For a long time I've used tmux for split horizontal and vertical windows

I found the default key mappings cumbersome and so I remapped split vertical and split horizontal from being the quotes (") and percentage (%) keys to being the - and | keys.

I remapped these to "|" and "-" which I find both easier to remember and easier to key (less hand stretching!)

However with the latest version of tmux this mapping is not longer recognized.
I get errors about split-window: command not found

I can still use the original keys - " and % - without a problem

This is the mapping I've used previously:

bind | split-window -h -c '#{pane_current_path}'  # Split panes horizontal
bind - split-window -v -c '#{pane_current_path}'  # Split panes vertically

More Details:

tmux source ~/.tmuux.conf


$ tmux source ~/.tmux.conf
tmux source ~/.tmux.conf
unknown key:  split-window
history -a

Update: using quotes around the mapping key works.

  • Are the keybindings listed if you run list-keys? I'm using: bind "'" split-window -h and: bind "-" split-window -v, which works fine. Jul 27, 2020 at 10:39
  • I don't see them as mappings When I do your command I get "split-window: command not found". Maybe my tmux version? Jul 27, 2020 at 11:05
  • I am using tmux 3.0a and i recently upgraded Ubuntu from 19 to 20 (current version). Jul 27, 2020 at 11:10
  • 1
    please post as answer Jul 27, 2020 at 12:01
  • 1
    Thanks - and good luck! Jul 27, 2020 at 12:17

1 Answer 1


After reviewing your .tmux.conf it would appear that the error is binding the \ key without quotes. The correct binding would then be:

bind '\' split-window -h

The same goes if you want to use the quote keys, in which case you would have to use either:

bind '"' split-window -h


bind "'" split-window -h

Next, you could try adding the second parameter -c '#{pane_current_path}' and see if it still works.

  • This is super helpful as I was trying without the quote like bind \ split-window -h and obviously, it was not working.
    – Arefe
    Jul 16, 2021 at 0:29

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