Apple - how to quickly reboot from OSX to Windows and back

Note: This does not work on systems with System Integrity Protection enabled

Write a shell script that does this

#!/bin/sh
# tell OSX to change the boot disk 
# nextonly just for the next time - without the default would be Windows
/usr/sbin/bless -mount /Volumes/BOOTCAMP --setBoot  --nextonly  
# reboot
/sbin/shutdown -r now

This can be called from a terminal window

sudo bootcamp

The use Automator to call this via an apple script and save as an application

on run {input, parameters}

    do shell script "/Users/mark/bin/bootcamp" with administrator privileges

    return input
end run

Another way to get from OS X to Windows quickly is to use Bootchamp, which adds a menu bar item like this:

For my Windows-booting needs Bootchamp has worked well.

(I learned about it from a similar question on Super User I once asked.)

Hold ⌥ while booting, you'll get a prompt to choose which OS / drive you want to boot from!