This is a small shell script, which generates semi-automagically RSS feeds for
single static HTML pages.

Its most specific requirement is `date -R` for RFC compliant date format, and
`diff -u`.
It uses your text editor from $VISUAL envvar, defaults to vi.

Use it like this:
cd public_html
vim news.html
echo BASE='http://example.org/news.html' > rssgen.conf # only once ofc
./rssgen news.html rss.xml

You might use a Makefile:
rss.xml: news.html
	./rssgen $< $@