Creating XDG custom url scheme handler

If you develop system tools or desktop software on Linux that also have an accompanying web application, you might want to have a way for the web application to launch the tool with some parameters specified through a web based link. For example, a link with dnf://inkscape as url, might be used to launch Gnome Software, and display the description of Inkscape, so that user may choose to install it or not.

In Linux, registering a custom URL handler can be done using XDG desktop file, of which it is configured to open x-scheme-handler MimeType.

To achieve this, you can simply create a .desktop in ~/.local/share/applications/, or /usr/local/share/applications, and configure it with MimeType=x-scheme-handler/<your-custom-proto>. If nothing went wrong with the setup, you should be able to open links with the custom url protocol afterwards.

For example, if you have a script dnfurl which takes dnf://<package-name> as its first parameter and launch Gnome Software with the package name, you can create a .desktop file with this content:

[Desktop Entry]
Version=1.0
Type=Application
Name=dnfurl
Exec=dnfurl %U
Terminal=false
NoDisplay=true
MimeType=x-scheme-handler/dnf

After installing the .desktop file, do run update-desktop-database to update the related indexes/cache. If you installed the .desktop file in ~/.local/share/applications/, you will have to run update-desktop-database ~/.local/share/applications.

If you interested with the example dnfurl program above, you can check it out at this git repository: github.com/kagesenshi/dnfurl. Or if you are in Fedora, you can install it from copr by running:

dnf copr enable izhar/dnfurl
dnf install dnfurl

Have fun~.