Disable boot sound help

[gogreen1]

I'm using a MacBook Air, 13-inch, 2017.

I've tried several suggestions I've found in Google searches, but none works. I've tried:

sudo nvram SystemAudioVolume=%01
sudo nvram SystemAudioVolume=%00
sudo nvram SystemAudioVolume=" "
sudo nvram SystemAudioVolume=%80

The last one worked after one shutdown and boot, but on restart and shutdown-boot, the sound played again.

What am I doing wrong?

Thanks.

 

[Erehy Dobon]

.

 

[gogreen1]

I use Onyx, and I didn't see that! Thanks, Erehy Dobon. I'll shut down and restart a few times to test the Onyx setting.

 

[Gregg2]

Just turned mine off.
Great tip!

 

[gogreen1]

So far, so good. The Onyx setting is working. No chime on startups after shutdowns or on restarts.

 

[bogdanw]

I think Onyx just sets nvram value SystemAudioVolume to %80, so the Turn On button is equivalent to sudo nvram -d SystemAudioVolume and the Turn Off button is sudo nvram SystemAudioVolume=%80
The value can be read with sudo nvram SystemAudioVolume, the default value was 0 (zero). The other nvram variable SystemAudioVolumeDB remains %f0

 

[gogreen1]

The Onyx setting is still working. But sudo nvram SystemAudioVolume reports "Z" 🤔

 

[Erehy Dobon]

.

 

[gogreen1]

Does it really matter what the nvram command reply is if it's working?

Maybe. I don't know. That's why I reported it.

 

[bogdanw]

Does it really matter what the nvram command reply is if it's working?

Not to me, I don't need it. But it is still interesting to know what an app does to your system, especially when you trust it with your password and the power to run sudo commands.

The Onyx setting is still working. But sudo nvram SystemAudioVolume reports "Z" 🤔

I've tested in a VMware virtual machine, so maybe Onyx is using different commands for different Macs.