Mirror a tmux session in two terminals.

tmuxshow

#!/bin/sh

# SPDX-FileCopyrightText: 2018 Kirill Elagin <https://kir.elagin.me/>
# SPDX-License-Identifier: MPL-2.0

###
#
# Mirror a tmux session in two terminals.
#
# This script is ideal for all kinds of demonstrations, lectures, talks, etc.
# The idea is that you connect a projector (or a large display) as a second
# screen to your laptop, open two terminal windows – one on your laptop’s screen,
# other on the projector, and then you “tie” them together with a tmux session.
#
# Use:
#
#   * Download this script and put it on your $PATH
#     (or use its full path when invoking it)
#
#   * Open two terminal windows.
#
#   * Run `tmuxshow` in one window. Then run `tmuxshow` in the other.
#
#   * All set! Now both terminals will always show the same content.
#
# Dependencies:
#
#   * tmux
#
# e.g. `nix-shell -p tmux
#
# https://gist.github.com/kirelagin/bbb182e6102116c3d984fd630e24abe4
###


command -v &> /dev/null || { echo "Need tmux"; exit 1; }

read -r -d '' initCmd << EOM
set default-command /bin/zsh;
set default-terminal screen-256color;
set status off;
set escape-time 0;
set bell-action current;

set renumber-windows on;
new-window;
kill-window -a;
EOM

tmux -f /dev/null new-session -s tmuxshow \; $initCmd 2> /dev/null || tmux -f /dev/null attach-session -t tmuxshow