I use light for managing my screen brightness in exwm, because the repo-available xbacklight fails for want of a recognizable xserver. One day my exwm just stopped finding “light” after using it for screen brightness for a year or two. When trying to re-install with the instructions on their repo, I kept getting this error:

autoreconf: running: automake --add-missing --force-missing --warnings = portability autoreconf: no config.status: cannot re-make

The solution turned out to be to skip the autogen part of the instructions and just move on:

./autogen.sh ./configure && make sudo make install

Now light is back and my backlight is happy!

As a reference, the way I’ve set my exwm to use my regular laptop screen brightness keys to manage this is as follows in my emacs conf:

(exwm-input-set-key (kbd " <XF86MonBrightnessDown> " ) (lambda () (interactive) (shell-command " light -U 5; light " ))) (exwm-input-set-key (kbd " <XF86MonBrightnessUp> " ) (lambda () (interactive) (shell-command " light -A 5; light " )))