/2009/12/30/sync-your-music-collection-to-your-android-device/

Sync your music collection to your Android device

Motorola DROID

Use rsync to keep your music collection in sync with your Android device:

rsync --delete --force -azrpogtP /<PATH TO MUSIC> /<DROID MOUNT POINT>

EDIT: It's easier and more consistent to use doubleTwist.

December 30, 2009