http://chriskief.com/2014/05/13/how-to-view-live-mysql-queries/

log_on.sql

mysql> SHOW VARIABLES LIKE "general_log%";
+------------------+-----------------------------------+
| Variable_name    | Value                             |
+------------------+-----------------------------------+
| general_log      | OFF                               |
| general_log_file | /opt/local/var/db/mysql56/out.log |
+------------------+-----------------------------------+
2 rows in set (0.00 sec)

mysql> SET GLOBAL general_log = 'ON';
Query OK, 0 rows affected (0.01 sec)