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Re: arrow keys in the console


From: Tim X
Subject: Re: arrow keys in the console
Date: Sat, 19 May 2007 13:03:31 +1000
User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.99 (gnu/linux)

Tyler Smith <address@hidden> writes:

> On Fri, May 18, 2007 at 04:00:30PM +0200, Peter Dyballa wrote:
>> 
>> Am 18.05.2007 um 14:16 schrieb Tyler Smith:
>> 
>> >echo $TERM now shows: linux. How do I find out what it should be?
>> 
>> tset - -Q or such can determine the right value. It also would work  
>> to set it xterm or xterm-color. This kind of terminal is supported by  
>> GNU Emacs. Look into lisp/term directory!
>> 
>
> Thanks! Setting TERM=xterm seems to have fixed it!
>

This is likely to cause you all sorts of 'weird' issues. In particular, it will
almost certainly screw up some terminal programs, which will now think they are
running under an X terminal with all that implies re: keycodes and modifiers,
mouse and cutting/pasting, colour mappings etc. Some programs will use the TERM
setting to work out what environment they are running under to determine what
features to load or make available. Having this set to xterm will confuse these
programs. 

The correct solution is to load the right keymap. You can even setup a keymap
so that additional keys, like the 'windows' keys are mapped to something like
'super' or 'hyper', which gives you a whole new set of modifiers to take
advantage of. You can also redefine keys, such as swapping caps lock and
control, which some people like because its easier on the fingers etc. 

Part of the reason that its a bad idea to just 'fool' the system by setting
TERM to xterm when running under the Linux text console is because normally, X
has a translation layer that affects the values seen by programs when a key is
pressed. The Linux console doesn't use the same scheme (mainly because it
pre-dates a lot of the 'extended' keyborad functionality and because much of
that functionality has no applicability in a text console). The extent to which
any of this has any impact depends on where/how the program is geting its
values. Any programs that use very low level functions to process keyboard
input are likely to behave weirdly with an incorrect TERM setting. Part of this
is because the TERM setting essentially points to a database that describes the
capabilities of the terminal your running under. While there is a lot of
similarity between the Linux console and an xterm, they are not the same - for
one thing, you cannot resize a Linux console. You are also likely to see
probems if you use ssh to connect to a remote server as this server will be
told that yo are running from an X term and will assume you have X capabilities 
etc.

In short, while it may appear to be working, its likely to have subtle
side-effects and is technically incorrect. The correct solution is to set the
correct keymap.

Tim

-- 
tcross (at) rapttech dot com dot au


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