When you open a file in Linux, the question arises: Which of the
available applications should be opened? Usually, this question is
deferred to xdg-open. But, how does xdg-open know which application
is the right one and how do you configure the one you want to use
instead?🤓
To get started, try opening your file like so: xdg-open your_path.
This is just to confirm what application is opened right now. To
configure a different application, first, we have to know about the
mimetype of your_path. In this example, I'm asking for the mimetype
of an image:
$ mimetype foo.jpg foo.jpg: image/jpeg
So, the mimetype is image/jpeg. Now we can ask how xdg comes up with
the responsible application:
$ XDG_UTILS_DEBUG_LEVEL=3 xdg-mime query default image/jpeg Checking /home/munen/.config/mimeapps.list Checking /home/munen/.local/share/applications/mimeapps.list imv.desktop
We are increasing the debug level with XDG_UTILS_DEBUG_LEVEL=3 to
list the responsible application, and the paths to the
config files.
Finally, we can set a new default application. Suppose you want to open
jpegs with imv in the future. You will add the responsible desktop
entry file. My distribution (Debian) usually ships with a desktop
entry file for every package. The Debian package for imv does include
a imv.desktop file. Here's how to configure imv as the default for
image/jpeg files, then:
$ xdg-mime default imv.desktop image/jpeg
This will add the following line to one of your mimeapps.list config
files (i.e. .config/mimeapps.list):
image/jpeg=imv.desktop
How to create a custom desktop entry file
If an application doesn't have a desktop entry file, or you want to
create a custom configuration for your needs, just create a new file
in ~/.local/share/applications.
Here is an example of creating a desktop entry file for Emacs, but
instead of running Emacs (which would be the default), it uses
emacsclient. I'm using this config for all kinds of mimetypes
(directories, zip files, etc).
[Desktop Entry] Version=1.0 Name=GNU Emacs (GUI) GenericName=Text Editor Comment=GNU Emacs is an extensible, customizable text editor - and more MimeType=text/english;text/plain;text/x-makefile;text/x-c++hdr;text/x-c++src;text/x-chdr;text/x-csrc;text/x-java;text/x-moc;text/x-pascal;text/x-tcl;text/x-tex;application/x-shellscript;text/x-c;text/x-c++; Exec=/usr/bin/emacsclient -c %F Icon=emacs25 Type=Application Terminal=false Categories=Utility;Development;TextEditor; StartupWMClass=Emacs Keywords=Text;Editor;
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