Re: agetty and special chars @ and #

[Karel Zak <kzak@redhat.com>]

On Mon, Nov 12, 2012 at 11:04:11AM +0100, Dr. Werner Fink wrote:
> On Wed, Nov 07, 2012 at 05:58:59PM +0100, Karel Zak wrote:
> > 
> >  Hi Werner,
> > 
> >  agetty in get_logname() interprets '@' and '#' as a special chars
> >  (see man page or the code for more details).
> > 
> >  The problem is that we already have crazy users who want to use AD
> >  (access domain) usernames in format user@domain on serial line or
> >  console.
> > 
> >  Yeah, I know that char '@' is not between allowed username chars
> >  (POSIX 3.429), but do we really need to support the spacial
> >  interpretation of the @ and # chars?
> > 
> >  I think it's old confusing legacy. Objections?
> 
> Hmmm ... AFAICR the '@' symbols can be used to set the kill character
> and the '#' can be used to set the erase character.  But for a virtual
> console terminal those characters those are normally not used.
> 
> Only connections at dialin as well connections over some serial lines
> with hardware/software line routers/terminal servers between this could
> be problem.  On big irons such serial lines are used even in the present
> days.
> 
> Maybe it would be worth to introduce an further option to support
> access domains in user names ... or the other way around to support
> '@' and '#' as special characters used for software escapes on
> oldish connection lines.

 I thought about something like:

    --erase-chars <string>
    --kill-chars  <string>

 and if the string is empty then agetty is insensitive to the special
 chars. This should be a default for virtual console (or also for
 serial line?).

 vice versa

   agetty --erase-chars '#'

 enables the support for the char.

 IMHO this solution is easy to extend (you can use another chars) and
 provides full control of the feature (you can disable it at all).

    Karel

> 
> 
>    Werner
> 
> http://www.linusakesson.net/programming/tty/
> http://digilander.libero.it/robang/rubrica/serial.htm
> 
> -- 
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-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com