$ mysql_install_db --datadir=./foo

$ mysqld --port=5555 --datadir=./foo &

$ mysql --user=root --port=5555 --password=
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

$ mysqladmin -u root -P 5555 password foo
mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'root'@'localhost' (using password: NO)'

SELECT user, host, password FROM mysql.user WHERE user = 'root';

$ mysqld --port=5555 --datadir=./foo --socket=./sock &

$ mysql --socket=./sock --user=root --port=5555