Option / Meta key not working in Tmux

[matthewmturner]

I am using neovim and tmux (with tmuxinator) on my M1 Macbook with iTerm2 or Warp (https://www.warp.dev/) as my terminal (i had been using Warp primarily until this issue and saw lots of references to iTerm2 which i tried but still had issues with).

I have mapped my left option key to be my meta key in my terminal. I would like to use <M-h/j/k/l> in order to navigate between neovim splits and tmux panes. Mapping my left option key to meta and using it with h/j/k/l works as expected in neovim (including neovim in tmux - i.e. i can navigate neovim splits and go from neovim to a tmux terminal pane). However, in a tmux terminal pane it either does nothing in iTerm2 or brings up alternate text (˙∆˚¬ for hjkl to be specific) in Warp instead of switching panes or switching into nvim.

Below are my configurations which were from https://github.com/christoomey/vim-tmux-navigator and i just updated them to use meta instead of ctrl:

init.vim

let g:tmux_navigator_no_mappings = 1

nnoremap <silent> <M-h> :TmuxNavigateLeft<cr>
nnoremap <silent> <M-j> :TmuxNavigateDown<cr>
nnoremap <silent> <M-k> :TmuxNavigateUp<cr>
nnoremap <silent> <M-l> :TmuxNavigateRight<cr>
nnoremap <silent> <M-\> :TmuxNavigatePrevious<cr>

.tmux.conf

unbind M-h
unbind M-j
unbind M-k
unbind M-l

is_vim="ps -o state= -o comm= -t '#{pane_tty}' \
    | grep -iqE '^[^TXZ ]+ +(\\S+\\/)?g?(view|n?vim?x?)(diff)?$'"
bind-key -n 'M-h' if-shell "$is_vim" 'send-keys M-h'  'select-pane -L'
bind-key -n 'M-j' if-shell "$is_vim" 'send-keys M-j'  'select-pane -D'
bind-key -n 'M-k' if-shell "$is_vim" 'send-keys M-k'  'select-pane -U'
bind-key -n 'M-l' if-shell "$is_vim" 'send-keys M-l'  'select-pane -R'
tmux_version='$(tmux -V | sed -En "s/^tmux ([0-9]+(.[0-9]+)?).*/\1/p")'
if-shell -b '[ "$(echo "$tmux_version < 3.0" | bc)" = 1 ]' \
    "bind-key -n 'M-\\' if-shell \"$is_vim\" 'send-keys M-\\'  'select-pane -l'"
if-shell -b '[ "$(echo "$tmux_version >= 3.0" | bc)" = 1 ]' \
    "bind-key -n 'M-\\' if-shell \"$is_vim\" 'send-keys M-\\\\'  'select-pane -l'"

bind-key -T copy-mode-vi 'M-h' select-pane -L
bind-key -T copy-mode-vi 'M-j' select-pane -D
bind-key -T copy-mode-vi 'M-k' select-pane -U
bind-key -T copy-mode-vi 'M-l' select-pane -R
bind-key -T copy-mode-vi 'M-\' select-pane -l

Do I have the right configurations? If so, any insight on how I can get this working?

[christoomey]

Apologies but I don't have much familiarity around using option / meta for these (the few times I've dabbled in those keys for bindings in the past have been rough). I would expect this to work, and I don't see anything obviously wrong with your config, but also know this is a tricky space. Best of luck, and please do share if you sort anything out here (or if you happen to find that the plugin is in fact doing something wrong).

[matthewmturner]

@christoomey thank you for the quick response :) its at least good info to know that the config is ok. will let you know if i make any progress.

[matthewmturner]

@christoomey actually one more point. I only ended up using Meta because ctrl didnt work with ctrl-h. When I do that I get a message that says "No more marks available". The other three commands (j/k/l) work. Any idea on that?

[christoomey]

Sounds like you've got a conflicting mapping in Vim (the mention of "marks" makes me think it's Vim). You can check with verbose nmap <C-h> which likely will find whatever else might be trying to run for C-h

[leandrochiarini]

I have the same problem in Manjaro xfce, however, it seems like it is something bigger than the plugin, even if I try to remap
nnoremap <silent> <M-h> :echo "Hello Word"<CR>
it seems like vim does not trigger it. Even after removing everything from my .vimrc. Is it the same for you @matthewmturner?
By the way, this does not seem to be an issue in the insert mode, for instance.

[leandrochiarini]

In my case the general solution presented in StackExchange worked.

However, your problem seem to be well known for on OS X, does this answer solve your problem?

[Nugumanov]

I have the same issue using iTerm2 v3.4.15 using tmux (both v2.8 and v3) on MacOS Catalina 10.15
In iTerm settings I tried to switch between Left Option key as Normal and Meta, no effect
sed -n l shows nothing when pressing Option+key

[ksajan]

I have the same issue as @Nugumanov. Any other alternative @leandrochiarini ?

[ksajan]

I resolved this by changing the left Option key to Esc+ in preferences. @Nugumanov probably you can also try this if you still haven't found the solution.