$ brew install mysql
Updating Homebrew...
==> Auto-updated Homebrew!
Updated 1 tap (homebrew/core).
==> Updated Formulae
ansible                 gitbucket               libdazzle               mysql@5.5               urh
b2-tools                gnome-builder           link-grammar            pgcli                   youtube-dl
blockhash               goreleaser              mapcrafter              phplint
ccrypt                  ipfs                    mikutter                quicktype
chrome-cli              jenkins-job-builder     mongo-cxx-driver        skinny
dxpy                    jpeg-turbo              mysql                   tup

==> Downloading https://homebrew.bintray.com/bottles/mysql-8.0.12.high_sierra.bottle.tar.gz
######################################################################## 100.0%
==> Pouring mysql-8.0.12.high_sierra.bottle.tar.gz
Error: The `brew link` step did not complete successfully
The formula built, but is not symlinked into /usr/local
Could not symlink share/man/man8/mysqld.8
/usr/local/share/man/man8 is not writable.

You can try again using:
  brew link mysql
==> /usr/local/Cellar/mysql/8.0.12/bin/mysqld --initialize-insecure --user=iosdevlog --basedir=/usr/local/Cellar/mysql
==> Caveats
We've installed your MySQL database without a root password. To secure it run:
    mysql_secure_installation

MySQL is configured to only allow connections from localhost by default

To connect run:
    mysql -uroot

To have launchd start mysql now and restart at login:
  brew services start mysql
Or, if you don't want/need a background service you can just run:
  mysql.server start
==> Summary
🍺  /usr/local/Cellar/mysql/8.0.12: 255 files, 233.0MB

$ sudo chown -R $(whoami) /usr/local
$ brew link mysql
Linking /usr/local/Cellar/mysql/8.0.12... 79 symlinks created
$ mysql_secure_installation