How do I change default associations for URI schemas?

Help
1

In Windows, ms-settings:defaultapps allows you to change the default associations for URI schemas (like vscode:) in addition to file extensions.

In contrast, kcmshell6 kcm_filetypes solely appears to be capable of setting them for (custom) IANA Media Type-representations of file extensions.

Consequently, how can these be configured (outside of the web browser, considering that they can be invoked elsewhere)?

2

There are essentially two levels to that.

When applications get installed they usually also install a so called “desktop file”.
Global location for distribution packages is /usr/share/applications on most distributions, user local default location is $HOME/.local/share/applications

Each application can list its URI scheme capabilities in its .desktop file, for example the steam.desktop file on my system has a line like this
MimeType=x-scheme-handler/steam;x-scheme-handler/steamlink;

and the signal-desktop.desktop file has a line like this
MimeType=x-scheme-handler/sgnl;x-scheme-handler/signalcaptcha;

As long as there is only one application for a given scheme that application is obviously also the default.

Now, if multiple applications have support for a scheme, the mimeapps.list file is consulted.
Its system default location is /etc/xdg/mimeapps.list and its user local default location is $HOME/.config/mimeapps.list

It can have a section called [Default Applications} with entries like
x-scheme-handler/sgnl=signal-desktop.desktop
making signal-desktop.desktop the default for sgnl:// URIs.

On a tool level you can make use of xdg-mime to query and set such associations

“Tell me which application handles sgnl:// URIs”
xdg-mime query default x-scheme-handler/sgnl

“I want Signal to handle sgnl:// URIs”
xdg-mime default signal-desktop.desktop x-scheme-handler/sgnl

2 Likes
3

@krake, thanks. Lots. I presume this functionality isn’t exposed via systemsettings too?

4

@rokejulianlockhart I am happy this was helpful :slight_smile:

I didn’t find anything for this in System Settings myself either but I might not have all modules installed.

If not I would guess that could be added relatively easily.
Maybe add an entry in the Brainstorm section?

1 Like
5

Right; the Default Applications page in System Settings shows a hardcoded set of URI handlers, not all of them that are available on the system.

1 Like
6

One additional question for verification… will the .desktop MimeType on ~.local/share/applications supercede those from /usr/share/applications?

1 Like
7

That’s correct.

1 Like
8

This is simplified version of how I set qbittorrent as magnet handler.

$ rpm -ql qbittorrent | grep desktop
/usr/share/applications/org.qbittorrent.qBittorrent.desktop
$ 
$ xdg-mime default org.qbittorrent.qBittorrent.desktop x-scheme-handler/magnet
$ 
$ xdg-mime query default x-scheme-handler/magnet
org.qbittorrent.qBittorrent.desktop
$
1 Like
9 
$ cat ~/.config/mimeapps.list | grep magnet
x-scheme-handler/magnet=org.qbittorrent.qBittorrent.desktop;
x-scheme-handler/magnet=org.qbittorrent.qBittorrent.desktop

First one in [Added Association]. Second one in [Default Application]

1 Like