15.3 Device Availability Per Session

For every Sun Ray Client or Oracle Virtual Desktop Client session on a Sun Ray server, Sun Ray Software creates a subdirectory under /tmp/SUNWut/units. The subdirectory matches the name of the client’s identifier, or CID. A Sun Ray Client’s CID is named IEEE802.MACID, where MACID is the Sun Ray Client’s MAC Address. An Oracle Virtual Desktop Client’s CID is named MD5.CLIENTID where CLIENTID is the hexadecimal representation of each Oracle Virtual Desktop Client profile’s MD5 hash key. For more information on the difference between Sun Ray and Oracle Virtual Desktop Client CIDs, see Section 13.1.1, “Client ID Differences Between Oracle Virtual Desktop Clients and Sun Ray Clients”.

Each session has a $UTDEVROOT environment variable, which is an alias to that session’s current CID subdirectory. $UTDEVROOT is a dynamic variable that updates whenever the user hotdesks between devices. If the $UTDEVROOT variable is not available, such as in kiosk mode, you can always display the client ID as described in Section, “How to Display Client ID Information”.

The following example shows how to find the CID subdirectory for a Sun Ray Client through the $UTDEVROOT variable (using bash shell):

# cd -P $UTDEVROOT     
# pwd

The subdirectory for each client contains dev and devices directories. The Sun Ray dev directory contains a representation of the logical topology of the devices connected to the client. The devices directory contains a representation of the physical topology of some of the devices connected to the client.

When accessing or referencing devices connected to the current client, always use the dev directory, because the logical device gets updated whenever a user moves from client to client and the path to the device does not contain any special characters that may need special handling in a script.


Sun Ray Software does not create device nodes for every USB device. Some USB device drivers export their device interfaces through other mechanisms than a traditional UNIX device node.