barry@giaea.gi.oz (Computer Centre Manager) (09/19/90)
We have an HP 9000/825 using HPUX 7.0. We want to turn off the computer echo via "stty -echo" to save X.25 transmission costs. In both sh and csh we can't, but it works fine in ksh. We have processes that explicitly turn off echo, that work fine, but as soon as you are back in sh or csh, echo is put back on. Any advice on how to cure this situation is appreciated. Anyone else have this problem ? Maybe it is our gettydef setup ??? Thanks, Barry McInnes : barry@giaea.oz.au
georg@hpfcdc.HP.COM (Geri Georg) (09/21/90)
You can't turn off echoing in the HP-UX csh. The reason is two-fold. When csh is getting input, it turns off echoing and canonical processing. It then inputs characters one at a time, and does things like file expansion where necessary, depending on the character input. If the character is a regular character, it is then echoed "manually" by being output again to the standard output device by csh. Once the command is input, csh turns on echoing and canonical processing. So csh not only echos data back out (regardless of the tty setting), but it also turns on echoing in the tty setting. The reason the tty setting is reset to turn on echoing and canonical processing appears to be in order to recover in the case where a program terminates abnormally (or I guess normally but without restoring the tty) and leaves the tty in a basically unusable state. Resetting echoing and canonical processing avoids this problem. But as a result of the tty being reset by csh, there is no way to figure out if the user really wanted to turn off echoing, so there is no check that can be made in order to turn off the "manual" echoing which is done by csh. Geri Georg Hewlett-Packard
gates@hpfcdc.HP.COM (Bill Gates) (09/22/90)
Well, you've heard from the csh guru, and since I'm supposedly the sh guru, I'll respond next. :-) I can't duplicate this on 7.0 on either a 300 or an 800 SPU. Exactly how is echoing being reset for you using sh? I logged in, executed a sh, typed stty -echo, and presto - no echoing. An stty echo promptly restores things. Could you post a scenario which shows the failure? Bill