Command Specific Options
If --terse is specified on a getvcp command, output is in a format this is easily machine readable, to facilitate use in scripts. 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. Normally not reported for multi-feature getvcp requests, but see --show-unsupported If reported, output takes the form:
VCP feature-code ERR
VCP 84 ERR
If querying a single feature, getvcp reports an error if the feature is unsupported or some other error occurs. If querying a feature subset, e.g. COLOR, output for invalid features is suppressd. The --show-unsupported option forces error messages in all cases.
Commands setvcp, loadvcp
The underlying DDC operation used by setvcp writes the command specifying a new VCP value to the I2C bus. The status code from this operation simply indicates whether the write was successful. It does not indicate whether the display successfully received and processed the command. There have been occasional reports in the field of cases where the setvcp command appeared to succeed, but the new value was not set. Therefore setvcp and loadvcp by default read the feature value to verify that the value in the monitor has actually changed.
As this facility causes a minor increase in processing time and addresses a rare condition, it can be disabled using the --noverify option.
Display informational messages regarding verification.