MySQL エラー「ERROR 1290 (HY000): The MySQL server is running with the –secure-file-priv option so it cannot execute this statement」が発生した場合の対処法

select * from tbl1 into outfile "/tmp/tbl1.csv" fields terminated by ',';

ERROR 1290 (HY000): The MySQL server is running with the --secure-file-priv option so it cannot execute this statement

mysql> SELECT @@global.secure_file_priv;

+---------------------------+
| @@global.secure_file_priv |
+---------------------------+
| /var/lib/mysql-files/     |
+---------------------------+
1 row in set (0.00 sec)

select * from tbl1 into outfile "/var/lib/mysql-files/tbl1.csv" fields terminated by ',';

sudo cp /etc/mysql/mysql.conf.d/mysqld.cnf{,.`date +%y%m%d%H%M%S`}

sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf

<追加>
secure-file-priv = ""

sudo service mysql restart

mysql> SELECT @@global.secure_file_priv;

+---------------------------+
| @@global.secure_file_priv |
+---------------------------+
|                           |
+---------------------------+
1 row in set (0.00 sec)