curl "http://www.example.com?$(date +%s)"
I think specify HEADER in request is difficult to disable caching perfectly. Same as Stackoverflow's below answer.
The -H 'Cache-Control: no-cache' argument is not guaranteed to work because the remote server or any proxy layers in between can ignore it. If it doesn't work, you can do it the old-fashioned way, by adding a unique querystring parameter. Usually, the servers/proxies will think it's a unique URL and not use the cache. wisbucky