Screens that switch by themselves (extras/kanshi.sh)

SYNOPSIS

wrenctl install kanshi                         install it
wrenctl remove kanshi                          remove it
wrenctl manual kanshi                          print the manual steps below

swaymsg -t get_outputs                         your screens' names, for the config
~/.config/kanshi/config                        which screens are on, when

kanshi changes which screens are on when you plug a monitor in or out. As installed: the laptop alone uses its own screen, and with a monitor plugged in only the monitor is on, lid open or closed. A setup that matches neither (two monitors, a desktop computer) is left alone, and sway keeps every screen on. The file is yours: Wren Linux writes it only when there is none, and never replaces it.

LIMITS

• It knows the laptop's screen as eDP-1, as most laptops (the ThinkPad T490 among them) name it. Another name: change it in the file.
• A monitor that is plugged in but shows nothing still turns the laptop's screen off: unplug it to get the laptop's screen back.
• It has nothing to do with security or privacy.

MANUAL INSTALL

# kanshi, from Debian
sudo apt install --no-install-recommends kanshi
# Its config: the laptop alone on its own screen, a monitor plugged in alone
mkdir -p ~/.config/kanshi
printf '%s\n' 'profile laptop {' '    output eDP-1 enable' '}' 'profile monitor {' '    output eDP-1 disable' '    output * enable' '}' >~/.config/kanshi/config
# sway starts it at every login, and again at every reload (a reload turns every
# screen on, and kanshi then puts its profile back)
echo 'exec_always sh -c '\''pkill -x -u "$(id -u)" kanshi; exec kanshi'\''' >~/.config/sway/config.d/kanshi.conf

To undo:

# sway's line, kanshi itself; your config stays
rm ~/.config/sway/config.d/kanshi.conf
pkill -x kanshi
sudo apt purge kanshi