If MySQL Startup Item is installed :

shell> sudo /Library/StartupItems/MySQL/MySQL start
(Enter your password, if necessary)
(Press Control-D or enter "exit" to exit the shell)

If MySQL Startup Item is NOT installed :

shell> cd /usr/local/mysql
shell> sudo ./bin/mysqld_safe
(Enter your password)
(Press CTRL+Z)
shell> bg
(Press CTRL+D to exit the shell)

http://dev.mysql.com/doc/refman/5.0/fr/mac-os-x-installation.html

how to start mysql under mac os x

mysql, mac

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