Make backup run in background.

[a-t-0]

TO reproduce/start debugging:

src/main.sh -un # uninstall Nextcloud

src/main.sh \
  --configure-nextcloud \
  --configure-tor \
  --local-http-nextcloud-port 80 \
  --local-https-nextcloud-port 443 \
  --external-nextcloud-port 443 \
  --ssl-password somepassword \
  --verbose

Backup

To create a backup, run:

sudo ./export_data -a -b -c -d

That creates a backup file, which can be imported with (e.g.):

sudo ./import_data -a -b -c -d /home/name/git/backup0/20230523-212316

In order of priority:

• Ensure restoring=importing the Nextcloud configuration works. #37
• Parameterise mysql_password
• Support exponential backup storage, e.g. less backups longer ago. #38
• Verify the backup can be imported on a new installation with a different Nextcloud username and password.
• Verify the backup can be imported on a new installation with a different mysql database password.
• Remove unused functions from src/backup
• Include setting backup cronjob.