Re: terminal

[Theo de Raadt <deraadt@cvs.openbsd.org>]

This is terrible advice.

Use the ioctl.

> On December 1, 2002 07:03 am, Hugo Villeneuve wrote:
> > On Sat, Nov 30, 2002 at 11:45:27AM -0800, Ben Bunker wrote:
> > > Hello,
> > >
> > > Bit of a programming question here.  I'm attempting to
> > > write a scaled-down version of the more utility, and
> > > I'm at a loss as to how to find the size of the
> > > terminal (i.e., width, number of lines).  Does anyone
> > > have any insight into this?  Thanks.
> >
> > There's a TIOCGWINSZ ioctl to get the window size (man 4 tty).
> 
> Assuming the user has set it right. ;-)
> 
> The low level method of this is to send a terminal capabilities inquiry 
> code to some terminals or terminal software. But inquiry code 
> emulation in the more marginal terminal emulations is hit or miss.
> And the parsing logic can get ugly. Or....
> 
> The portable way of doing it (given that everything except ancient crusty
> wyse magic cookie terminals accepts ANSI/VT codes) sounds ugly but 
> works nicely: The technique is to gradually send incrementing screen 
> positions {printf("\x1B[%d;%dH]",x,y);} and use the return character pos 
> inquiry code {printf("\x1B[6n");} and parse out the returned "\x1B[%d;%dH" 
> sequences until it's obvious you've hit the end of the screen because 
> they stop incrementing.
> 
> This method works even with very broken terminal emulation sw and should 
> be as close to universally applicable as I've found. 
> 
> cheers
> --dr
> 
> P.S. Join the campaign to remove terminfo and termcap from POSIX today!!!
> s/term{info,cap}/ansi/  :-)
> 
> P.P.S. Less is often more better. :-) :-) :-)
> 
> -- 
> dr@kyx.net   pgp: http://dragos.com/kyxpgp
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