msql_pconnect() acts very much like msql_connect() with two major differences.
First, when connecting, the function would first try to find a (persistent) link that's already open with the same host. If one is found, an identifier for it will be returned instead of opening a new connection.
Second, the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use (msql_close() will not close links established by this function).
The hostname can also include a port number. e.g. hostname,port.
If not specified, the connection is established by the means of a Unix domain socket, being then more efficient then a localhost TCP socket connection.
Note: While this function will accept a colon (:) as a host/port separator, a comma (,) is the preferred method.