These scripts are all open source and used by yours truly, which means they should be up to date pretty much all the time. Supported web sites:
git clone --recursive https://github.com/l0b0/export.git
cd export
sudo make install
Normal use is documented in each of the files. If you just want to make nightly backups, you can use the install-crontab-* targets to create crontab entries. Make sure to make a crontab backup first! I have only tested the crontab targets on my own machine, and I take no responsibility for any lost data.