Date: Wed, 19 Mar 1997 21:53:19 -0700 From: Warner Losh <imp@village.org> To: "Jordan K. Hubbard" <jkh@time.cdrom.com> Cc: Mike Pritchard <mpp@freefall.freebsd.org>, hackers@freebsd.org Subject: Re: dup3() - I've thought it over and decided... Message-ID: <E0w7Zqq-0001Ye-00@rover.village.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>
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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).
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