From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnold@skeeve.com (arnold@skeeve.com) Date: Thu, 28 Jul 2016 21:05:05 -0600 Subject: [TUHS] environments/universes (was: Unix v6 problem with /tmp) In-Reply-To: <20160728231639.GA299581@lisa.in-ulm.de> References: <57991A21.5030404@gmail.com> <20160728231639.GA299581@lisa.in-ulm.de> Message-ID: <201607290305.u6T355aq009962@freefriends.org> Sven Mascheck wrote: > Sequent Dynix "universes" (idea picked up by Siemens Sinix) puts several > targets in one symlink. Example: > > ln -c ucb=.bin att=/usr/att/bin /bin > > and the actual resolving (and usage of different default PATHs) > is controlled by an environment variable, as far as I know > (s.a. http://www.in-ulm.de/~mascheck/various/universes/) Pyramid did something similar, also called universes, in the mid-80s. I think they used a system call and corresponding command to set the visible universe either to BSD or System V. I don't remember the details as to how exactly it worked. I *think* this was before Dynix, but I'm not sure. We had a Pyramid when I was working at Georgia Tech. DMR visited one time and spoke; I remember him saying that he thought what Pyramid had done was an awful idea... :-) (They were interesting machines. It was RISC, with loadable microcode... About the same speed as a Vax 780 but half the price.) Arnold