A short followup: I turned another user in the group loose to install something from CPAN, and (after I made sure all the directories under the installation base had both group write permission, and "make all files created hereunder belong to this group" permission), things went fairly well.
One install issued some warnings about chmod 666 failing for lack of permissions (which would make sense if the operation were being attempted on a file owned by me, not by the other user), but the install succeeded nevertheless. I'll turn others loose on Monday, and we'll see if things continue smoothly, or other problems arise.
in reply to Re^2: CPAN shared by multiple users
in thread CPAN shared by multiple users