/bin/bash is a Linuxism. Other operating systems install bash to
different paths. Use /usr/bin/env in shebangs to find bash.
Signed-off-by: Alan Somers <asomers@gmail.com>
Export a diff of an image from a previous snapshot to a file (or stdout).
Import a diff and apply it to an image, and then create the ending
snapshot.
Signed-off-by: Sage Weil <sage@inktank.com>