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Re: terminal goes funky

On 25-Jul-2000 Sven Burgener wrote:
> On Tue, Jul 25, 2000 at 04:38:32PM -0400, Dan Brosemer wrote:
>> > It seems to display things fine, but just with weird characters instead
>> > of proper ones. Some characters are fine though, like the "GNU" part of
>> > the login prompt. :)
>> Press ^V then ^O then ENTER at the prompt.
>> The system will echo back:
>> bash: ^O: command not found
> Yes! That's cool. Thanks.
>> You've just got the system to send a ^O character to the screen which will
>> reset it gracefully.
> Yes, but also ^V before the ^O, like you said.
> Do you know why? Anyone know why?

Each unix terminal has two charsets: a normal one, with the standard ascii
stuff, and a 'graphical' one, with those funny characters. The linux VT is no
exception from this, with two charset slots called G0 and G1. Switching between
carsets is done by sending the terminal the right control code. You can find
out what these are by disassembling the corresponding terminfo database (found
in /usr/share/terminfo) with infocmp(1). 
eg. 'terminfo linux > linux.ti' for the linux console. The "smacs" code is for
switching to the alternate charset, and the "rmacs" is for switching to the
normal one.
eg. in my linux.ti rmacs=^O and smacs=^N.

The ^V character is a property of the tty line. Just do a 'stty -a' and look
for the "lnext" code. This causes the next character to be sent literally to
the terminal, even if it's a control character.

So to switch to the 2nd carset type ^V^N, to switch back ^V^O.


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