You may also use a command line tool like xmlstarlet (together with HTML tidy):
# version 1curl -s http://stackoverflow.com/questions/2441954/how-to-find-out-the-exact-rss-xml-path-of-a-website | tidy -q -c -wrap 0 -numeric -asxml -utf8 --merge-divs yes --merge-spans yes 2>/dev/null |xmlstarlet sel -T -t -m "//*[local-name()='link']" --if "@type='application/atom+xml' or @type='application/rss+xml'" -m "@href" -v '.' -n# version 2curl -s http://stackoverflow.com/questions/2441954/how-to-find-out-the-exact-rss-xml-path-of-a-website | tidy -q -c -wrap 0 -numeric -asxml -utf8 --merge-divs yes --merge-spans yes 2>/dev/null |xmlstarlet sel -N x="http://www.w3.org/1999/xhtml" -T -t -m "//x:link[@type='application/atom+xml' or @type='application/rss+xml']" -v "@href" -n