Possible to adjust default exclude.list

[LubosRemplik]

I think there is need to be possible to adjust default exclude.list which is generated by application since, as described in several issues, the rsync takes list from top to bottom and we are not able to "include" some excluded folders again, e.g. /var/lib/docker/volumes

The best imo would be to have exclude.list in /etc/timeshift folder, but the config in timeshift.json as per below PR is OK too

Related

• A way to include certain docker data volumes in /var/lib/docker/volumes? #863
• Default exclusions externalised to json config file #796
• maybe more