How do you refresh the MySQL configuration file without restarting?

You were so close! The kill -HUP method wasn't working for me either.

You were calling:

select @@global.max_connections;

All you needed was to set instead of select:

set @@global.max_connections = 400;

See:

http://www.netadmintools.com/art573.html

http://www.electrictoolbox.com/update-max-connections-mysql/

Try:

sudo /etc/init.d/mysql reload

or

sudo /etc/init.d/mysql force-reload

That should initiate a reload of the configuration. Make sureyour init.d script supports it though, I don't know what version of MySQL/OS you are using?

My MySQL script contains the following:

'reload'|'force-reload')
        log_daemon_msg "Reloading MySQL database server" "mysqld"
        $MYADMIN reload
        log_end_msg 0
        ;;