From owner-freebsd-hackers Wed Mar 19 20:53:51 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id UAA25255 for hackers-outgoing; Wed, 19 Mar 1997 20:53:51 -0800 (PST) Received: from rover.village.org (rover.village.org [204.144.255.49]) by freefall.freebsd.org (8.8.5/8.8.5) with SMTP id UAA25250 for ; Wed, 19 Mar 1997 20:53:47 -0800 (PST) Received: from rover.village.org [127.0.0.1] by rover.village.org with esmtp (Exim 0.56 #1) id E0w7Zqq-0001Ye-00; Wed, 19 Mar 1997 21:53:20 -0700 To: "Jordan K. Hubbard" Subject: Re: dup3() - I've thought it over and decided... Cc: Mike Pritchard , hackers@freebsd.org In-reply-to: Your message of "Wed, 19 Mar 1997 01:06:03 PST." <20682.858762363@time.cdrom.com> References: <20682.858762363@time.cdrom.com> Date: Wed, 19 Mar 1997 21:53:19 -0700 From: Warner Losh Message-Id: Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk In message <20682.858762363@time.cdrom.com> "Jordan K. Hubbard" writes: : Anyone remember a timesharing system called ITS (from MIT)? If you : got disconnected from the modem (not uncommon in those days of : Pennywhistle, 300 baud acoustically-coupled modems :-) you wouldn't : lose your session, like you do under UNIX, rather the next time you : logged in it would ask you: : : [Attach your detached tree?] : : And if you said 'y' you'd get your old process tree back, everything : right where you left it. VMS kinda did this too. Its terminal driver was "detachable" and you could then "attach" a new tty. Basically, you had an upper level interface (the virtual TTY) and a lower interface (the physical hardware). An instance of a tty could talk to any physical device[*]. Maybe something like that would be a useful abstraction. I actually think that you can likely do the terminal redirection in a souped up pty driver. I think that doing one per command is insanely expensive, but some abstraction like VMS might help, since the detach did the right thing wrt buffered I/O and the like. Warner [*] well, to the bottom half of the driver, so things like DECnet terminals and TCP/IP Telnet session stuck around when the net flaked out. Very handy back when I was at the slow end of the net (a 9600 baud link to sri-nic on the arapa net).