How to reorganize a tmux layout?
Short answer
tmux select-layout tiled # apply the tiled (grid) layout now
tmux select-layout main-vertical # one large pane left, the rest stacked rightprefix Space cycles through the five preset layouts; select-layout <name> jumps straight to
one. After pulling several panes into a window and ending up with a lopsided split,
select-layout tiled re-tiles everything into an even grid in one step.
Details
The five presets are even-horizontal (equal columns), even-vertical (equal rows),
main-horizontal (one large pane on top, the rest in a row below), main-vertical (one large
pane on the left, the rest in a column on the right), and tiled (an even grid). prefix Space
runs next-layout and walks through them in that order, wrapping back to the start.
select-layout <name> skips the cycling and applies a named layout directly, which is the one
you actually want in a script or after a reshuffle. Each layout also has a direct key binding:
prefix M-1 even-horizontal, M-2 even-vertical, M-3 main-horizontal, M-4 main-vertical,
M-5 tiled (M- is Alt).
A layout is applied once: tmux computes the pane sizes at that moment, then lets you resize
freely afterwards. Splitting or closing a pane does not re-apply it. So the usual move after
rearranging panes is to run select-layout tiled (or your layout of choice) again to clean up.
Verified on tmux 3.2a.