This is a very straight-forward module that reports the current uptime of the system.
Clone the reposistory wherever you would like.
cd ~/.config/polybar
mkdir modules
ln -s <location-of-repo>/poly-uptime.sh modules/poly-uptime.shAnd then in your polybar.ini config file, add:
; modules-right = ... poly-uptime ... ; wherever you want
; ...
[module/poly-uptime]
type = custom/script
exec = ~/.config/polybar/modules/poly-uptime.sh
tail = true