Checks RSS feed for new content and sends push notification via ntfy.sh

iphoneblog-update-notifier.sh

#!/usr/bin/env bash
set -euo pipefail

# the rss feed url to check
FEED_URL="https://www.iphoneblog.de/feed/"

# temporary state file to compare
STATE_FILE="/tmp/rss-top-item.id"
mkdir -p "$(dirname "$STATE_FILE")"

# download rss feed content
feed="$(curl -fsSL "$FEED_URL")"

# extract title, link and guid of latest item on feed
title="$(
  printf '%s' "$feed" |
    xmllint --xpath 'string((//item)[1]/title)' -
)"

link="$(
  printf '%s' "$feed" |
    xmllint --xpath 'string((//item)[1]/link)' -
)"

guid="$(
  printf '%s' "$feed" |
    xmllint --xpath 'string((//item)[1]/guid)' -
)"

# if guid is missing: use link or title
item_id="${guid:-${link:-$title}}"

if [[ -z "$item_id" ]]; then
  echo "Konnte kein RSS-Item auslesen." >&2
  exit 1
fi

if [[ ! -f "$STATE_FILE" ]]; then
  printf '%s\n' "$item_id" > "$STATE_FILE"
  echo "Initialer Stand gespeichert."
  exit 0
fi

old_id="$(cat "$STATE_FILE")"

if [[ "$item_id" != "$old_id" ]]; then
  printf '%s\n' "$item_id" > "$STATE_FILE"

  echo "Neues Item gefunden:"
  echo "Titel: $title"
  echo "Link:  $link"
  echo "Sende Push Benachrichtigung mit Link und Vorschaubild."

  content="$(
    printf '%s' "$feed" |
      xmllint --xpath 'string((//item)[1]/*[local-name()="encoded"])' -
  )"

  image_url="$(
    printf '%s\n' "$content" |
      sed -n 's/.*<img[^>]* src="\([^"]*\)".*/\1/p' |
      head -n 1
  )"

  # send push notification via ntfy.sh
  result=$(/usr/bin/curl -s -X POST -H "Title: Neuer iPhoneblog Artikel" -H "Click: $link" -H "Tags: memo" -H "Attach: $image_url" -d "$title" https://ntfy.sh/******) 
else
  echo "Kein neues Item."
fi