Fd binds an http server to the
provided file descriptor and starts
it asynchronously. If the server ever
stops running, the error returned
from http.Serve is passed to errorln.
Path creates a unix socket at path and listens on it
for debug connections. The ok() function is used to
filter connections based on the credentials of the
process on the other end of the connection.
See also Fd, which uses a local file descriptor
rather than a local unix socket path.