Syntax: getvcp <monitor selection options> <other options> <feature-code-or-group>
Monitor selection options are detailed here.
Feature code/group specification is detailed here.
If a feature group has been specified, there is normally no message if a feature is unsupported. This rule is not absolute. For some feature-groups it is appropriate to always report that a feature is unsupported. This is also affected by the --show-unsupported option described below.
Option: --terse, --brief
If --terse is specified on a getvcp command, output is in a format this is easily machine readable. This format is also used by vcpinfo.
The format depends on the feature type. In keeping with ddcutil practice, VCP feature codes are shown without a leading hex indicator even though they are hexidecimal values.
For a continuous VCP feature, both the current value (in decimal) and maximum value (in decimal) are shown. Output takes the form:
VCP feature-code C cur-value-decimal max-value-decimal
VCP 10 C 50 100
For a simple non-continuous VCP feature, i.e. one for which only the SL response byte is significant, the value is reported in hex. Output takes the form:
VCP feature-code SNC hex-value
VCP 60 SNC x03
Complex non-continuous VCP features are ones for which more then 1 response byte is significant. In that case all 4 bytes are reported in hex. Output takes the form:
VCP feature-code CNC mh-hex ml-hex sh-hex sl-hex
VCP DF CND xff xff x02 x00
Table VCP features report the value as hexidecimal string. Output takes the form:
VCP feature-code T hex-string
VCP 73 T x01020304
Finally, if a feature is not supported or some other error occurs, this may be reported or there may simply be no output. It is always reported for single feature getvcp requests. It is normally not reported if the request specifies a feature group, which defines a set of features. but see --show-unsupported. If reported, output takes the form:
VCP feature-code ERR
VCP 84 ERR
The internal representation (bytes MH, ML, SH, SL) is shown. Unsupported features are always reported.
If querying a single feature, getvcp reports an error if the feature is unsupported or some other error occurs. If querying a feature group, e.g. COLOR, output for invalid features is suppressd unless --verbose is specified. The --show-unsupported option forces error messages in all cases.