So I've done some Google searching and this is something that has very little knowledge out there. What would be an effective and foolproof way of detecting whether X11 or Wayland is in use, preferrably at compile-time and with CMake? I need to apply this to a C++ project of mine.
2 Answers
The accepted answer is very inaccurate and dangerous. It just runs loginctl to dump a large list of user-sessions and greps every line with a username or other string that matches the current user's name, which can lead to false positives and multiple matching lines. Calling whoami is also wasteful. So it's harmful, and inaccurate.
Here's a much better way to get the user's session details, by querying your exact username's details and grabbing their 1st session scope's id.
This is a Bash/ZSH-compatible one-liner solution:
if [ "$(loginctl show-session $(loginctl user-status $USER | grep -E -m 1 'session-[0-9]+\.scope' | sed -E 's/^.*?session-([0-9]+)\.scope.*$/\1/') -p Type | grep -ic "wayland")" -ge 1 ]; then
echo "Wayland!"
else
echo "X11"
fi
I really wish that loginctl had a "list all sessions just for a specific user", but it doesn't, so we have to resort to these tricks. At least my trick is a LOT more robust and should always work!
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