The music store is coming soon to Ubuntu 10.04. Here are some answers to questions that many users have been asking.
Ubuntu One Music Store
The Ubuntu One Music Store is now in public beta. Please be aware that things will break. We want your feedback when this happens so please review the FAQ below for testing recommendations and answers to popular questions. Also please review this blog post for more testing details.
If you are already running Lucid, ensure that you have the latest updates and start Rhythmbox to begin testing.
The Ubuntu One Team
Q: Where should testers file bugs?
Beta testers should report bugs against the Rhythmbox Ubuntu One Music Store project. In order for the team to capture the most information about your issue, please file a bug by opening a terminal and typing the following.
Q: How do I get the store to work? It doesn't seem to be working.
Make sure that the Ubuntu One software on your desktop is connected. Choose "Ubuntu One..." from the Me Menu (or choose System > Preferences > Ubuntu One). Choose the "Devices" tab and click "Connect".
During the beta-test you may want to connect your machine to Ubuntu One before using the Music Store.
You may find that this doesn't work during the beta-testing period. There is a command-line fallback. In a Terminal (Applications > Accessories > Terminal), run u1sdtool -c (written with the number 1) to connect your machine to Ubuntu One. You can then run u1sdtool -s to show the status of your Ubuntu One connection: on first connecting there will be a "local scan", then a "server rescan", and then it should settle into a state that looks like:
State: QUEUE_MANAGER connection: With User With Network description: processing queues is_connected: True is_error: False is_online: True queues: IDLE
with is_connected and is_online being True.
Please see the Music Store section of the Ubuntu One FAQs