Alexander Dupuy

This is a great idea, and you can even use the contextlib implementation in 3.2+ (or contextlib2 for Python 2.7): http://stackoverflow.com/a/9213668/18829

I just use the "removes=" option for Ansible "command" module to selectively run the reboot - much simpler, and no handler needed.

tasks:
- name: Reboot system if required
  command: shutdown -r now 'Rebooting to complete system upgrade'
            removes=/var/run/reboot-required

Actually, the non /usr/bin/env form doesn't work at all under MacOS X, because Darwin requires that the shebang interpreter be an executable binary program (not another shebang script) and all the Ansible commands are actually Python scripts. See http://stackoverflow.com/questions/9988125/shebang-pointing-to-script-also-having-shebang-is-effectively-ignored