Curses problem with keymapping in screen and debugging curses

Derek Ragona derek at
Thu Feb 14 19:20:02 UTC 2008

At 12:06 PM 2/14/2008, Martin Cracauer wrote:
>I have the following problem when using screen sessions between
>FreeBSD and Linux:
>The pageup/pagedown keys stop working when I re-attach a session that
>was started under FreeBSD to a console that is Linux driven and vice
>versa.  All other keys, including alt/meta and some supposedly more
>complicated keys continue to work.  I haven't verified this in detail
>but it seems that while programs like mutt seem affected often emacs
>seems to be happy.
>I know NIL about curses.  How would I go about debugging this? I would
>need something like "xev" for curses to see what keys I get from the
>different consoles and then I'd need something to find out what a
>given session expects.
>Where do I start looking?
>Also, I see screen on FreeBSD emit line noise on a regular basis, both
>when attaching before the session comes up and after deattaching.
>Dunno whether this helps.  Example:
># session running, press detach key
>-en \033]0; grisu:ttype:~\007


In the past I have had issues with reading some keys with curses too.

I would read the keys and if they were unknown I'd print out the value.  I 
used a large case statement and if the key fell through I printed out the 

You also need to remember in curses most of the extra keys, function and 
movement keys are compound sequences where first ESC is sent, then the 
actual keycode is in the next two bytes.  You have to get those two bytes 
and put them together to decode the actual keycode.

You can debug your program in any debugger, I used xxgdb from the ports.


This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.

More information about the freebsd-questions mailing list