abc-user member of several groups (IDs) in the container

[tapufd]

See discussion first on your discourse:
https://discourse.linuxserver.io/t/abc-user-member-of-several-groups-ids-in-the-container/2024/3

What I finally need is to have the abc-user member of several groups (IDs) in the container.
For example PGID=1001;1002;1003
The first one 1001 would be used as GID, but the others 1002 1003 would then be extra groups the abc-user is member of.
By this I can decide in detail what the user abc has rights to…
Or have an extra variable besides PGID by which I can define the extra group memberships of the abc-user.

I think the file in question that actually does the work is:
https://github.com/linuxserver/docker-baseimage-ubuntu/blob/bionic/root/etc/cont-init.d/10-adduser

I was asked to continue the discussion here...
/T

[github-actions]

Thanks for opening your first issue here! Be sure to follow the issue template!

[tapufd]

linuxserver/docker-baseimage-alpine#56
Solution works great.