This is all in iTerm2 on OS X.

I used to have

export TERM='xterm-256color'

in my .bashrc. This meant Vim in tmux did use 256 colors.

And once I added

set -g xterm-keys on

then keyboard shortcuts with modifiers worked fine in Vim. Namely: shift+left/right that I mapped to switch Vim tabs, ctrl+up/down that I mapped to move ("bubble") lines, and shift+left/right which worked out of the box to jump by word in the command-line mode (e.g. when typing something like :e foo bar baz).

However, this setup had the problem that the Vim background color only shows behind text, as mentioned here.

So I removed

export TERM='xterm-256color'

from my .bashrc and instead put this in my .tmux.conf:

set -g default-terminal "screen-256color"

That fixed the Vim background color, but broke the keyboard shortcuts - they do unexpected things (move the cursor, delete text) instead.

By using ctrl+v to insert the verbatim output from the key combinations (as described here), I was able to work around it:

map [1;5A <C-Up>
map [1;5B <C-Down>
map [1;2D <S-Left>
map [1;2C <S-Right>
cmap [1;2D <S-Left>
cmap [1;2C <S-Right>

This makes the shortcuts work, but it doesn't feel like the right solution. Could anyone tell me what's happening here and how to fix it?

2 Answers 2


You need to set the tmux window option xterm-keys so that tmux will pass these keys through to its terminals. You probably want to put this in your ~/.tmux.conf:

set-window-option -g xterm-keys on

Vim will usually automatically set up its handling of these keys when TERM is xterm-something, but it skips this since TERM is screen-256color. You can manually configure these keys in your ~/.vimrc like this:

if &term =~ '^screen'
    " tmux will send xterm-style keys when its xterm-keys option is on
    execute "set <xUp>=\e[1;*A"
    execute "set <xDown>=\e[1;*B"
    execute "set <xRight>=\e[1;*C"
    execute "set <xLeft>=\e[1;*D"

At least that way you do not have to map all the various combinations.

  • 2
    Thank you! That looks better than what I had, and I appreciate the explanation. One thing that was fixed by what I had, but not by your lines, was that up/down arrows didn't work in the Command-T plugin as described here: superuser.com/questions/237751/… I just added map <Esc>[B <Down> from one of the answers. Seems the reason there is some bad assumptions made by the plugin itself.
    – Henrik N
    Mar 18, 2012 at 20:51
  • Just to be clear, your solution plus map <Esc>[B <Down>from that other thread means everything now works fine.
    – Henrik N
    Mar 18, 2012 at 21:02
  • @HenrikN Could you please clarify what map <Esc>[B <Down> does? I don't see any difference by adding it to my .vimrc file.
    – Tropilio
    Apr 10, 2019 at 12:01
  • @Francesco Boccardo: If you follow the link in my previous comment, and then follow the link again from there, you get to superuser.com/a/215181 which seems to explain it in excruciating detail :)
    – Henrik N
    Apr 10, 2019 at 18:54
  • @HenrikN Thanks. So it is probably an OSX related issue, or maybe it's been resolved in these 7 years, because pressing command (control?) + r doesn't mess up the arrow keys in vim in tmux for me (I am on Linux).
    – Tropilio
    Apr 11, 2019 at 7:39

As explained here, disable Background Color Erase (BCE) by clearing the t_ut terminal option (run :set t_ut= in Vim and then press Control+L to refresh the terminal's display) so that color schemes work properly when Vim is used inside tmux and GNU screen.

This way, you can keep your TERM value as xterm-256color for proper key detection while also getting proper Vim color scheme rendering too! :-)

  • 1
    Beautiful! Great detective work.
    – Henrik N
    Mar 8, 2013 at 19:58
  • 2
    This is what I changed exactly: github.com/henrik/dotfiles/commit/… Colors and modifier keys seem to work well both outside and inside tmux.
    – Henrik N
    Mar 8, 2013 at 19:59
  • The docs says: "The TERM environment variable must be set to ‘screen’ or ‘tmux’ for all programs running inside tmux. New windows will automatically have ‘TERM=screen’ added to their environment, but care must be taken not to reset this in shell start-up files or by the -e option." And: " For tmux to work correctly, this must be set to ‘screen’, ‘tmux’ or a derivative of them."
    – x-yuri
    Jan 7, 2022 at 22:24

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