[Bug]: vim sends a strange escape sequence when gnome-terminal is used

[tigran123]

Problem description

When vim is started up or exits, even without any file it displays a strange Unicode character, see the two screenshots.

What steps will reproduce the bug?

just run vim and then exit it via :q

What is the expected behavior?

There should be no garbage characters. Also, this only happens when I login via ssh from a Linux session running gnome-terminal, but if I login (again via ssh) from a Linux text console, then everything is fine -- no garbage is thrown by vim. I thought maybe something in my .vimrc/.viminfo is incompatible with vim (I normally use vim 8.0.3741, i.e. what is current on Ubuntu 18.04.6, so I moved those files out of the way, but no -- the problem is still there.

System information

termux-info:

Termux Variables:
TERMUX_APP_PACKAGE_MANAGER=apt
TERMUX_MAIN_PACKAGE_FORMAT=debian
TERMUX_VERSION=0.117
Packages CPU architecture:
aarch64
Subscribed repositories:
# sources.list
deb https://grimler.se/termux/termux-main stable main
Updatable packages:
All packages up to date
termux-tools version:
1.35.0
Android version:
10
Kernel build information:
Linux localhost 4.4.205-22915538 #1 SMP PREEMPT Mon Jul 25 09:40:28 KST 2022 aarch64 Android
Device manufacturer:
samsung
Device model:
SM-T835

[landfillbaby]

this is less a problem with vim and more one with gnome, that's a standard escape sequence being rendered as text...

[xtkoba]

Not reproducible for me, when SSHing from x11-terms/gnome-terminal-3.46.7 in Gentoo Portage. Those sequences are actually sent, but are handled correctly by my GNOME Terminal. Though it may [EDIT] not be of much help, I suggest sharing strace output of vim command, just in case.

A suggested workaround is to set TERM environment variable to something other than xterm (or xterm-256color.)

[landfillbaby]

OK, looking into it more, it's actually a slightly nonstandard code added by xterm to set its modifyOtherKeys level to 2, basically allowing raw keyboard input.
Related to vim's t_TE/t_TI variables, set by keyprotocol, and by default chosen from the TERM environment variable. Fixing it may be as simple as changing one of those.
https://vi.stackexchange.com/questions/27399/whats-t-te-and-t-ti-added-by-vim-8/ (slightly outdated as it doesn't account for keyprotocol in vim 9)
https://linux.die.net/man/1/xterm

What's your $TERM? if it's not gnome-256color or similar that's your problem.

[landfillbaby]

tl;dr you need to set TERM=gnome-256color. gnome doesn't support xterm stuff.

[xtkoba]

gnome-256color is not supported in Termux:

~ $ TERM=gnome-256color vim

E557: Cannot open termcap file
'gnome-256color' not known. Available builtin terminals are:
    builtin_ansi
    builtin_vt320
    builtin_vt52
    builtin_xterm
    builtin_iris-ansi
    builtin_pcansi
    builtin_win32
    builtin_amiga
    builtin_dumb
    builtin_debug
defaulting to 'ansi'

[xtkoba]

Note that it does not reproduce with my GNOME Terminal even when TERM=xterm-256color. I suspect that the version of GNOME Terminal is too old that the author is using.

[landfillbaby]

ah you're right yes. maybe we should add gnome terminfo files? or just leave ssh via old gnome unsupported

[xtkoba]

Adding terminfo is trivial and I will handle that.

[landfillbaby]

to clarify, the user should wait for #14409, pkg up in termux, then set TERM=gnome-256color when using ssh via outdated gnome, no matter the host.