Garbage In Garbage Out

Tech tips & other words

Tag: Mac OS

Clear Mac OS DNS cache via command line

October 28, 2025 / / 0 Comments

The method for clearing or flushing the local cache in Mac OS has changed over the years. Here are all the Mac OS versions on one page that details how to clear Mac OS DNS cache via command line.

TLDR; Add this alias to your .zshrc file:

alias flushdns="sudo killall -HUP mDNSResponder;sudo killall mDNSResponderHelper;sudo dscacheutil -flushcache;say 'cache flushed' -v Tessa -r 229"

Then issue this command:

source ~/.zshrc

And now you can run this command and get nice audio confirmation:

flushdns

Clear your DNS cache on macOS Tahoe 26, macOS Sequoia 15, macOS Sonoma 14, macOS Ventura 13, macOS Monterey 12, macOS Big Sur 11, macOS 10.15 Catalina, macOS 10.14 Mojave, macOS 10.13 High Sierra, macOS 10.12 Sierra, OS X 10.11 El Capitan, OS X 10.10 Yosemite, OS X 10.9 Mavericks, OS X 10.8 Mountain Lion, OS X 10.7 Lion, OS X 10.6 Snow Leopard, and OS X 10.5 Leopard using the following Terminal commands:

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High impedance headphones on MacBook Pro 2021

November 18, 2021 / / 0 Comments

Good news for audiophiles out there. High impedance headphones are supported on m1 MacBook Pros. Apple’s new laptops feature an adaptive voltage headphone amplifier, meaning it optimizes itself to the headphones you’re using. With these two models, gone is the concern whether 80 ohm or 250 ohm headphones will work.

“When you connect headphones with an impedance of less than 150 ohms, the headphone jack provides up to 1.25 volts RMS. For headphones with an impedance of 150 to 1k ohms, the headphone jack delivers 3 volts RMS. This may remove the need for an external headphone amplifier.”

So, if you love Beyerdynamic’s DT 990 Pro 250 ohm Open-back Studio Headphones, you can rest assured that your new MacBook Pro will power them with aplomb.

 

Make your Mac chime at startup again

April 22, 2020 / / 0 Comments

I miss the startup chime on my MacBook Pro. Make your Mac chime on startup again!

To enable it, open up terminal and type:

sudo nvram StartupMute=%00

To disable it, either reset your parameter RAM by pressing Command-Option-P-R at startup, or in terminal type:

sudo nvram StartupMute=%01

Mute system audio when increasing/decreasing volume

November 26, 2007 / / 2 Comments

Here’s a cool tip from The Distant Librarian on how to silence the audio feedback you get when using the keyboard to increase or decrease the volume in Mac OS X.

Hold down the shift key while depressing the volume keys will silence the auditory feedback while raising and lowering the volume, but still show the visual cue.

Other cool tricks:

Hold down option while clicking one of the sound keys to access the Sound system preferences.

Get more granular volume control by holding down shift-option while clicking one of the sound keys to increase/decrease volume in 1/4 the normal increments. Normal, the Mac provides 16 volume levels. Holding down shift-option gives you 64 increments.

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