What is best way to check mysql status?

[Jose de Leon]

I have found at least three ways to check up/down status of MySQL.  I am
wondering what is considered the most reliable method, please comment
and add if you have another method.

1. Check for existence of PID file created by MySQL
2. Check for existence of mysql.sock
3. Verify connection via telnet to port 3306.

Thank you,
Jose de Leon