XAMPP: Couldn't start MySQL! on Ubuntu or Linux Mint, be calm :)

"Warning: World-writable config file '/opt/lampp/etc/my.cnf' is ignored
XAMPP: Couldn't start MySQL!"

first step write this command on terminal :
#chown -hR root /opt/lampp
and
#chmod 777 -R /opt/lampp
restart the lampp
#opt/lampp/lampp restart
if still show this message

Warning: World-writable config file '/opt/lampp/etc/my.cnf' is ignored
XAMPP: Couldn't start MySQL!

write this second step on terminal :
# chmod 644 /opt/lampp/etc/my.cnf
and
# /opt/lampp/lampp restart

Stopping XAMPP for Linux 1.8.1...
XAMPP: Stopping Apache with SSL...
XAMPP: XAMPP-MySQL is not running.
XAMPP: Stopping ProFTPD...
XAMPP stopped.
Starting XAMPP for Linux 1.8.1...
XAMPP: Starting Apache with SSL (and PHP5)...
XAMPP: Starting MySQL...
XAMPP: Starting ProFTPD...
XAMPP for Linux started.