File: /var/lib/dpkg/info/nginx.postinst
#!/bin/sh
set -e
case "$1" in
  abort-upgrade|abort-remove|abort-deconfigure|configure)
    ;;
  triggered)
    if invoke-rc.d --quiet nginx status >/dev/null; then
      echo "Triggering nginx reload ..."
      invoke-rc.d nginx reload || true
    fi
    exit 0
    ;;
  *)
    echo "postinst called with unknown argument \`$1'" >&2
    exit 1
    ;;
esac
if invoke-rc.d --quiet nginx status >/dev/null; then
  invoke-rc.d nginx upgrade || invoke-rc.d nginx restart
  exit $?
else
  if [ -z "$(ss -nlt 'sport = 80' | grep -v ^State)" ]; then
    invoke-rc.d nginx start || exit $?
  else
    echo "Not attempting to start NGINX, port 80 is already in use."
    exit 0
  fi
fi
exit 0