bitcoin/bitcoin — pull request #714 by luke-jr (2011-12-19 19:34:50+00:00)
Title: Execute a command when best block changes (-blknotify=<cmd>)

This supercedes pull request #555 in a more flexible manner, including Windows support.

To get the same behaviour as: -blknotifypidfile=/path/to/some.pid
Now you do: -blknotify='kill -USR1 $(