Home and End keys not working in Tmux and TERM=screen-256color

[frol]

• nvim --version: v0.2.2
• Vim (version: 8.0.1476) behaves as expected (in contrast to neovim)
• Operating system/version: Arch Linux (Gnome 3)
• Terminal name/version: tmux 2.6 in Gnome Terminal 3.26.2
• $TERM: screen-256color

Steps to reproduce using nvim -u NORC

nvim -u NORC
i1234<ESC><HOME>

Actual behaviour

<HOME> (and <END>) doesn't put the cursor to the beginning of the line while <CTRL>+<HOME> works fine (moves the cursor to the beginning of the file).

Expected behaviour

<HOME> should put the cursor to the beginning of the line.

Extra notes

I have read the related issues (#4308 and #6014) and FAQ on this matter, but given that I already have TERM=screen-256color, they didn't help.

In the same session, vim works as expected.

I have tried setting TERM to xterm-256color, xterm, and screen and it turned out that screen value fixes the issue with <HOME> / <END> buttons, but it doesn't seem correct to me, so I decided to report it.

I want to also note that everything used to work just fine up until a few days ago, and I haven't touched any configs and I don't recall updates either to neovim nor tmux, but the fact that everything but neovim works just fine forced me to write this issue just in case if I am not alone.

Any idea on how I can inspect the issue?

[mhinz]

Does TERM=tmux-256color make a difference?

[frol]

@mhinz TERM=tmux-256color doesn't help, but TERM=tmux does the trick just like TERM=screen.

[mhinz]

The next release will automatically use a built-in terminfo entry if tmux is detected but $TERM is not tmux-256color. That should avoid such issues.

Tmux used to use screen and screen-256color in the past because it was widely available. But it was still meant for screen. Modern ncurses versions ship with tmux and tmux-256color.

[justinmk]

I want to also note that everything used to work just fine up until a few days ago

#8027

[frol]

@justinmk Oh, thank you! Sorry for the duplicate.

I confirm that unibilium 2.0 fixes the issue (installed from the community-testing Arch repo)

[cemeyer]

Hm, the autodetection seems kind of broken in GNU screen:

nvim: 0.4.2
unibilium: 2.0.0
term: terminology 1.4.1
screen: 4.7.0

.screenrc: term screen-256color

Outside screen: TERM is xterm, HOME/END keys work in nvim.

Inside screen: TERM is screen-256color, HOME/END keys do not work. It seems nvim ignores TERM? From an example in 7798,

nvim -V3log
:q

Shows:

--- Terminal info --- {{{
&term: builtin_xterm
Description: xterm with 256 colors
Aliases: xterm-256color
...

With the wrong (xterm) codes for key_home and key_end. infocmp in the same screen session shows the correct kend and khome sequences.

Why does nvim think it knows better than my (correct) $TERM? Here's the wrinkle: XTERM_256_COLORS=1 (set by terminology, I guess) is inherited, for shells inside screen. And apparently that overrides TERM for nvim's purposes.

unset XTERM_256_COLORS ; nvim -V3log ⇒

--- Terminal info --- {{{
&term: builtin_screen
Description: GNU Screen with 256 colors
Aliases: screen-256color

So... I can hack around this with unsetenv XTERM_256_COLORS in .screenrc. But I wonder if ignoring TERM if XTERM_256_COLORS is set is really the right thing to do here?

Edit: and even when it correctly infers builtin_screen, Home/End keys are still broken. Ugh.

&term: builtin_screen
...
  key_home                  khome      = <Esc>[1~
  key_end                   kend       = <Esc>[4~

$ infocmp | grep ...
        kdch1=\E[3~, kend=\E[4~, kf1=\EOP, kf10=\E[21~,
        khome=\E[1~, kich1=\E[2~, kmous=\E[M, knp=\E[6~, kpp=\E[5~,

$ showkey --scancodes
...
<ESC>[1~<ESC>[4~     # Pressed Home, then End

So everything seems to line up, but nvim still isn't handling home/end correctly?

Edit2: Ah, FreeBSD is still on the dead mauke unibilium fork. I have filed https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=242560 . Hopefully that addresses the issue I'm seeing.