Cobbled together logic for insert a new item in the mp3 feed.

.gitignore

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+*.swp
+*out.xml

append.py

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+import sys
+import feedparser
+from urllib2 import HTTPError, URLError
+import logging
+
+def __fetch_feed(url):
+    try:
+        feed = feedparser.parse(url)
+
+        return feed.entries[0]
+    except HTTPError, e:
+        logging.error('Failed with HTTP status code %d' % e.code)
+        return None
+    except URLError, e:
+        logging.error('Failed to connect with network.')
+        logging.debug('Network failure reason, %s.' % e.reason)
+        return None
+
+def __append_mp3(entry):
+    latest = __fetch_feed('cmdln_mp3_in.xml')
+    if entry.title.find(latest.title) != -1:
+        logging.info('Up to date.')
+        return
+    f = open('cmdln_mp3_in.xml')
+    o = open('cmdln_mp3_out.xml', 'w')
+    first = False
+    try:
+        for line in f:
+            if line.find('<item>') != -1 and not first:
+                logging.info('Insert new item.')
+                first = True
+            else:
+                logging.info('Preserve existing item.')
+            o.write(line)
+    finally:
+        f.close()
+
+def main():
+    logging.basicConfig(level=logging.INFO,
+            format='%(message)s')
+    entry = __fetch_feed('http://thecommandline.net/category/podcast/feed/')
+    if entry is None:
+        logging.error('Failed to fetch feed.')
+        sys.exit(1)
+
+    __append_mp3(entry)
+
+    print entry.title
+
+if __name__ == "__main__":
+    main()