How to test which port MySQL is running on and whether it can be connected to?

grep port /etc/mysql/my.cnf ( at least in debian/ubuntu works )

or

netstat -tlpn | grep mysql

or

mysql -u user_name -puser_pass -e "SHOW variables LIKE 'port';"

verify

bind-address 127.0.0.1

in /etc/mysql/my.cnf to see possible restrictions

Using Mysql client:

mysql> SHOW GLOBAL VARIABLES LIKE 'PORT';

To find a listener on a port, do this:

netstat -tln

You should see a line that looks like this if mysql is indeed listening on that port.

tcp        0      0 127.0.0.1:3306              0.0.0.0:*                   LISTEN      

Port 3306 is MySql's default port.

To connect, you just have to use whatever client you require, such as the basic mysql client.

mysql -h localhost -u user database

Or a url that is interpreted by your library code.

netstat -tlpn

It will show the list something like below:

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1393/sshd
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      1859/master
tcp        0      0 123.189.192.64:7654     0.0.0.0:*               LISTEN      2463/monit
tcp        0      0 127.0.0.1:24135         0.0.0.0:*               LISTEN      21450/memcached
tcp        0      0 127.0.0.1:3306          0.0.0.0:*               LISTEN      16781/mysqld

Use as root for all details. The -t option limits the output to TCP connections, -l for listening ports, -p lists the program name and -n shows the numeric version of the port instead of a named version.

In this way you can see the process name and the port.