A script to automatically do things when it detects a dock/undock 'event'. Only works when polling the script continuously

systemd-logind-docked-events-min.sh

# - Get the 'docked' state from the systemd-logind D-Bus interface
#   See: https://www.freedesktop.org/software/systemd/man/org.freedesktop.login1.html
# - Get the 'value' from the dbus-send command.
#   The reply is in the format of `   variant       boolean <value>`
#   Where <value> is either `true` or `false`
_is_docked=$(dbus-send \
  --system \
  --print-reply=literal \
  --reply-timeout=120000 \
  --type=method_call \
  --dest='org.freedesktop.login1' \
  '/org/freedesktop/login1' \
  org.freedesktop.DBus.Properties.Get \
  string:'org.freedesktop.login1.Manager' string:'Docked' \
  | awk '{print $3}')


if [[ "${_is_docked}" == "true" ]]; then
  # Laptop (https://emojipedia.org/laptop/) + Monitor (https://emojipedia.org/desktop-computer/ + Variant selector 16 https://emojipedia.org/emoji/%EF%B8%8F/)
  printf '\xF0\x9F\x92\xBB\xF0\x9F\x96\xA5\xEF\xB8\x8F'  
  dconf write /org/gnome/desktop/interface/text-scaling-factor 1.00
else 
  # Laptop (https://emojipedia.org/laptop/)
  printf '\xF0\x9F\x92\xBB' # https://emojipedia.org/laptop/
  dconf write /org/gnome/desktop/interface/text-scaling-factor 1.25
fi

systemd-logind-docked-events.sh

#!/usr/bin/env bash
set -o errexit   # abort on nonzero exitstatus
set -o nounset   # abort on unbound variable
set -o pipefail  # don't hide errors within pipes

function docked() {
  # Set the scaling factor to the default value
  dconf write /org/gnome/desktop/interface/text-scaling-factor 1.00
}

function undocked() {
  # Set the scaling factor to accessibility mode 'large-text'
  dconf write /org/gnome/desktop/interface/text-scaling-factor 1.25
}

# - Get the 'docked' state from the systemd-logind D-Bus interface
#   See: https://www.freedesktop.org/software/systemd/man/org.freedesktop.login1.html
# - Get the 'value' from the dbus-send command.
#   The reply is in the format of `   variant       boolean <value>`
#   Where <value> is either `true` or `false`
function is_docked() {
  dbus-send \
    --system \
    --print-reply=literal \
    --reply-timeout=120000 \
    --type=method_call \
    --dest='org.freedesktop.login1' \
    '/org/freedesktop/login1' \
    org.freedesktop.DBus.Properties.Get \
    string:'org.freedesktop.login1.Manager' string:'Docked' \
    | awk '{print $3}'
}

function was_docked() {
  local was_docked_filename="/run/user/${UID}/was-docked.systemd-logind-docked-events"
  if [ ! -f "${was_docked_filename}" ]; then
    touch "${was_docked_filename}"
  fi
  cat "${was_docked_filename}"
}

function set_dock_state() {
  local was_docked_filename="/run/user/${UID}/was-docked.systemd-logind-docked-events"
  echo "${1}" > "${was_docked_filename}"
}

function main() {
  if [[ "$(is_docked)" == "true" ]]; then
    # Docked
    echo "💻🖥️"
  else
    # Not docked
    echo "💻"
  fi

  if [[ "$(is_docked)" != "$(was_docked)" ]]; then
    if [[ "$(is_docked)" == "true" ]]; then
      docked
    else
      undocked
    fi
    set_dock_state "$(is_docked)"
  fi
}

main