Currently reading through this guide to get a good start on understanding tmux. All the other commands described in the guide seem to check out, besides the one in the section Moving on. The command:

C-b C-<arrow key>

does not seem to work on my terminal. All it does is, highlight one half of the vertical divider between my two panes (I wanted two panes split vertically). More specifically, it is what would be left after invoking a C-b % on a vanilla instance of tmux.

Now I had a good look at the .tmux.conf file. The pertinent code is listed below:

# pane resizing 
bind -r H resize-pane -L 2
bind -r J resize-pane -D 2 
bind -r K resize-pane -U 2
bind -r L resize-pane -R 2 

I do not understand the specific syntax that is used in the .conf file, but could someone elaborate on that? I also tried out using C-b L which seems to work, but C-b D just gives the option to detach the session ((as described by the guide) and C-b U and C-b R do not seem to work at all.

My work environment is the raspbian-jessie without the GUI tools and is just the terminal itself (you can imagine why tmux is useful to me).

Please don't hesitate to ask me any other questions about my environment.

2 Answers 2


With that configuration the commands to resize would be ctrl-b H, ctrl-b J, ctrl-b K and ctrl-b L. This is based on the vi movement keys which in turn was based on the ADM-3A (see here)

The manual page describes the bind-key command (of which bind is an alias). Let us consider bind-key -r H resize-pane -L 2. The -r says that the key repeats, so you can type ctrl-b H H H H to do 4 resize steps, the H is the key that is being configured. The resize-pane -L 2 is the command being run. Looking elsewhere in the manual for the resize-pane command one finds that the -L means to make a relative adjustment on the left side and the 2 says to do it by 2 cells (characters).

  • Due to this answer being formatted well and being much more legible, I am going to chose this as the best answer!
    – SDG
    Dec 29, 2016 at 11:37

I have seen this syntax to be invoked in ctrl+b :, and invoking those commands to do the key binding. Assuming these work in conf file without "key-bind" Because you have type capital letters H,J,K,L you have to invoke ^b H This means prefix key (ctrl+b) let go and capital H. Then it will invoke the command "resize-pane -L 2"

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