MySQL – How to Output Data to File on Linux

linuxMySQLpermissions

I am trying to output the data from an MySQL table to a file but getting permission errors:

$ pwd
/home/dotancohen
$ mkdir in
$ chmod 777 in/
$ mysql -ugs -p
mysql> USE someDatabase;
mysql> SELECT * FROM data INTO OUTFILE '/home/dotancohen/in/data.csv';
ERROR 1045 (28000): Access denied for user 'gs'@'localhost' (using password: YES)
mysql>

If the directory in question is chmodded to 777, then why cannot the MySQL user write the file? Interestingly enough, I cannot write to /tmp/ either.

EDIT:
It looks like the DB user has the proper MySQL permissions:

mysql> show grants;
+----------------------------------------------------------------------------------+
| Grants for gs@localhost                                                          |
+----------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'gs'@'localhost' IDENTIFIED BY PASSWORD 'somePassword'     | 
| GRANT ALL PRIVILEGES ON `gs\_%`.* TO 'gs'@'localhost'                            | 
+----------------------------------------------------------------------------------+
2 rows in set (0.01 sec)

Best Answer

According to MySQL Documentation on SELECT ... INTO OUTFILE

Any file created by INTO OUTFILE or INTO DUMPFILE is writable by all users on the server host. The reason for this is that the MySQL server cannot create a file that is owned by anyone other than the user under whose account it is running. (You should never run mysqld as root for this and other reasons.) The file thus must be world-writable so that you can manipulate its contents.

You should output the SELECT INTO OUTFILE to /var/lib/mysql as follows

SELECT * FROM data INTO OUTFILE 'data.csv';

Of course, you need to make sure you have FILE permission on gs@localhost.

There are two ways to have this permission given

METHOD #1

GRANT FILE ON *.* TO 'gs'@'localhost';

METHOD #2

UPDATE mysql.user SET File_priv = 'Y' WHERE user='gs' AND host='localhost';
FLUSH PRIVILEGES;

UPDATE 2012-05-01 07:09 EDT

To give yourself FILE privilege, do the following:

service mysql restart --skip-networking --skip-grant-tables
mysql <hit enter>
UPDATE mysql.user SET File_priv = 'Y' WHERE user='gs' AND host='localhost';
exit
service mysql restart
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