How do I rename a pane in tmux?

Renaming a window

Ctrl-b ,

where Ctrl-b is the default prefix key.

Alternatively, run:

tmux rename-window <new name>

Or type Ctrl-b : rename-window <new name>.

Renaming a pane

In newer versions you can rename pane using:

tmux select-pane -T <title>

Or type Ctrl-b : select-pane -T <pane_name>.

Also, I have set -g pane-border-status top and set -g pane-border-format " [ ###P #T ] " in .tmux.conf.