v4l2ucp reads a description of the controls that the V4L2 device supports from the device, and presents the user with a graphical means for adjusting those controls.
A list of device files can be given on the command line. If no files are given, the program will check the V4L2UCP_DEV environment variable. If it is set, that file will be opened. Finally, it will try to open /dev/video if nothing else was specified. If no devices can be opened, the program will exit.