Shell strangeness

Alex Tweedly alex at tweedly.net
Sat Feb 26 18:46:09 CST 2005


Mark Smith wrote:

> Idly playing around with shell commands, I noticed that I was getting 
> some quite strange return values.
> For example, below is the start of the text returned by 'put 
> shell("man bash") into fld 1'.
>
> -------------
>
> BASH(1)                                       BASH(1)
>
>
>
> NNAAMMEE
>        bash - GNU Bourne-Again SHell
>
> SSYYNNOOPPSSIISS
>        bbaasshh [options] [file]
>
> CCOOPPYYRRIIGGHHTT
>        Bash is Copyright (C) 1989-2002 by the Free Software 
> Foundation, Inc.
>
> DDEESSCCRRIIPPTTIIOONN
>        BBaasshh  is     an  sshh-compatible  command language 
> interpreter that executes
>        commands read from the standard input or from a file.  
> BBaasshh also incor-
>        porates useful features from the _K_o_r_n and _C 
> shells (kksshh and ccsshh).
>
>  -----------
>
> This doesn't happen in the terminal window. Not an important issue for 
> me, at the moment, but this sort of thing could be problematic I would 
> have thought.

It's (probably) a very old artifact - from the days of teletypes and 
similar. Some old Unixes would print man pages using "doubled" letters 
in the headers.

The "doubled" letters probably have some form of "backspace" between 
them - the effect on a teletype would be to overprint (i.e. effectively 
make 'bold') the doubled lines (or letters). 

The hidden (or lost) backspacing probably also happened on, for 
instance, the    _K_o_r_n    bit, to give underlined text.

-- 
Alex Tweedly       http://www.tweedly.net



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