backup.sh

I think I got the base of this backup script from https://blog.bithive.space/post/automatic-backups-with-restic/ (but I'm not 100% sure) This is my extension of that script which serves my purposes. I have added a notification wrapper, some error checking (which still could be improved) and moved a lot of stuff to the env file so that the base script can be run without local changes getting overwitten

Running it

Eventually I will probably formalize this documentation a bit better, but the quick version is:

1. mkdir /etc/restic
2. copy the backup.sh to /etc/restic
3. copy the env to /etc/restic
4. modify the env to suit your needs
5. setup the systemd timer stuff
   1. copy the etc/systemd/system/restic-backup.* files to /etc/systemd/system
   2. systemctl daemon-reload
   3. systemctl enable --now restic-backup.timer