I read several posts here about this very issue. I tried several things including this:
unset TMPDIR
mysql_install_db --verbose --user=whoami --basedir="$(brew --prefix mysql)" --datadir=/usr/local/var/mysql --tmpdir=/tmp
and none have worked. How do I un-hose Mysql on OSX? And why is it pointed to some nonexistent pid file that is associated with my fios router?