Advice on GRANT review on MySQL servers

Question

So I'm in for a bit of a tedious work. We have about 10 servers, each with about 4 MySQL users (plus mysql-root). All of these users have full access to their respective schema.

Now we've decided that they should only have the basic SELECT, INSERT, UPDATE rights (because that's all they need).

Looking at the REVOKE I get the feeling that since they've been added with GRANT ALL ON db.* I need to first revoke all privs, then grant the ones i need.

Now for the question. Is there a good way to do this for all users (on one server) at the same time or do I need to review them one by one?

EDIT:

The setup is something like this:

Server 1:

User dbuser_a with access to db_a

User dbuser_b with access to db_b ...

Server 2:

User dbuser_c with access to db_c

User dbuser_d with access to db_d ...

Answer 1

Create a ~/.my.cnf file to store your MySQL password, something like this:

[mysql]
user            = root
password        = secr3t
host            = ...

Remember to chmod 600 for it.

You can then revoke all privileges for all users with the shell snippet below:

mysql --skip-column-names -e 'select user,host from mysql.user;' | grep -v root | \
while read account; do
    mysql -e "revoke all privileges on db.* from '`echo $account | \ 
       awk '{ print $1 }'`'@'`echo $account | awk '{ print $2 }'`'; flush privileges;"
done

Do the same for granting privileges which you want.

---

UPDATE

You can also revoke all privileges: global, database, table, routine, ... from an user by removing the on db.* from the above:

mysql --skip-column-names -e 'select user,host from mysql.user;' | grep -v root | \
while read account; do
    mysql -e "revoke all privileges, grant option from '`echo $account | \ 
       awk '{ print $1 }'`'@'`echo $account | awk '{ print $2 }'`'; flush privileges;"
done