mysql error : ERROR 1018 (HY000): Can't read dir of '.' (errno: 13)

You need to set ownership and permissions for directory:

chown -R mysql:mysql /var/lib/mysql/ #your mysql user may have different name
chmod -R 755 /var/lib/mysql/

Note: -R makes commands recursive - you may omit it, if there is no subdirs in /var/lib/mysql/.

For Us OS X Users, this should work:

sudo chown -R mysql:mysql /usr/local/mysql/
sudo chmod -R 755 /usr/local/mysql/

Edit: Depending on how you installed mysql your mileage my vary. I installed using the mysql community server dmg installer on mysql.com

If this doesn't work, try running which mysql to see where your mysql installation is located, and then replace /usr/local/mysql/ in the command above with whatever is before the 'bin' directory.

For example, on my system which mysql produces the following output: /usr/local/mysql/bin/mysql

so my path is /usr/local/mysql/

On CentOS/RedHat, you should do the same thing on a different path:

chown -R mysql:mysql /data/mysql/
chmod -R 755 /data/mysql/