core/systemd/systemd.install

#!/bin/sh

checkgroups() {
  if ! getent group lock >/dev/null; then
    groupadd -g 54 lock
  fi
}

sd_booted() {
  [ -e sys/fs/cgroups/systemd ]
}

post_install() {
  checkgroups

  if [ ! -f etc/machine-id ]; then
    systemd-machine-id-setup
  fi

  echo "systemd has been installed to /bin/systemd. Please ensure you append"
  echo "init=/bin/systemd to your kernel command line in your bootloader."
}

post_upgrade() {
  checkgroups

  if [ ! -f etc/machine-id ]; then
    systemd-machine-id-setup
  fi

  if sd_booted; then
    systemctl daemon-reexec >/dev/null
  fi

  newpkgver=${1%-*}
  oldpkgver=${2%-*}

  # catch v31 need for restarting systemd-logind.service
  if [ "$newpkgver" -ge 31 ] && [ "$oldpkgver" -lt 31 ]; then
    # but only if systemd is running
    if sd_booted; then
      systemctl try-restart systemd-logind.service
    fi
  fi
}

post_remove() {
  if getent group lock >/dev/null; then
    groupdel lock
  fi
}