For some some reason brew does not link mysql and it complains about permission. I chmod the folder to 777 but I am still having the same issues
laptop$ brew install mysql Error:
mysql-5.5.27 already installed, it's just not linked laptop$ brew link mysql Linking /usr/local/Cellar/mysql/5.5.27... Warning: Could not link mysql. Unlinking...
Error: Could not symlink file: /usr/local/Cellar/mysql/5.5.27/lib/plugin /usr/local/lib is not writable. You should change its permissions. I figured what the problem was. It was issues with premission and I basically did this
sudo chown -R $(whoami) /usr/local/lib/ 
I believe You should:
sudo chmod 775 /usr/local/lib/ and make sure You are member of the file's group.
Not really an answer, but a comment that may help those who are pulling out hair chowning and chmoding like crazy and still getting "not writeable" errors at linking. For example, from $ brew doctor -d
Error: /usr/local/lib/pkgconfig isn't writable. This can happen if you "sudo make install" software that isn't managed by by Homebrew. If a formula tries to write a file to this directory, the install will fail during the link step. I suggest you check the linked file and it's dependencies and either delete them and reinstall via homebrew, or install the package without using homebrew.
In my system this worked perfectly.
chown -R $(whoami) /usr/local/share/ I am trying to give a general answer to the question. It happens that neither /usr/local/lib/ nor /usr/local/share/ gives error. You should look the exact directory that is not writable. It is mentioned right after "Error: Could not symlink". So execute the command for that directory.
chown -R $(whoami) [/bath/to/your/dir]