<C-h> (CTRL-H) does not work in the new TUI

[rainerborene]

I use the following mappings on my .nvimrc and it does not work using tmux inside urxvt.

nnoremap <C-h> <C-w>h " only C-h does not work.
nnoremap <C-j> <C-w>j
nnoremap <C-k> <C-w>k
nnoremap <C-l> <C-w>l

env output

BROWSER=firefox
COLORFGBG=7;0
COLORTERM=rxvt
DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-zNeYXuznrs,guid=844332d151bf76af0ebfba3754e5f937
DESKTOP_SESSION=i3
DESKTOP_STARTUP_ID=i3/i3-sensible-terminal/725-0-arch_TIME89282
DISPLAY=:0
DOCKER_HOST=unix:///var/run/docker.sock
EDITOR=vim
GDMSESSION=i3
GDM_LANG=en_US.utf8
GPG_TTY=/dev/pts/5
GREP_COLOR=97;45
GTK_MODULES=canberra-gtk-module
HG=/usr/bin/hg
LANG=en_US.utf8
LC_MEASUREMENT=pt_BR.utf8
LC_MONETARY=pt_BR.utf8
LC_NUMERIC=pt_BR.utf8
LC_PAPER=pt_BR.utf8
LC_TIME=pt_BR.utf8
LS_COLORS=no=00;37:fi=01;34:di=00;34:ln=00;36:pi=40;33:so=00;35:do=00;35:bd=40;33;01:cd=40;33;01:or=00;05;37;41:mi=00;05;37;41:su=37;41:sg=30;43:tw=30;42:ow=04;34:st=37;44:ex=00;32:*.cmd=00;33:*.exe=00;33:*.com=00;33:*.btm=00;33:*.bat=00;33:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lz=01;31:*.xz=01;31:*.bz=01;31:*.bz2=01;31:*.bzip2=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.rar=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.apk=01;31:*.gem=01;31:*.jpg=00;35:*.JPG=00;35:*.jpeg=00;35:*.gif=00;35:*.bmp=00;35:*.pbm=00;35:*.pgm=00;35:*.ppm=00;35:*.tga=00;35:*.xbm=00;35:*.xpm=00;35:*.tif=00;35:*.tiff=00;35:*.png=00;35:*.svg=00;35:*.svgz=00;35:*.mng=00;35:*.pcx=00;35:*.dl=00;35:*.xcf=00;35:*.xwd=00;35:*.yuv=00;35:*.cgm=00;35:*.emf=00;35:*.eps=00;35:*.CR2=00;35:*.ico=00;35:*.pdf=00;32:*.ps=00;32:*.txt=00;32:*.html=00;32:*.rst=00;32:*.md=00;32:*.patch=00;32:*.diff=00;32:*.tex=00;32:*.doc=00;32:*.xml=00;32:*.xls=00;32:*.xlsx=00;32:*.doc=00;32:*.docx=00;32:*.ppt=00;32:*.pptx=00;32:*.key=00;32:*.pt=01;32:*.tmpl=01;32:*.in=01;32:*.aac=01;36:*.au=01;36:*.flac=01;36:*.mid=01;36:*.midi=01;36:*.mka=01;36:*.mp3=01;36:*.mpc=01;36:*.ogg=01;36:*.ra=01;36:*.wav=01;36:*.m4a=01;36:*.axa=01;36:*.oga=01;36:*.spx=01;36:*.xspf=01;36:*.mov=01;36:*.mpg=01;36:*.mpeg=01;36:*.m2v=01;36:*.mkv=01;36:*.ogm=01;36:*.mp4=01;36:*.m4v=01;36:*.mp4v=01;36:*.vob=01;36:*.qt=01;36:*.nuv=01;36:*.wmv=01;36:*.asf=01;36:*.rm=01;36:*.rmvb=01;36:*.flc=01;36:*.avi=01;36:*.fli=01;36:*.flv=01;36:*.gl=01;36:*.m2ts=01;36:*.divx=01;36:*.webm=01;36:*.axv=01;36:*.anx=01;36:*.ogv=01;36:*.ogx=01;36:*.conf=00;36:*.cnf=00;36:*.cfg=00;36:*.ini=00;36:*.properties=00;36:*.yaml=00;36:*.vcl=00;36:*.c=00;33:*.cpp=00;33:*.py=00;33:*.coffesscript=00;33:*.js=00;33:*.rb=00;33:*.sh=00;33:*.zsh=00;33:*.env=00;33:*.bash=00;33:*.php=00;33:*.java=00;33:*.zcml=00;33:*.db=00;32:*.sql=00;32:*.json=00;32:*.plist=00;32:*.fs=00;32:*.tex=01;37:*.rdf=01;37:*.owl=01;37:*.n3=01;37:*.ttl=01;37:*.nt=01;37:*.torrent=01;37:*.xml=01;37:*Makefile=01;37:*Rakefile=01;37:*build.xml=01;37:*rc=01;37:*.nfo=01;37:*README=01;37:*README.txt=01;37:*readme.txt=01;37:*README.markdown=01;37:*README.md=01;37:*.ini=01;37:*.yml=01;37:*.cfg=01;37:*.conf=01;37:*.c=01;37:*.cpp=01;37:*.cc=01;37:*.log=01;30:*.bak=01;30:*.aux=01;30:*.lof=01;30:*.lol=01;30:*.lot=01;30:*.out=01;30:*.toc=01;30:*.bbl=01;30:*.blg=01;30:*~=01;30:*#=01;30:*.part=01;30:*.incomplete=01;30:*.swp=01;30:*.tmp=01;30:*.temp=01;30:*.o=01;30:*.obj=01;30:*.pyc=01;30:*.pyo=01;30:*.class=01;30:*.cache=01;30:*.egg-info=01;30:
MOZ_PLUGIN_PATH=/usr/lib/mozilla/plugins
SHELL=/usr/bin/fish
SHLVL=4
SSH_AGENT_PID=746
SSH_AUTH_SOCK=/tmp/ssh-J6jf9XAbiTjD/agent.725
TERM=screen-256color
TERMINFO=/usr/share/terminfo
TMUX=/tmp/tmux-1000/default,1161,11
TMUX_PANE=%27
WINDOWID=23068681
WINDOWPATH=1
WINEARCH=win32
XDG_RUNTIME_DIR=/run/user/1000
XDG_SEAT=seat0
XDG_SESSION_DESKTOP=i3
XDG_SESSION_ID=c2
XDG_VTNR=1
__fish_bin_dir=/usr/bin
__fish_datadir=/usr/share/fish
__fish_help_dir=/usr/share/doc/fish
__fish_runtime_dir=/run/user/1000
__fish_sysconfdir=/etc/fish
fish_greeting=

[jwkvam]

I experience the same on OSX with iterm2.

[tarruda]

what is displayed if you type <c-v><c-h> in insert mode?

[jwkvam]

With nvim, Commit: 0df6b91
<BS>
With vim 7.4.488
^H
I'm using the same config for both vim and neovim.

[rainerborene]

Same here. <BS>

[tarruda]

any chance you compiled against the wrong libtermkey version? Does rm -rf .deps build && make && build/bin/nvim change anything?

[jwkvam]

Same behavior for me.
- downloading... src='https://github.com/neovim/libtermkey/archive/8c0cb7108cc63218ea19aa898968eede19e19603.tar.gz'

[tarruda]

what is displayed when you press ctrl+h in the cat program?

[jwkvam]

^H, the same happens with xxd.

[foobacca]

I use <C-h> for gT (move to tab left) and just tested and it works as expected. And <c-v><c-h> shows ^H

I'm using the PPA version of nvim - tried 0.0.0+git201502201750+6ubuntu14.04.1 and 0.0.0+git201502221955+6ubuntu14.04.1 - both work fine.

I run in tmux in terminator on Ubuntu.

[jwkvam]

FWIW, I bisected the merges and it broke at merge #2039

[tarruda]

@jwkvam that PR didn't change anything related to parsing these keys: https://github.com/neovim/neovim/pull/2039/files

As I said, there was a problem with how libtermkey handled ctrl+h or backspace, but it was fixed in a recent commit: neovim/libtermkey@619c0c1

[geoffharcourt]

Experiencing the same problem on the latest build (61c98e7). I'm in iTerm, and the problem happens both inside and outside of tmux. <c-v><c-h> prints <BS>.

[geoffharcourt]

One further detail: this problem happens in nvim with a blank .vimrc.

[acoffman]

I'm experiencing exactly this same problem.
It happens on a totally clean install with no plugins:

The entire contents of my .nvimrc are

" navigate splits
nmap <silent> <C-k> :wincmd k<CR>
nmap <silent> <C-j> :wincmd j<CR>
nmap <silent> <C-h> :wincmd h<CR>
nmap <silent> <C-l> :wincmd l<CR>

I'm using OSX 10.10.2 with iTerm2 and NVIM 0.0.0-alpha+201502261923. The problem occurs both inside and outside of tmux and also in Terminal.app. All three other bindings work, but <C-h> does not.

[acoffman]

Oh, and <c-v><c-h> in insert mode prints <BS> in the current buffer.

[adambiggs]

Same thing here. Default left-navigation key mapping for the vim-tmux-navigator plugin is broken.

iTerm on OSX 10.10.2. With & without Tmux. Also broken in Terminal.app. Works fine in terminal MacVim.

[lambdahands]

Experiencing this as well.

iTerm on OSX 10.10.2

[af]

I'm also fighting with trying to bind <C-h>. iTerm2 on OS X 10.10.2, using NVIM-0.0.0-alpha+201503020458.

It's not a good solution, but if you're looking for a workaround, replacing <C-h> with <bs> in my mappings did the trick for me (assuming you don't use the backspace key).

[geoffharcourt]

I think we have enough reports now no one else needs to confirm there's a problem, so no further need to add on to this thread.

[kopischke]

@tarruda as everybody concerned seems to be using OS X, this (somewhat elderly) post might be relevant: it suggests that OS X terminals are defining a different erase character than Linux in the xterm terminfo, thus causing occasional issues with Backspace / Ctrl-h (which is the backspace equivalent when you use Emacs readline keybindings).

[ladislas]

Another alternative is to use <C-w-h> which does the trick for me :)

[ZyX-I]

@ladislas What is w modifier? Win key?

[ladislas]

@ZyX-I my bad, it's <C-w>h which means you have to presse the Ctrlkey + w letter key + h letter key.

It's just from the remap actually... nnoremap <C-h> <C-w>h

[LuRsT]

@kopischke, I wasn't going to chime in since there are already a lot of reports for this bug, but I just wanted to add that I'm experiencing the same on Arch linux (Using the AUR package which may be outdated)

Update: I don't have this problem in Ubuntu (using the package from apt-get)

[fishman]

i'm in archlinux too. this must be because of one the terminal libraries.

in nvim c-h produces <BS> whereas in vim in produces ^H

EDIT: and i've built it manually too, just in case the versions might cause a problem. i also tried it in xterm to see if the issue is rxvt specific

 if has('nvim')
     nmap <BS> <C-W>h
 endif

works for example. though that's a terrible workaround

[blueyed]

FWIW, I've found this in tmux source:

/*
 * Check for backspace key using termios VERASE - the terminfo
 * kbs entry is extremely unreliable, so cannot be safely
 * used. termios should have a better idea.
 */
bspace = tty->tio.c_cc[VERASE];
if (bspace != _POSIX_VDISABLE && (key & KEYC_MASK_KEY) == bspace)
    key = (key & KEYC_MASK_MOD) | KEYC_BSPACE;

https://github.com/tmux/tmux/blob/fe4e9470bb504357d073320f5d305b22663ee3fd/tty-keys.c#L625-L632

And it gets set for panes initially: tio2.c_cc[VERASE] = '\177'; (https://github.com/tmux/tmux/blob/fe4e9470bb504357d073320f5d305b22663ee3fd/window.c#L866).

Not sure if it's really helpful, but might give some idea to fix this.

[justinmk]

@blueyed Yes, that's the traditional way to avoid this issue (Vim uses the same approach): fall back to termios. We would like to do that, but it requires forking libtermkey (or more ideally, getting a hook in libtickit when libtermkey is merged into libtickit).

[dojoteef]

I know I'm late to the party, but if anyone is looking for a solution with a more limited scope the approach I used will gracefully fallback to termios settings if needed for your terminal without requiring a global setting.

https://github.com/dojoteef/dotfiles/blob/master/init/50_nvim.sh#L39
https://github.com/dojoteef/dotfiles/blob/master/source/50_editor.sh#L4

[justinmk]

For those finding this issue, :CheckHealth now detects this problem and suggests a workaround. The same workaround is mentioned in the FAQ.

---

Update: @blueyed post to ncurses mailing list: https://lists.gnu.org/archive/html/bug-ncurses/2016-11/msg00022.html

---

Update: #5758 is an attempt to fix this issue.

[justinmk]

This is fixed on master (not released yet). To build from source, you probably need to:

rm -rf .deps build

However master is unstable currently, so most users should wait until the next release.