PHP code that parses wp-config.php and returns mysql command for connection to the database.

db.php

<?php
/**
* Get database connection string from a wp-config.php file.
*
* Usage: php db.php /var/www/wp-config.php
*
* Output: mysql -h DB_HOST -u DB_USER -pDB_PASSWORD DB_NAME
*
* @author Jonas Björk <jonas.bjork@me.com>
* @date 2012-12-04
* @version 1.0
* @license http://opensource.org/licenses/GPL-2.0 The GNU General Public License (GPL-2.0)
*/

if ($argc > 1) {
        $file = $argv[1];
} else {
        print "\nYou can specify which wp-config.php file with:\ndb.php [PATH_TO_wp-config.php]\n";
        print "Trying to parse /var/www/wp-config.php now.\n\n";
        $file = '/var/www/wp-config.php';
}


$fh = @fopen($file, 'r');
if ($fh) {
        while (!feof($fh)) {
                $data[] = fgets($fh);
        }
        fclose($fh);

        foreach ($data as $line) {
                if (preg_match('/define.*(DB_USER|DB_HOST|DB_PASSWORD|DB_NAME)/', $line)) {
                        $conf[] = $line;
                }
        }

        if (@count($conf) < 3) {
                print "Could not find constants DB_HOST, DB_USER, DB_PASSWORD, DB_NAME\n";
                exit;
        }

        $php_code = implode($conf);
        eval($php_code);

        printf ("\nmysql -h %s -u %s -p%s %s\n\n", DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);

} else {
        printf("Could not open file %s for reading.\n", $file);
}

How clever :)