Example

 $ START:
 $     DEVICE_NAME = F$DEVICE("*0:","DISK","RA60")
 $     IF DEVICE_NAME .EQS. "" THEN EXIT
 $     SHOW SYMBOL DEVICE_NAME
 $     GOTO START

     This command procedure displays the device names of all the
     RA60s on a unit numbered 0.

     Because no stream-id argument is specified, F$DEVICE uses an
     implicit search stream. Each subsequent use of the F$DEVICE
     function uses the same search criteria to return the next
     device name. After the last device name is displayed, the
     F$DEVICE function returns a null string and the procedure
     exits.