Re: less doesn't recognize capabilities of remote terminal

[Gary Johnson <garyjohn at spk dot agilent dot com>]

On 2007-02-05, Gary Johnson wrote:
> I recently got Cygwin's sshd running on my Windows XP machine.  It 
> seems to basically work fine, allowing me to login from any of 
> several machines running various flavors of Unix.  Cygwin's less
> command, however, doesn't seem to recognize the capabilities of my 
> remote terminal.
> 
> For example, I often use ssh to login to my Windows machine from 
> another machine running SunOS 5.8, using an xterm version "XFree86 
> 4.1.0(165)".  When I use less to read a file, I get a warning
> message:
> 
>     $ less /usr/share/doc/Cygwin/terminfo-5.5_20061104.README
>     WARNING: terminal is not fully functional
>     /usr/share/doc/Cygwin/terminfo-5.5_20061104.README  (press RETURN)

Update:  If I simply set TERM=xterm (instead of xterm-16color), less 
works fine:

    TERM=xterm less /usr/share/doc/Cygwin/terminfo-5.5_20061104.README

The difference between the two terminfo entries is:

    $ infocmp xterm xterm-16color
    comparing xterm to xterm-16color.
        comparing booleans.
        comparing numbers.
            colors: 8, 16.
            pairs: 64, 256.
        comparing strings.
            setab: '\E[4%p1%dm', '\E[%?%p1%{8}%<%t%p1%'('%+%e%p1%{92}%+%;%dm'.
            setaf: '\E[3%p1%dm', '\E[%?%p1%{8}%<%t%p1%{30}%+%e%p1%'R'%+%;%dm'.
            setb: '\E[4%?%p1%{1}%=%t4%e%p1%{3}%=%t6%e%p1%{4}%=%t1%e%p1%{6}%=%t3%e%p1%d%;m', '%p1%{8}%/%{6}%*%{4}%+\E[%d%p1%{8}%m%Pa%?%ga%{1}%=%t4%e%ga%{3}%=%t6%e%ga%{4}%=%t1%e%ga%{6}%=%t3%e%ga%d%;m'.
            setf: '\E[3%?%p1%{1}%=%t4%e%p1%{3}%=%t6%e%p1%{4}%=%t1%e%p1%{6}%=%t3%e%p1%d%;m', '%p1%{8}%/%{6}%*%{3}%+\E[%d%p1%{8}%m%Pa%?%ga%{1}%=%t4%e%ga%{3}%=%t6%e%ga%{4}%=%t1%e%ga%{6}%=%t3%e%ga%d%;m'.

(The setb and setf lines are really long and may have wrapped
horribly.)  What any of those strings has to do with scrolling, I
don't know.  The xterm-16color entries for setb and setf look
suspicious to me since neither starts with \E.

That xterm-16color terminfo is from Cygwin's /usr/lib/terminfo.  The
xterm-16color terminfo from the xterm-165 release that I have on the
Sun machine is different, but its setb and setf strings also lack
the leading \E's.  The same is true for the xterm-16color terminfo
from a Red Hat Linux 9 machine with xterm-174.

This is just a guess, but I wonder if the setb and setf entries are
long-standing errors in the xterm terminfo data that haven't been
detected because applications use setab and setaf instead.  But then
why does only Cygwin's less complain?

Regards,
Gary

-- 
Gary Johnson                 | Agilent Technologies
garyjohn@spk.agilent.com     | Wireless Division
                             | Spokane, Washington, USA

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