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: