syscons features

[Charles Swiger]

On Jun 22, 2005, at 2:52 PM, Steven Friedrich wrote:
> Can anyone explain to me the mechanism behind the following:
>
> If I echo B^HB | more
>
> I get a bold B.  more is somehow activating? a feature of syscons  
> (or the vga
> driver).
>
> Are there any other utilities like more that do this?  Is this  
> behavior
> documented in a man page ?

Yes.  From "man less" (your more is probably really less):

        -U or --UNDERLINE-SPECIAL
               Causes  backspaces,  tabs  and carriage returns to be  
treated as
               control characters; that is, they are handled  as   
specified  by
               the -r option.

               By  default,  if  neither  -u  nor -U is given,  
backspaces which
               appear adjacent to an  underscore  character  are   
treated  spe-
               cially:  the  underlined  text is displayed using the  
terminal's
               hardware underlining capability.  Also, backspaces  
which  appear
               between  two  identical  characters  are  treated  
specially: the
               overstruck text is printed using the terminal's   
hardware  bold-
               face  capability.   Other backspaces are deleted,  
along with the
               preceding character.  Carriage returns immediately  
followed by a
               newline  are  deleted.   other  carriage  returns are  
handled as
               specified by the -r option.  Text which is overstruck  
or  under-
               lined can be searched for if neither -u nor -U is in  
effect.

This is using the $TERM setting via termcap or terminfo.

-- 
-Chuck