til / maximize tmux pane vertically or horizontally

When we have multiple panes open in tmux it can sometimes be hard to focus. I tend to have one main pane for my editor and a smaller horizontal split to the right. The split on the right is used for tests, logs, runners, etc. and usually contains multiple vertical splits.

Zoom in #

We can focus one specific pane using the built-in zoom command ctrl + b, z, where ctrl + b is the default tmux prefix. This is a shorthand for ctrl + b, :, resize-pane -Z.

Temporary maximize #

Sometimes we may want to temporarily maximize a pane vertically or horizontally to have more space to, for instance, view tests or read logs.

What we want to achieve. The split view described above on the left and the same split with one pane maximized vertically on the right.

To do this, we can create custom functions in our .tmux.conf file.

bind -n M-z if -F '#{@layout_save}' \
    {run 'tmux select-layout "#{@layout_save}" ; set -up @layout_save'} \
    {set -Fp @layout_save "#{window_layout}" ; run 'tmux resize-pane -y 100%'}

We start by binding M-z, that’s M for modifier key (cmd on Mac and alt/esc on Linux) plus z. The if-statement checks if the @layout_save variable exists, then:

If it exists, set the layout to that value and remove the variable.
If it does not exist, save the current layout, and resize the current pane to 100% on the y-axis (-y).

This means that pressing cmd + z will toggle the current pane between 100% and its previous layout.

To perform the same action horizontally, copy and paste the function, switch to M-x in the bind, and change -x in resize-pane.

# Use cmd + z (Mac) or alt/esc + z (Linux) to maximize pane size vertically
bind -n M-z if -F '#{@layout_save}' \
    {run 'tmux select-layout "#{@layout_save}" ; set -up @layout_save'} \
    {set -Fp @layout_save "#{window_layout}" ; run 'tmux resize-pane -y 100%'}

# Use cmd + x or alt/esc + x (Linux) to maximize pane size horizontally
bind -n M-x if -F '#{@layout_save}' \
    {run 'tmux select-layout "#{@layout_save}" ; set -up @layout_save'} \
    {set -Fp @layout_save "#{window_layout}" ; run 'tmux resize-pane -x 100%'}

There are some limitations to these commands since they toggle the same variable and don’t take into account when panes are removed. But, it should work for simple use cases.