phpmyadmin using mysqli connects, but my php using mysqli errors out

Question

This is driving me nuts! I am getting the classic "Can't connect to local MySQL server through socket '/var/run/mysql4d/mysql4d.sock' (13)".

Everything I've dug up so far tells me my setup should be OK (eg, defining the sockets in php.ini and my.cnf, etc). Worse... phpmyadmin works with the same un/pw I am using in my own php. So obviously it's possible to connect, but I am screwing it up

I tried reverse-engineering the connection from phpmyadmin, but gave up it as too convoluted after a couple hours.

Can anyone offer some advice?

My configuration: Ubuntu 9.10 (Karmic), Apache 2.2, PHP 5.2.6, MySQL 4.1.22 (for legacy app reasons).

my.cnf (/var/lib/mysql4/my.cnf):

[client]
port = 3306
socket = /var/run/mysql4d/mysql4d.sock
[mysqld]
port = 3306
socket = /var/run/mysql4d/mysql4d.sock

php.ini (/etc/php5/apache2/php.ini):

[MySQL]
mysql.default_socket = /var/run/mysql4d/mysql4d.sock
[MySQLi]
mysql.default_socket = /var/run/mysql4d/mysql4d.sock

Same problem using mysql instead of mysqli, btw.

EDIT: I should mention that I have installed mysql4 alongside the ubuntu default install of php & mysql for use with a legacy application and it is this installation that I am having trouble connecting with. I tried this:

ini_set('mysql.default_socket', '/var/run/mysql4d/mysql4d.sock');

and now the connection goes thru, but all queries return empty sets. (cries in frustration)

Answer 1

This sounds like a permission problem in /var/run/mysql4d/mysql4d.sock. What user are you running this as? Are the permissions o.k. on file system level?

If you Google for the error messages, you'll find a lot of people who had this and it was always a permission issue, sometimes due to an activated SELinux. Check this thread for a few possible solutions.