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I'm setting up up a new MySQL server and I'd like to give it the same set of usernames, allowed hosts, and passwords as an existing server (which is going away).

Would it work to just do a dump of the users table and then load it on the new server?

Is there a better way than that?

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7 Answers 7

up vote 30 down vote accepted
oldserver$ mysqldump mysql > mysql.sql
newserver$ mysql mysql < mysql.sql
newserver$ mysql 'flush privileges;'

Should do it, remember to add -u $USER and -p$PASSWORD as required

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8  
The 'mysql' db contains lots more uses than just the grants. Make sure you want to transfer it all, before performing the above steps. –  Martijn Heemels Dec 20 '10 at 21:29
    
I'm getting the error You can't use locks with log tables. Is there any work around for this? –  Despertar Feb 6 '13 at 3:21
    
If only users are needed, I'd do mysqldump mysql user > mysql.sql –  Minras Mar 18 '13 at 15:04
    
I got unknown database flush privileges. What worked for me: mysqladmin reload. I suppose that service mysql reload or restart would also do the job. –  ufotds Feb 18 at 18:41
    
The first two lines will not acquire database-level, table-level, and column-level privileges. –  RolandoMySQLDBA May 26 at 14:13

I would take a look at the Percona Toolkit. The description of the pt-show-grants tool says it all...

pt-show-grants extracts, orders, and then prints grants for MySQL user accounts.

Why would you want this? There are several reasons.

The first is to easily replicate users from one server to another; you can simply extract the grants from the first server and pipe the output directly into another server.

The second use is to place your grants into version control....

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May i ask you make an example for this command? –  shgnInc May 26 at 9:58
    
pt-show-grants --user root --ask-pass –  matheeeny Jun 11 at 3:01

Whilst a dump of the mysql database would probably work, in my experience, properly documenting all the access and setting it up again with GRANT statements is much better. There are two benefits to doing it this way:

  1. You will understand your database security and how it is implemented.
  2. You will get to remove access that is no longer required.
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mysqldump will work, but since the mysql database uses ISAM, you can just copy the directory to the new server. You'll find this in different places, but the most common location for the mysql database will be /var/lib/mysql/mysql. Be sure to stop mysql on the new server, move the old directory out of the way, copy the directory and restart. An example using standard locations as root:

# /etc/init.d/mysqld stop
# cd /var/lib/mysql
# mv mysql ../mysql.backup
# rsync -a root@oldserver:/var/lib/mysql/mysql .
# /etc/init.d/mysql start
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1  
The 'mysql' db contains lots more uses than just the grants. Make sure you want to transfer it all, before performing the above steps. –  Martijn Heemels Dec 20 '10 at 21:29

The accepted answer (using mysqldump to backup mysql.user table) is a very dangerous approach if you are migrating to a new server version.

I did that in the past (migrating users from Mysql 4 to Mysql 5.1), and later I had problems trying to grant or modify privileges to my database users.

This happens because mysql.users table structure differs between mysql server versions, as explained here:

http://dba.stackexchange.com/a/16441/18472

So, take care if you are upgrading your server version. Some more hints here:

http://stackoverflow.com/a/13218162/710788

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it is so simple to run grant commands. It is like

GRANT ALL on database.table to "user"@"host" identified by "password"

so

GRANT ALL on database.* to "jack"@"localhost" identified by "somepass"

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