TMUX: After split-window, how to know the new pane id

tmux

It seems like a simple enough procedure that I'm trying to accomplish, yet I've searched to no avail. I would like to create a key binding which does a split-window and then send-keys to the newly-created pane; however I need the pane id to use with the send-keys command. The catch is that I WILL NOT know how many panes are currently open in the window; thus I know of no way for the code running in the original pane to deduce what the new pane index will be. Is there any way to find out this new index or id (either one can be used as a target)?

Thanks.

Best Answer

You are over-thinking your problem. When you do split-window the new pane becomes the current target for send-keys. You should not be calling tmux in the binding as you are already in tmux. Try

bind-key s split-window \; send-keys "pwd" Enter

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Get pane # of each pane in a window from a script

tmux (since v1.5) provides TMUX_PANE in the environment of the process it launches for a pane; each new pane gets a server-unique value. So, assuming that TMUX_PANE is available in your environment, then this should do what I think you want:

tmux display -pt "${TMUX_PANE:?}" '#{pane_index}'

The ${…:?} syntax in a Bourne-like shell prevents the expansion of missing or empty parameters. In this case, an empty expansion would fall back to the default of using “the currently active pane”, which is usually—but not always—the same as “this pane” (they will likely differ if the command’s tty is not the one that tmux started; e.g. because of using script or expect, et cetera).

Best Answer

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Get pane # of each pane in a window from a script

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