Command Overview

ddcutil is a command line program. (A GUI user interface is planned.) ddcutil implements the following subcommands:

Subcommand Function
detect report monitors detected
capabilities report a monitor's capabilities string
vcpinfo (feature-code-or-group) list VCP features codes that ddcutil knows how to interpret
getvcp feature-code-or-group report a single VCP feature value, or a group of values
setvcp feature-code new-value set a single VCP feature value
dumpvcp filename save color related VCP feature values to a file
loadvcp filename restore color related VCP feature values from a file
environment explore the ddcutil installation environment (other than USB)
usbenv explore USB aspects of the ddcutil installation environment
probe explore the capabilities string and probe the features of a single monitor
interrogate collect maximal information for problem diagnosis
chkusbmon /dev/hiddevN used by udev rules to test if a USB device represents a monitor

There is an extensive set of options for tailoring ddcutil operation. Some are described in this documentation. For a full list of options and detailed documentation for each command, use the --help option or see the man page:

$ ddcutil --help
$ man 1 ddcutil

Monitor Selection

If more than one monitor is attached, the desired monitor can be specified using any of the following options:

--display <display number>
--bus <i2c bus number>
--adl <iAdapterNumber>.<iDisplayNumber>
--usb <usb bus number>.<usb device number>
--edid <256 character hex string>
--mfg <mfg code> --model <model name> and/or --sn <serial number>


  • Monitors under control of AMD's proprietary driver (fglrx) are selected by adapter number and display number. These numbers are specified on the --adl option separated by a period, e.g. "--adl 1.0"
  • Any combination of manufacturer code, model name and serial number can be used together to identify a monitor. The first monitor to satisfy all the specified criteria is selected. (This behavior differs from releases prior to 0.7 where model name and serial number had to be specified together.)

To see a list of all attached monitors and their associated identifiers:

$ ddcutil detect