When I tried to install python onto homebrew it downloaded it and then an error message popped up at the end that stopped it from completing. When I try to do it again it asks me to do:
$ brew link python
After entering that the same error message appears:
permission denied @ dir_s_mkdir - /usr/local/lib
I have tried to do:
$ sudo chown -R $(whoami) /usr/local
And I get an error message that reads:
chown: /usr/local: Operation not permitted
sudo mkdir /usr/local/Frameworks
sudo chown $USER /usr/local/Frameworks
And then try re-installing python. This worked absolutely fine for me.
Run this, and follow its suggestions:
brew doctor
In my case, it wanted me to run:
sudo mkdir -p /usr/local/sbin /usr/local/Frameworks
sudo chown -R $(whoami) /usr/local/sbin /usr/local/Frameworks
In my case with MacOS 10.14 fresh installation in a new machine:
brew doctor
And it suggests:
sudo mkdir -p /usr/local/lib /usr/local/sbin
sudo chown -R $(whoami) /usr/local/lib /usr/local/sbin
Command for users on macOS
bash/zsh:
sudo chown -R $(whoami) $(brew --prefix)/*
fish:
sudo chown -R (whoami) (brew --prefix)/*
I reinstalled brew and fixed the issue.
to uninstall use the following command.
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/uninstall)"
and to install brew again.
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
brew doctor
This command, as suggested by Chris above in the comments, solved almost ALL my home-brew issues running on a Mac Mini 2011 5,1 unofficially running MacOS Mojave. Simply enter that and follow all directions that terminal prints