The XO contacts OLPC on average once a day in order to see if there is a new build which it should be running. Each XO can be subscribed to one of a number of "update streams":
- none - never update me.
- stable - latest stable build
- testing - release candidates or stable upgrade testing
- joyride - not yet implemented, but will someday give you the latest joyride build automatically.
See https://activation.laptop.org/streams/ for the full list.
The stream an XO is subscribed to is determined as follows:
- If there is a file named /security/update-stream containing a stream name, use it.
- Otherwise, if there is a file named /etc/olpc-update/update-stream with a stream name, use this. (This is used in joyride builds to ensure the joyride machines are by default subscribed to joyride, not stable.)
- Otherwise, if the laptop belongs to an 'update group' in OLPC's database, and the update group names a default stream, use it. (This allows us to remotely upgrade XOs in school deployments.)
- Otherwise, use the default update stream specified by the server, which is currently 'stable'.
 Automatic update prevention
echo none > /security/update-stream
then press the Enter key.