A script to change lightdm-slick-greeter's theme with pywal.
Currently, the slickgreeter-pywal install script will generate a wallpapers directory in /usr/share with full read and write permissions, and it will generate/edit /etc/lightdm/slick-greeter.conf so that there is a [Greeter] section and the line background=/usr/share/wallpapers/wal within the greeter section. The reTheme script just calls wal -i <path-to-image> and copies the image to the file /usr/share/wallpapers/wal.
Once the install script has been run, simply use the command reTheme <path-to-image> inplace of wal -i <path-to-image>.
sudo chmod 777 install.sh
sudo ./install.sh
reTheme (cat $HOME/.cache/wal/wal)
and in the future, instead of running wal -i <path-to-image>, you should run reTheme <path-to-image>.