Ever wondered how you would send the clear command to each pane, in each window, in each session in tmux, or how you would do source your shell config file in each after each tweak?

Here are few excerpts from my .tmux.conf that allow doing just that.

Send command to all panes in all sessions #

Thanks to the tip in comments from Bob Fleming, I learned that tmux has a -a switch for the list-panes command.

From man tmux,

list-panes [-as] [-F format] [-t target]
              (alias: lsp)
        If -a is given, target is ignored and all panes on the server
        are listed.  If -s is given, target is a session (or the
        current session).  If neither is given, target is a window (or
        the current window).  For the meaning of the -F flag, see the
        FORMATS section.

With that knowledge, the older version of the E binding now reduces to,

# Send the same command to all panes/windows/sessions
bind E command-prompt -p "Command:" \
       "run \"tmux list-panes -a -F '##{session_name}:##{window_index}.##{pane_index}' \
              | xargs -I PANE tmux send-keys -t PANE '%1' Enter\""

Usage #

• Type the following binding in any tmux pane: C-z E¹
• Enter a command that you would want to send to all the panes, like source ~/.alias; clear (this is entered in the tmux command prompt).
• That will source the ~/.alias in all panes, and then clear the terminals as well.

About the ## #

.. because otherwise, tmux run-shell command will replace the unescaped #{session_name}, #{window_index} and #{pane_index} with their current values before executing the command.

With the hashes escaped, those variables will be evaluated at run time.

But if you were to type the above command directly in the terminal, without the run-shell command wrapper, you would use only single #:

tmux list-panes -s -F "#{session_name}:#{window_index}.#{pane_index}"

Send command to all panes in current session #

The list-panes command has another useful switch: -s, which takes an optional argument, a session name. If that argument is not supplied, it takes the current session name by default.

Below C-e binding is used to send a command to all panes, in all windows, but only in the current session.

bind C-e command-prompt -p "Command:" \
         "run \"tmux list-panes -s -F '##{session_name}:##{window_index}.##{pane_index}' \
                | xargs -I PANE tmux send-keys -t PANE '%1' Enter\""

Older version (circa 2014) #

# Send the same command to all panes/windows/sessions
bind E command-prompt -p "Command:" \
       "run \"tmux list-sessions                                           -F '##{session_name}' \
              | xargs -I SESS          tmux list-windows  -t SESS          -F 'SESS:##{window_index}' \
              | xargs -I SESS_WIN      tmux list-panes    -t SESS_WIN      -F 'SESS_WIN.##{pane_index}' \
              | xargs -I SESS_WIN_PANE tmux send-keys     -t SESS_WIN_PANE '%1' Enter\""