mysql之忘记密码篇

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There is 2 issues - why can’t I log in as root to start with, and why can I not use 'mysqld_safe` to start mySQL to reset the root password.

I have no answer to setting up the root password during installation, but here’s what you do to reset the root password

Edit the initial root password on install can be found by running

grep ‘temporary password’ /var/log/mysqld.log

http://dev.mysql.com/doc/refman/5.7/en/linux-installation-yum-repo.html

systemd is now used to look after mySQL instead of mysqld_safe (which is why you get the -bash: mysqld_safe: command not found error - it’s not installed)

The user table structure has changed.

So to reset the root password, you still start mySQL with --skip-grant-tables options and update the user table, but how you do it has changed.

1. Stop mysql:
   systemctl stop mysqld

2. Set the mySQL environment option
   systemctl set-environment MYSQLD_OPTS="–skip-grant-tables"

3. Start mysql usig the options you just set
   systemctl start mysqld

4. Login as root
   mysql -u root

5. Update the root user password with these mysql commands
   mysql> UPDATE mysql.user SET authentication_string = PASSWORD(‘MyNewPassword’)
   -> WHERE User = ‘root’ AND Host = ‘localhost’;
   mysql> FLUSH PRIVILEGES;
   mysql> quit

*** Edit ***
As mentioned my shokulei in the comments, for 5.7.6 and later, you should use
mysql> ALTER USER ‘root’@‘localhost’ IDENTIFIED BY ‘MyNewPass’;
Or you’ll get a warning

6. Stop mysql
   systemctl stop mysqld

7. Unset the mySQL envitroment option so it starts normally next time
   systemctl unset-environment MYSQLD_OPTS

8. Start mysql normally:
   systemctl start mysqld

Try to login using your new password:
7. mysql -u root -p

Reference

As it says at http://dev.mysql.com/doc/refman/5.7/en/mysqld-safe.html,
Note
As of MySQL 5.7.6, for MySQL installation using an RPM distribution, server startup and shutdown is managed by systemd on several Linux platforms. On these platforms, mysqld_safe is no longer installed because it is unnecessary. For more information, see Section 2.5.10, “Managing MySQL Server with systemd”.

Which takes you to http://dev.mysql.com/doc/refman/5.7/en/server-management-using-systemd.html where it mentions the systemctl set-environment MYSQLD_OPTS= towards the bottom of the page.

The password reset commands are at the bottom of http://dev.mysql.com/doc/refman/5.7/en/resetting-permissions.html

如果觉得不够详细的，可以直接从这里找答案：https://stackoverflow.com/questions/33510184/change-mysql-root-password-on-centos7/34207996#34207996