Left/right arrow and backspace translation confusion

[Doug Lee]

This one is making me feel dumb...I've been using FreeBSD for at least
six years but I can't seem to figure this out...

I have two FreeBSD systems running 4.10/4.11 (these problems have
plagued me through several versions though).  On one system, arrows
and backspace work as expected, but on the other, left/right arrows in
vi cause havock (extra characters and a switch from command to insert
mode), and backspace in Lynx, Mutt, etc., backs up but leaves
characters intact instead of clearing them.  I have verified that the
following are identical on both systems:

- termcap (/etc symlink and /usr/share/misc/termcap and termcap.db).
- ~/.exrc.
- stty settings at run time and as set in ~/.login (I use tcsh).
- .screenrc (I also use screen 4.00.02 on both systems).
- /usr/local/etc/screenrc

I have also tried connecting to each system directly, via a serial
cable and via a Telnet client; and also connecting to each system
through an ssh session on the other one, inside a Screen session.
The results are always the same:  On one system, keys work as
expected, but on the other, they always work in the same wrong way.

Actually, I find that the problem only occurs when I'm inside a Screen
session on the troublesome system.  In other words, all variations
above work properly if I'm not in Screen on the troublesome system
(even if I'm connected to it through a Screen session running ssh on
the other system), but all above variations involving my being in a
Screen session on the troublesome system cause the problem.

In case it helps, here's sort of a truth table, where s2 is the
troublesome system:

Serial to s1: ok
Serial to s1 screen session: ok
Serial to s2: ok
Serial to s2 screen session: problem

Telnet to s1: ok
Telnet to s1 screen session: ok
Telnet to s2: ok
Telnet to s2 screen session: problem

Serial or Telnet through s1 screen session to s2: ok
Serial or Telnet through s1 screen session to s2 screen session: problem
Serial or Telnet through s2 screen session to s1: ok
Serial or Telnet through s2 screen session to s1 screen session: ok!


Any help will be most appreciated.  Please Cc me with replies.  I feel
like I'm missing something very basic here...


-- 
Doug Lee           dgl at dlee.org        http://www.dlee.org
BART Group         doug at bartsite.com   http://www.bartsite.com
"While they were saying among themselves it cannot be done, it was
done." --Helen Keller