betterdisplaycli error handling

[danielskowronski]

betterdisplaycli (CLI) currently handles all errors only by returning Failed. and providing no details or help.

1. The syntax guide is extremely complicated and lacks any usage examples (this is especially tough to follow for DDC commands). Any typo results in Failed. message.
2. help command prints an unformatted markdown file from this registry, which is unreadable and prints some information unrelated to CLI.
3. There's no option to enable verbosity/debug - there's no info other than Failed. to suggest whether user issued a CLI command which does not exist, tried to target a monitor which does not exist, tried to pass illegal parameter value or attempted to issue any command without Better Display actually running.

Given the above, I can't properly file an issue for a problem with my Dell monitor, which I can't control from betterdisplaycli unless DDPM is running, even though Better Display GUI and m1ddc work fine without DDPM.

[waydabber]

Hi there,

there are some examples here:

https://github.com/waydabber/BetterDisplay/wiki/Integration-features,-CLI#cli-examples

But I understand that the syntax might be difficult. What do you want to achieve?

Generally you should send DDC commands like this:

For example this sets the brightness directly via DDC to 70:

betterdisplaycli set -n=some_part_of_display_name -ddc=70 -vcp=luminance

For setting the brightness with the app in a managed way (use the configured brightness control method):

betterdisplaycli set -n=some_part_of_display_name -brightness=70%

[jswhisperer]

I tried the examples with a MBP no dice just "Failure" and tried sudo

Tried

betterdisplaycli set -n= Color LCD -brightness=70%
betterdisplaycli set -n= "Color LCD" -brightness=70%
betterdisplaycli set -n= color_lcd -brightness=70%

[waydabber]

betterdisplaycli set -n=built -brightness=70%

[jswhisperer]

brilliatnt I found that omitting the name too works for the default; not sure if I missed that -n=built if its not there probably awesome to give/add to example as many people might be on one monitor at least sometimes.Cheers I love your software!!

[waydabber]

Yes, if you omit the display identifier, the app will just try to apply the setting to all displays. You can also use comma to list more than one displays if needed.

[keigezellig]

I got also a Failed message when trying to switch an input.
I have 2 Dell U2723QE monitors, labeled 'DELL U2723QE 1' and 'DELL U2723QE 2' in the BetterDisplay UI and i can switch inputs of both screen without any problems.

When i try to switch the input of the '2' monitor with the CLI it gives 'Failed' as output. I tried both the --namelike and the --name switch with the full name but it doesn't work. However the '1' monitor does switch correctly.

Commands i tried:
~ /Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay set -namelike="DELL U2723QE 2" -feature=ddc -vcp=0x60 -value=0x1b

~ /Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay set -name="DELL U2723QE 2" -feature=ddc -vcp=0x60 -value=0x1b

Also trying to use the serial number as identifier doesn't work.

For my usecase i have to send 2 different commands to the different screens.

[keigezellig]

No, it doesn't. I tried one of the examples mentioned in the documentation (getting the luminance) but using the serial number(s) of my first monitor as reported by the UI, but it still fails:

/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay get -serial=4135304C -feature=ddc -vcp=luminance -value -max fails
/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay get -serial="4135304C" -feature=ddc -vcp=luminance -value -max fails
/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay get -alphanumericSerial=6NG4FP3 -feature=ddc -vcp=luminance -value -max fails
/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay get -alphanumericSerial="6NG4FP3" -feature=ddc -vcp=luminance -value -max fails

However:
/Applications/BetterDisplay.app/Contents/MacOS/BetterDisplay get -namelike=Dell -feature=ddc -vcp=luminance -value -max works, but got only the value of ONE monitor, i am expecting 2 values (for each monitor one)

[waydabber]

Does DDC generally work for the display? If so, does DDC read work? If there is a checksum error (as with many displays), get will fail.

[waydabber]

(note: you can start the app using the -v modifier via command line and check the logs, maybe you'll see what's wrong)

[keigezellig]

Yes, it does work. I can control both screens from the BetterDisplay UI.
I also tried the ddcutil command on my linux machine and it works just fine.

I tried the -v option but i doesn't give me more/better information:

[waydabber]

Oh, sorry, I meant adding the -v modifier to the main BetterDisplay app process - so you start the app with -v from the console and then send the command.