How to convert 2 horizontal panes to vertical panes in tmux

Up, Down, Left, and Right (select-pane bindings; and Control- and Meta- of the same keys for resize-pane) are “repeatable” bindings by default (made via bind-key -r). After typing the prefix key and any single repeatable key, you can type any other repeatable key (without having to type the prefix again) within the number of milliseconds specified via the repeat-time session option (the default is 500ms).

You can examine the current value of repeat-time with these shell commands:

tmux show-options -g | grep \^repeat-time     # global
tmux show-options    | grep \^repeat-time     # this session

If you want to disable the repeat for the current session, then type your prefix, a colon, and enter this command:

set-option repeat-time 0

Or, you might be able to find a comfortable non-zero value. If you really do have a value of around 2000 (i.e. 2s), then I would guess that it is being set in /etc/tmux.conf.

If you want to disable repetition (or change the timeout) for all your sessions, then set the global value with this command:

set-option -g repeat-time 0

If you have set a per-session value, you will need to unset it before the global value will take effect in that session (set-option -u repeat-time). You may like to set the global value via your .tmux.conf if you prefer to leave it off “permanently”.

If you only have problems with Up, you could rebind it without -r:

bind-key Up select-pane -U

I suggest resizing multiple panes with one of the five tmux presets:

C-b M-1             # vertical split, all panes same width
C-b M-2             # horizontal split, all panes same height
C-b M-3             # horizontal split, main pane on top,
                      other panes on bottom, vertically split, all same width
C-b M-4             # vertical split, main pane left,
                      other panes right, horizontally split, all same height
C-b M-5             # tile, new panes on bottom, same height before same width

M denotes the meta key, usually bound to ALT.

On Macs the meta key is usually Esc, as mentioned in the comment below.

See the tmux manpage for more information.