Friday, August 31, 2012

Re: vim window clears the terminal history

On Fri, Aug 31, 2012 at 09:14:14AM EDT, joe M wrote:
> On Fri, Aug 31, 2012 at 1:27 AM, Chris Jones <cjns1989@gmail.com> wrote:
> > On Thu, Aug 30, 2012 at 01:34:10PM EDT, joe M wrote:

[..]

> Hope the above helps. Please let me know if you need more information.

I'm not an expert in Vim or termcap/terminfo by a long way... :-)

I'm still not sure you are actually executing the code you compiled, but
I'll trust you on that. If you are confident the executables in /bin and
/usr/bin are the ones you compiled yourself, I nevertheless suggest you
run all your tests invoking them via their full path (/usr/bin/vim and
/bin/vi).

I also thought that a possible explanation of the inconsistent behavior
might be caused by the fact that 'vi' was using termcap and 'vim' was
using terminfo.. and that there might be escape sequence discrepancies
between the two on your system --something that I believe should not
happen, since a given terminal's capabilities remain the same and its
termcap and terminfo escape sequences should therefore be identical.

Another thing: _my understanding_ is that when both terminfo and termcap
are implemented, Vim chooses terminfo 'automatically' at configure time.
cf. :help startup-terminal.

And then there is the fact that I see '+terminfo' in the output of both
the 'vi --version' and the 'vim --version' that you pasted in your
previous post. (cf. :h +terminfo).

Besides, 'man 5 termcap' has the following: 'The termcap database is an
obsolete facility for describing the capabilities of character-cell
termi‐ nals and printers. It is retained only for capability with old
programs; new ones should use the ter‐ minfo(5) database and associated
libraries.'

Don't see any good reason Vim would use an 'obsolete facility' unless it
had to.

In no particular order, a few additional questions/remarks that might
help clarify:

1. What distribution are you running?

2. Did you run the default version of vi/vim before you compiled your
own from source?

3. If so, are you positive you removed the prior version?

4. Not suggesting a workaround, but did you try running the same test on
a different terminal.. & see what happens..? xterm is probably already
installed on your system¹, if not, you could also try good ole rxvt?

5. Conversely, how about temporarily removing your compiled version and
installing your distro's default version and running a test. If the
problem goes away, this might suggest that the different behavior is
caused by one of the --enable-option that you specify at ./configure
time..?

6. Would it make sense to generate both executables using the same
./configure options.. check whether you still have the problem?

7. Just in case, is there a TERMCAP environment variable exported to
your terminal session before you run vi/vim:

% env | grep TERMCAP

8. As to builtin terminals.. I'm still running vim 7.2 and when I do
a ':set term=xxx' there is no mention of urxvt or rxvt in my list of
builtin terminals. Is this also what happens with vim 7.3?

9. Is termcap implemented on your system? On debian I apparently have it
as part of the libncurses5-dev package.

Naturally, the above are not really meant as questions, but rather,
stuff I would ask myself if I had the same problem and that might help
investigate².

CJ

¹ Note that in the case of xterm, you can {en/dis}able the alternate
screen capability by holding down the CTRL key and middle-clicking:
This brings up a menu where you can check/uncheck 'Enable alternate
screen switching'.

² As to the disappearing lines, (the 'seq 1000' test), when I disable
alternate screen switching, I find that roughly one screen worth of
numbers are overwritten by the Vim screen that remains visible after
I exit. I have something like 91 lines on my terminal and when
I scroll back, the last number I see is 909.. immediately followed by
the last visible contents of the Vim session --i.e. if I was looking
at an empty buffer, I see a bash prompt, then vim's tabline, followed
by a number of empty lines and then the status line and lastly my bash
prompt at the bottom of the screen. I would imagine this is expected
behavior (?).

--

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