core/cups/cups.install

add_daemon() {
  local checkdmn=$(grep '^DAEMONS' /etc/rc.conf | grep cups)

  if [ -z "${checkdmn}" ]; then
    sed -i '/^DAEMONS/{s/)$/ cups)/}' /etc/rc.conf
  fi
}

add_group() {
  # Create the "lpadmin" group, if needed
  if ! getent group lpadmin 2> /dev/null; then
    groupadd --system lpadmin
  fi

  # Add all the users in the "lp" group to "lpadmin" (expect for "daemon")
  for user in $(getent group lp | cut -d ':' -f 4 | tr ',' ' '); do
    [ "${user}" != "daemon" ] && gpasswd -a "${user}" lpadmin > /dev/null
  done
}

post_install() {
  xdg-icon-resource forceupdate --theme hicolor 2> /dev/null
  echo ">> If you use an HTTPS connection to CUPS, the first time you access"
  echo ">> the interface it may take a very long time before the site comes up."
  echo ">> This is because the first request triggers the generation of the CUPS"
  echo ">> SSL certificates which can be a very time-consuming job."
  add_group
  add_daemon
  /etc/rc.d/cups restart
}

post_upgrade() {
  xdg-icon-resource forceupdate --theme hicolor 2> /dev/null

  # If the "lp" user group is still present, and the user has not changed the cupsd.conf
  # from the old default "SystemGroup sys root" setting, let's replace that line, so that
  # it will also allow for the "lp" user group to administrate CUPS.
  # Without this, non-root users will see the Printers KCM silently hang (the CUPS server
  # will deny access).

  local cupsd=etc/cups/cupsd.conf

  if ( getent group lp && grep '^SystemGroup sys root$' "${cupsd}") &>/dev/null; then
    echo "[NOTICE] The CUPS configuration is being automatically tweaked to allow all users belonging to the \"lp\" group to administrate the server."
    sed -i 's/^SystemGroup sys root$/SystemGroup sys root lpadmin/g' "${cupsd}"
  fi

  add_group
  add_daemon
  /etc/rc.d/cups restart
}

pre_remove() {
  /etc/rc.d/cups stop
}

post_remove() {
  xdg-icon-resource forceupdate --theme hicolor 2> /dev/null
  sed -i '/^DAEMONS/{s/ cups)$/)/}' /etc/rc.conf
}