shstatus is a shell script that generates statuslines for bars that support the i3bar protocol.
Download the latest release.
$ tar xf shstatus*
$ cd shstatus-VERSION
# make install
An AUR package is also available.
See man shstatus or the online manpage.
There is an example config file in this repository.
It'll be installed to /etc/shstatus/config.sh when you run make install.