Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!henry From: henry@utzoo.UUCP (Henry Spencer) Newsgroups: net.unix-wizards,net.dcom Subject: Re: any harm in allowing only ctrl-Q to restart output? Message-ID: <4854@utzoo.UUCP> Date: Wed, 2-Jan-85 12:57:38 EST Article-I.D.: utzoo.4854 Posted: Wed Jan 2 12:57:38 1985 Date-Received: Wed, 2-Jan-85 12:57:38 EST References: <247@lsuc.UUCP> Organization: U of Toronto Zoology Lines: 23 Strictly speaking, ctrl-Q should be the only thing that restarts output. The fundamental problem is that flow-control protocols really ought to be implemented so that they are invisible to higher levels, notably to the user, and XON/XOFF isn't. So we have a fundamental confusion about whether the terminal is invoking flow control to slow down (not stop) the flow of data, or whether the user is invoking the same machinery to stop output for some potentially-unbounded period. The decision about restart characters depends on which of these cases is occurring. If the user is stopping output, restarting it on any input character is a much more "idiot-proof" approach. Ctrl-Q is not exactly an obvious combination for a user who is wondering why in $^%$^% his terminal won't respond. It's not too bad if he stopped output deliberately, but if he hit ctrl-S quite by accident...! On the other hand, if the terminal knows about the flow- control protocol and is using it deliberately, then violations of it are fraught with potential problems, as you're discovering. There is no entirely satisfactory solution. Given that the violation of the protocol is fouling up the terminals, your best solution is probably to make the change and live with the occasional "my terminal is hung" phone calls that will result. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry