can be found in the freedesktop.org specification.
[Desktop Entry] Type=Application # Indicates the type as listed above Version=1.0 # The version of the desktop entry specification to which this file complies Name=jMemorize # The name of the application Comment=Flash card based learning tool # A comment which can/will be used as a tooltip Exec=jmemorize # The executable of the application. Icon=jmemorize # The name of the icon that will be used to display this entry Terminal=false # Describes whether this application needs to be run in a terminal or not Categories=Education;Languages;Java; # Describes the categories in which this entry should be shown
All Desktop recognized desktop entries can be found on the site of the project Freedesktop.org site on the following link.
For example the
Type key defines 3 types of desktop entries: Application (type 1), Link (type 2) and Directory (type 3).
Versionkey does not stand for the version of the application, but for the version of the desktop entry specification to which this file complies.
Commentoften contain redundant values in the form of combinations of them, like:
Name=Pidgin Internet Messenger GenericName=Internet Messenger
Name=NoteCase notes manager Comment=Notes Manager
This should be avoided, as it will only be confusing to users. The
Name key should only contain the name, or maybe an abbreviation/acronym if available.
GenericNameshould state what you would generally call an application that does what this specific application offers (i.e. Firefox is a "Web Browser").
Commentis intended to contain any usefull additional information.
There are quite some keys that have become deprecated over time as the standard has matured. The best/simplest way is to use the tool
desktop-file-validate which is part of the package . To validate, run
$ desktop-file-validate <your desktop file>
This will give you very verbose and useful warnings and error messages.
Common image formats
Here is a short overview of image formats commonly used for icons.
|Extension||Full Name and/or Description||Graphics Type||Container Format||Supported|
|.png||Portable Network Graphics||Raster||no||yes|
|.svg(z)||Scalable Vector Graphics||Vector||no||yes (optional)|
|.xpm||X PixMap||Raster||no||yes (deprecated)|
|.gif||Graphics Interchange Format||Raster||no||no|
|.ico||MS Windows Icon Format||Raster||yes||no|
|.icns||Apple Icon Image||Raster||yes||no|
If you stumble across an icon which is in a format that is not supported by the freedesktop.org standard (like gif or ico), you can convert (which is part of the imagemagick package) it to a supported/recommended format, e.g.:
$ convert <icon name>.gif <icon name>.png /* Converts from gif to png */
If you convert from a container format like ico, you will get all images that were encapsulated in the ico file in the form <icon name>-<number>.png. If you want to know the size of the image, or the number of images in a container file like ico you can use identify (also part of the imagemagick package)
$ identify /usr/share/vlc/vlc48x48.ico /usr/share/vlc/vlc48x48.ico ICO 32x32 32x32+0+0 8-bit DirectClass 84.3kb /usr/share/vlc/vlc48x48.ico ICO 16x16 16x16+0+0 8-bit DirectClass 84.3kb /usr/share/vlc/vlc48x48.ico ICO 128x128 128x128+0+0 8-bit DirectClass 84.3kb /usr/share/vlc/vlc48x48.ico ICO 48x48 48x48+0+0 8-bit DirectClass 84.3kb /usr/share/vlc/vlc48x48.ico ICO 32x32 32x32+0+0 8-bit DirectClass 84.3kb /usr/share/vlc/vlc48x48.ico ICO 16x16 16x16+0+0 8-bit DirectClass 84.3kb
As you can see, the example ico file, although its name might suggest a single image of size 48x48, contains no less than 6 different sizes, of which one is even greater than 48x48, namely 128x128. And to give a bit of motivation on this subject, at the point of writing this section (2008-10-27), the 128x128 size was missing in the vlc package (0.9.4-2). So the next step would be to look at the vlc PKGBUILD and check whether this icon format was not in the source package to begin with (in that case we would inform the vlc developers), or whether this icon was somehow omitted from the Arch-specific package (in that case we can file a bug report at the Arch Linux bug tracker). (Update: this bug has now been fixed, so as you can see, your work will not be in vain.)
Although packages that already ship with a .desktop-file most certainly contain an icon or a set of icons, there is sometimes the case when a developer has not created a .desktop-file, but may ship icons, nonetheless. So a good start is to look for icons in the source package. You can i.e. first filter for the extension with find and then use grep to filter further for certain buzzwords like the package name, "icon", "logo", etc, if there are quite a lot of images in the source package.
$ find /path/to/source/package -regex ".*\.\(svg\|png\|xpm\|gif\|ico\)$" /* this filters for common extensions */
If the developers of an application do not include icons in their source packages, the next step would be to search on their web sites. Some projects, like i.e. tvbrowser have an artwork/logo page where additional icons may be found. If a project is multi-platform, there may be the case that even if the linux/unix package does not come with an icon, the Windows package might provide one. If the project uses a Version control system like CVS/SVN/etc. and you have some experience with it, you also might consider browsing it for icons. If everything fails, the project might simple have no icon/logo yet.
started as an Arch Linux-specific tool for generating .desktop files by fetching the needed information directly from PKGBUILD files. Now it is a general tool that takes command-line arguments.
Icons can be automatically downloaded from openiconlibrary, if available. (The source for icons can easily be changed in the future).
How to use
- Start the
gendesk --pkgname "$pkgname" --pkgdesc "$pkgdesc"
- Alternatively, if an icon is already provided ($pkgname.png, for instance). The
-nflag is for not downloading an icon or using the default icon. Example:
gendesk -n --pkgname "$pkgname" --pkgdesc "$pkgdesc"
$srcdir/$pkgname.desktopwill be created and can be installed in the
install -Dm644 "$pkgname.desktop" "$pkgname/usr/share/applications/$pkgname.desktop"
- The icon can be installed with:
install -Dm644 "$pkgname.png" "$pkgname/usr/share/pixmaps/$pkgname.png"
--name='Program Name'for choosing a name for the menu entry.
--exec='/opt/some_app/elf --with-ponies'for setting the exec field.
- See the gendesk project for more information. (Patches and pull requests are welcome).