So I can’t exactly publish this while I’m in the middle of moving my site
to nanoc, but here’s another bash one-liner for
mass-changing an old extension *.old to a new one *.new within a folder.
for file in *.old; do mv "$file" "${file%.*}.new"; done
Pretty useful: I wanted to change from Octopress’s *.markdown extension to
the more typical *.md for my blog posts, and that saved me a few clicks!