Instead of hardcoding db credentials in mainsite_backup.sh, load from wp-config.php. Make scripts agnostic to directory they are called from. Pull directory of wordpress into config file. Some robustness improvments.
Make git upgrade script directory independent. Pull out more settings into shared_config file and make that a sample config, ignore the real one.
Rename mainsite_backup.sh -> wp_db_backup.sh
Write readme w/ setup & usage instructions.