How to check in shell which output is primary?

[Maciej Sitarz]

Hi again,
wertarbyte developer shared on github a change to xrandr to dump the
entire configuration in an easily parsable format.

https://github.com/wertarbyte/xrandr/commit/a2abe6d3989334966dcee39fb13c23ebeaeb63b5

It has not been merged into main branch, maybe including it would be a
better idea then my few lines?

Best Regards
-- 
Maciej Sitarz