This isn’t a “help” question, just a general linux question some people and I were discussing at work.

Is it possible to set limits on usage (cpu, mem, etc.) for an entire group, so for example, if the memory limit is 2GB for group “A” and one user in “A” can use 1.5GB and another can use 0.5GB, or one user could use all 2GB and other users in “A” couldn’t use any, as long as all of them added up isn’t more than 2GB?

I know /etc/security/limits.conf has a group option, but my understanding is that this just sets a limit for every user in that group, so if the limit is 2GB in there, then 5 users could use up to 10GB combined.

You can use limits and disk-quotas to limit their use of the systems disk space. As far as I know, you can’t set any kind of process quota’s. Cpu and memory is divided between all running processes and as such some may go idle freeing a timeslice to another process.