How to Export & Import Existing User (with its Privileges!)

Question

I have an existing MySQL instance (test), containing 2 databases and a few users each having different access privileges to each database.

I now need to duplicate one of the databases (into production) and the users associated with it.

Duplicating the database was easy:

Export:

mysqldump --no-data --tables -u root -p secondb >> secondb_schema.sql

Import:

mysql -u root -p -h localhost secondb < secondb_schema.sql

I didn't find, however, a straightforward way to export and import users, from the command line (either inside or outside mysql).

How do I export and import a user, from the command line?

---

Update: So far, I have found manual (and thus error prone) steps for accomplishing this:

-- lists all users
select user,host from mysql.user;

Then find its grants:

-- find privilege granted to a particular user
show grants for 'root'@'localhost'; 

Then manually create user with the grants listed in the result of the 'show grants' command above.

I prefer a safer, more automated way. Is there one?

Solution 1

One of the easiest ways I've found to export users is using Percona's tool pt-show-grants. The Percona tool kit is free, easy to install, and easy to use, with lots of documentation. It's an easy way to show all users, or specific users. It lists all of their grants and outputs in SQL format. I'll give an example of how I would show all grants for test_user:

shell> pt-show-grants --only test_user

Example output of that command:

GRANT USAGE ON *.* TO 'test_user'@'%' IDENTIFIED BY PASSWORD '*06406C868B12689643D7E55E8EB2FE82B4A6F5F4';
GRANT ALTER, INSERT, LOCK TABLES, SELECT, UPDATE ON `test`.* TO 'test_user'@'%';

I usually rederict the output into a file so I can edit what I need, or load it into mysql.

Alternatively, if you don't want to use the Percona tool and want to do a dump of all users, you could use mysqldump in this fashion:

shell> mysqldump mysql --tables user db > users.sql

Note: --flush-privileges won't work with this, as the entire db isn't being dumped. this means you need to run it manually.

shell> mysql -e "FLUSH PRIVILEGES"

Solution 2

mysql -u<user> -p<password> -h<host> -e"select concat('show grants for ','\'',user,'\'@\'',host,'\'') from mysql.user" > user_list_with_header.txt
sed '1d' user_list_with_header.txt > ./user.txt
while read user; do  mysql -u<user> -p<password> -h<host> -e"$user" > user_grant.txt; sed '1d' user_grant.txt >> user_privileges.txt; echo "flush privileges" >> user_privileges.txt; done < user.txt
awk '{print $0";"}'  user_privileges.txt >user_privileges_final.sql
rm user.txt user_list_with_header.txt user_grant.txt user_privileges.txt

Above script will run in linux environment and output will be user_privileges_final.sql that you can import in new mysql server where you want to copy user privileges.

UPDATE: There was a missing - for the user of the 2nd mysql statement.

Solution 3

Yet another bash one-liner for linux that you can use instead of the Percona tool:

mysql -u<user> -p<password> -h<host> -N mysql -e "select concat(\"'\", user, \"'@'\", host, \"'\"), coalesce(password, authentication_string) from user where not user like 'mysql.%'" | while read usr pw ; do echo "GRANT USAGE ON *.* TO $usr IDENTIFIED BY PASSWORD '$pw';" ; mysql -u<user> -p<password> -h<host> -N -e "SHOW GRANTS FOR $usr" | grep -v 'GRANT USAGE' | sed 's/\(\S\)$/\1;/' ; done

Solution 4

In complement of @Sergey-Podushkin 's answer, this shell script code is workin for me:

mysql -u<user> -p<password> -N mysql -e "select concat(\"'\", user, \"'@'\", host, \"'\"), authentication_string from user where not user like 'root'" | while read usr pw ; do mysql -u<user> -p<password> -N -e "SHOW GRANTS FOR $usr" | sed 's/\(\S\)$/\1;/'; done 

Solution 5

In mysql 5.7 and later you can use this.

mysqlpump -uroot -p${yourpasswd} --exclude-databases=% --users

This will generate a sql format output that you can redirect to mysql_users.sql.

Note that it is mysqlpump not mysqldump.

View more solutions

Comments

[Hugo H]

There is a lot of flush privileges; empty lines but it works. Thanks!

[robsch]

Download tools containing pt-show-grants from here, Doc is here

[Admin]

i was really anxious to run this (hard to read script), but it worked, kudos!

[trey-jones]

Note that for MySQL 5, you will need to use the 2.x version of this tool, rather than 3.x

[danemacmillan]

@threeve I assume you suggest that because pt-show-grants no longer provides the password with that combination?

[trey-jones]

@danemacmillan My memory is hazy - I believe 3.x is compatible with mysql 8+. Probably my comment extends from trying the latest release with our server (5.x) and finding that "it didn't work".

[CodingInTheUK]

How to add backticks? some columns use keywords so backticks are needed. GRANT SELECT, UPDATE (ssl_key, ssl, ssl_request, ssl_action, ssl_letsencrypt, ssl_cert) ON database.table TO 'user'@'hostname'; ssl is a reserved work, I cant change the column its not my project but it breaks this script, as will any reserved word.

[Toothbrush]

@Chris GRANT SELECT, UPDATE (`ssl_key`, `ssl`, `ssl_request`, `ssl_action`, `ssl_letsencrypt`, `ssl_cert`) ON `database`.`table` TO 'user'@'hostname';

[Novocaine]

Really handy script, the comments in the gist for code tweaks are necessary, after which it does exactly what I need.

[TommyPeanuts]

Your IDENTIFIED BY ', authentication_string, doesn't work on the import as it's missing enclosing commas around authentication_string.

[RedScourge]

authentication_string is not a string, rather it is a column name of a field we want in the table mysql.user, so it should indeed work without additional quotation marks.

[TommyPeanuts]

when I try running the SQL, the hashes don't turn up in that column but the literal string does unless I put quotes around it. Also, the resulting grants don't seem to work anyway. I have had to use the percona tool instead.

[RedScourge]

Oh, I see what you mean now. Seems I do have quotes there actually in the code I'm running. I will update the answer. As for the grants not working, I have run into problems with certain versions of MySQL, particularly lower ones, or where your hashes were originally generated in a much older version. In the latter case I had to re-set all the passwords when migrating very old credentials, then the hashes output as expected. Other than that, it works fine for me in 5.7.32 as I use it as part of my automated backups for recreating everything.

[TommyPeanuts]

interesting - I'm using 5.7.32 but some of the hashes were generated in an older version so perhaps that's it.

[RedScourge]

I think the hashes that gave me problems were from a pretty old version, like 5.5.30 or something.

[TommyPeanuts]

It's possible they could have come from that early a version. BTW when I tried the SQL output from your script (once I'd fixed the quote thing) I didn't get any errors, just that the users couldn't log in.

[amicoderozer]

Thanks, this is perfect for MySql 8, Sergey's won't work in version 8 because there isn't field password in mysql.user table

[Diggi55]

Why would you force this into a one-line?? The answer is barely readable

[Sergey Podushkin]

@Diggi55 just because I can and want to and just because it's convenient when you work in command line and retrieve the whole command from the history as one line rather than set of commands. You can put this one-liner into file, break it to multiple line and save as script if one-liner doesn't fit your needs.

[Dennis V]

mysqldump --version mysqldump Ver 8.0.27-0ubuntu0.20.04.1 for Linux on x86_64 ((Ubuntu)) # mysqldump --users mysqldump: [ERROR] unknown option '--users'.

[Pablo Luna]

NOT mysqldump but mysqlpump.... pump not dump