MySQL trigger that will execute OS command

Download and Install lib_mysqludf_sys plugin 

Go to URL https://github.com/mysqludf/lib_mysqludf_sys

Click on Download zip or use wget to download.

wget https://github.com/mysqludf/lib_mysqludf_sys/archive/master.zip

Extract the downloaded plugin file and change directory to extracted directory.

unzip master.zip
cd lib_mysqludf_sys-master/

Compile module with command below.

gcc -m64 -fPIC -Wall -I/usr/include/mysql -I. \

-shared lib_mysqludf_sys.c -o /usr/lib64/mysql/plugin/lib_mysqludf_sys.so

Login to mysql and create function sys_exec and sys_eval on required database.

mysql -u root -p

use test;

CREATE FUNCTION sys_exec RETURNS int SONAME 'lib_mysqludf_sys.so';
CREATE FUNCTION sys_eval RETURNS int SONAME 'lib_mysqludf_sys.so';

Now for testing purpose we will create trigger that will execute after insert on each row of table tab_trig_test. First create table tab_trig_test.

use test;
create table tab_trig_test(
sn int,
name varchar(100)
);

Drop and create trigger that will execute after insert for each row on table tab_trig_test.
drop trigger if exists trig_test;

DELIMITER @@

CREATE TRIGGER trig_test 
AFTER INSERT ON tab_trig_test 
FOR EACH ROW 
BEGIN
 DECLARE cmd CHAR(255);
 DECLARE result int;
 SET cmd=CONCAT('echo ', new.name, ' > /tmp/haha',new.name);
 SET result = sys_exec(cmd);
END;
@@
DELIMITER ;

Now insert a row on table to verify that trigger has executed as expected.

insert into tab_trig_test values(2,'rajiv');

Verify that OS file has been created with command below.

\! cat /tmp/haha