[Ubuntu] XAMPP: Couldn't start MySQL!

After i downloaded the lampp and unpacked it in /opt/lampp, then i try to run it, 

sudo /opt/lampp/lampp start

I got these message:

Starting XAMPP for Linux 1.7.3a...
XAMPP: Starting Apache with SSL (and PHP5)...
XAMPP: Starting MySQL...
XAMPP: Couldn't start MySQL!
XAMPP: Starting ProFTPD...
XAMPP for Linux started.

MySQL can't start!

Then i check the log in /opt/lampp/var/mysql/

101117 23:54:57 mysqld_safe Starting mysqld daemon with databases from /opt/lampp/var/mysql
101117 23:54:57 [Note] Plugin 'FEDERATED' is disabled.
101117 23:54:57 [ERROR] Can't open shared library 'libpbxt.so' (errno: 0 API version for STORAGE ENGINE plugin is too different)
101117 23:54:57 [Warning] Couldn't load plugin named 'PBXT' with soname 'libpbxt.so'.
101117 23:54:57  InnoDB: Started; log sequence number 0 44233
101117 23:54:57 [ERROR] Can't start server : Bind on unix socket: Permission denied
101117 23:54:57 [ERROR] Do you already have another mysqld server running on socket: /opt/lampp/var/mysql/mysql.sock ?
101117 23:54:57 [ERROR] Aborting

101117 23:54:57  InnoDB: Starting shutdown...
101117 23:54:58  InnoDB: Shutdown completed; log sequence number 0 44233
101117 23:54:58 [Note] /opt/lampp/sbin/mysqld: Shutdown complete

101117 23:54:58 mysqld_safe mysqld from pid file /opt/lampp/var/mysql/davidhhuan-ThinkPad-T410.pid ended

Searching it in google, it seems that mysql does not have the permission to do something.

There are two way to achieve it.

One:

sudo chown mysql.mysql -R /opt/lampp/var/mysql

Two:

sudo chmod 777 /opt/lampp/var/mysql -R

I followed the second way, then MySQL can run well!

There is another issue when one day i meet!

110407 01:18:50 mysqld_safe Starting mysqld daemon with databases from /opt/lampp/var/mysql
110407  1:18:50 [Note] Plugin 'FEDERATED' is disabled.
110407  1:18:50 [ERROR] Can't open shared library 'libpbxt.so' (errno: 0 API version for STORAGE ENGINE plugin is too different)
110407  1:18:50 [Warning] Couldn't load plugin named 'PBXT' with soname 'libpbxt.so'.
110407  1:18:50  InnoDB: Started; log sequence number 0 22074476
/opt/lampp/sbin/mysqld: File './mysql-bin.000074' not found (Errcode: 2)
110407  1:18:50 [ERROR] Failed to open log (file './mysql-bin.000074', errno 2)
110407  1:18:50 [ERROR] Could not open log file
110407  1:18:50 [ERROR] Can't init tc log
110407  1:18:50 [ERROR] Aborting

110407  1:18:50  InnoDB: Starting shutdown...
110407  1:18:51  InnoDB: Shutdown completed; log sequence number 0 22074476
110407  1:18:51 [Note] /opt/lampp/sbin/mysqld: Shutdown complete
110407 01:18:51 mysqld_safe mysqld from pid file /opt/lampp/var/mysql/davidhhuan-ThinkPad-T410.pid ended 

From the error log, we can know that MySQL is looking in the mysql-bin.index file and it cannot find the log files that are listed within the index. This will keep MySQL from starting, but the fix is quick and easy. In the /var/lampp/var/mysql, there are so many mysql-bin.0000** files, so i just copy one, and rename it to mysql-bin.000074, then i fixed this issue!