How to write to NTFS USB drives on Mac OS X

Mac OS X by default can only read from attached USB drives with the NTFS file system. Here are the steps to enable read/write access:

Initial setup (only first time on a new Mac)

1. Install Homebrew (and probably additional XCode tools)
2. In Terminal: brew install caskroom/cask/osxfuse
3. In Terminal: brew install ntfs-3g
4. In Terminal: sudo mkdir -p /Volumes/NTFS

Each time when an NTFS USB drive is connected to the computer

1. List disk partitions: diskutil list
2. Find identifier of the partition with Windows_NTFS type (typically disk2s1 or disk3s1)
3. Unmount found drive: sudo umount /dev/disk2s1
4. Mount the drive with read/write access: sudo ntfs-3g /dev/disk2s1 /Volumes/NTFS -olocal -oallow_other
5. The mounted drive should appear on the desktop, the file system should be mounted at /Volumes/NTFS.

The same steps in a shell script

sudo mkdir -p /Volumes/NTFS

DISK=`diskutil list | grep Windows_NTFS | sed -E "s/.+Windows_NTFS .+ GB +//"`

echo Mounting NTFS disk $DISK

sudo umount /dev/$DISK

sudo ntfs-3g /dev/$DISK /Volumes/NTFS -olocal -oallow_other