I have a group that all users on the system share. The group name is common and it is to allow for a universal fileshare for everyone on the machine. How would I make it so that all new users are added to this group by default? [No manual intervention needed on an adduser command]
/etc/adduser.conf. From the manpage:
ADD_EXTRA_GROUPS Setting this to something other than 0 (the default) will cause adduser to add newly created non-system users to the list of groups defined by EXTRA_GROUPS (below). EXTRA_GROUPS This is the list of groups that new non-system users will be added to. By default, this list is 'dialout cdrom floppy audio video plugdev users games'