Always Geeky

If you need to set multiple HTTP headers when using curl, you cannot do so by delimiting them with a CRLF or similar line break. Doing so won’t work. You must set each header within a distinct -H parameter.

The correct method:

$ curl -I https://alwaysgeeky.com -H "Host:alwaysgeeky.com" -H "cache-control:no-cache"

Results:
HTTP/1.1 200 OK
Server: cloudflare-nginx
Date: Wed, 17 Oct 2012 20:21:01 GMT
Content-Type: text/html; charset=UTF-8
Connection: keep-alive
X-Pingback: https://alwaysgeeky.com/xmlrpc.php
Link: ; rel=shortlink
Vary: Accept-Encoding

Incorrect method:

$ curl -I https://alwaysgeeky.com -H "Host:alwaysgeeky.com\n\rcache-control:no-cache"

Results:
HTTP/1.1 409 Conflict
Server: cloudflare-nginx
Date: Wed, 17 Oct 2012 20:21:41 GMT
Content-Type: text/html
Connection: keep-alive
Cache-Control: max-age=6
Expires: Wed, 17 Oct 2012 20:21:47 GMT

Note that incorrect usage of the -H parameter will not result in 409 error every time. Each webserver, and webserver configuration, will respond to this type of invalid HTTP headers differently.