Zaraz po instalacji hasło do MySQL jest puste
Dlatego trzeba je zmienić na jakiekolwiek
1. Logujemy się na root
2. Uruchamiamy klienta mysql z linii komend
3. W nim zmieniamy hasło
4. Restartujemy serwer mysql

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root@host # mysql
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 1 to server version: 3.23.41
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql> USE mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> UPDATE user
-> SET password=password("newpassword")
-> WHERE user="root";
Query OK, 2 rows affected (0.04 sec)
Rows matched: 2 Changed: 2 Warnings: 0
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)
mysql> exit;
root@host # /usr/local/etc/rc.d/mysql-server stop
root@host # /usr/local/etc/rc.d/mysql-server start
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