Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!think!barmar From: barmar@think.COM (Barry Margolin) Newsgroups: comp.unix.questions Subject: Re: Is UNIX(TM) Multi-User? Message-ID: <26205@think.UUCP> Date: 23 Aug 88 05:48:15 GMT References: <880@taux01.UUCP> <213@bhjat.UUCP> <1640@uop.edu> <404@cpro.UUCP> <15287@shemp.CS <365@pigs.UUCP> <11945@steinmetz.ge.com> Sender: usenet@think.UUCP Reply-To: barmar@kulla.think.com.UUCP (Barry Margolin) Organization: Thinking Machines Corporation, Cambridge, MA Lines: 24 In article <11945@steinmetz.ge.com> davidsen@crdos1.UUCP (bill davidsen) writes: > Any multitasking o/s can be a multiuser system, provided that the user >agent (shell or whatever) is a normal process. Given this, you can have >multiple user agents running, connected to several users. If "multiuser" means that more than one person can use the system simultaneously, that is true, but I don't think this is a reasonable definition of multiuser. For example, Symbolics Lisp Machines run a multitasking O/S, and you can have multiple user agents (one on the bitmapped console, others on Telnet clients, X servers, or serial terminals) , but all the processes share a single address space. In particular, the userid and the file server connections are global variables, so all the processes are considered to be owned by the same user. So, multiple people can be using the system, but only one "user" is ever logged in. There are other pieces of global state that might not cause trouble, but would probably cause confusion among multiple users. Barry Margolin Thinking Machines Corp. barmar@think.com {uunet,harvard}!think!barmar