Xdg-utils

xdg-utils is a commandline tool to open/set default programs for mimetypes.
It operates using the XDG Mime Applications system.

See Also mimetypes.

Documentation

XDG Base Directory	my notes
man xdg-mime	https://manpages.debian.org/buster/xdg-utils/xdg-mime.1.en.html
gitlab	https://gitlab.freedesktop.org/xdg/xdg-utils
cgit mirror	https://cgit.freedesktop.org/xdg/xdg-utils/

Usage

Open

# use default program to open URI
xdg-open [URI]  # use default application to

Query

xdg-mime query default text/plain  # query default program for mimetype
xdg-mime query default file.pdf    # query default program for file

xdg-mime query filetype photo.jpeg        # query mimetype of file

# set to show files involved in choosing application
env XDG_UTILS_DEBUG_LEVEL=10 \
  xdg-mime query default text/html

Set Default

xdg-mime default feh.desktop image/jpeg

Special Cases

xdg-open URL

2021/05/08 there is a bug in xdg-open.

Workaround -- Set the PATH-like environment variable ${BROWSER} to control xdg-open's behaviour.

If a url is provided, the scheme is extracted using sed, and x-scheme-handler/${SCHEME} is tried.
Unfortunately, within open_generic_xdg_mime(), it re-tries the obtaining the mimetype and fails.