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su - setup.admin
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Updating Homebrew may result in error,
brew update Error: The /usr/local directory is not writable. Even if this directory was writable when you installed Homebrew, other software may change permissions on this directory. For example, upgrading to OS X El Capitan has been known to do this. Some versions of the "InstantOn" component of Airfoil or running Cocktail cleanup/optimizations are known to do this as well. You should probably change the ownership and permissions of /usr/local back to your user account.
Except running this gives the following error,
sudo chown -R setup.admin:admin /usr/local/ chown: /usr/local: Operation not permitted
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