cURL: Show only the response headers

curl -s -D - -o /dev/null http://example.com

Example output:

HTTP/1.1 200 OK
Accept-Ranges: bytes
Age: 460126
Cache-Control: max-age=604800
Content-Type: text/html; charset=UTF-8
Date: Mon, 06 May 2024 12:11:41 GMT
Etag: "3147526947"
Expires: Mon, 13 May 2024 12:11:41 GMT
Last-Modified: Thu, 17 Oct 2019 07:18:26 GMT
Server: ECAcc (dcd/7D21)
Vary: Accept-Encoding
X-Cache: HIT
Content-Length: 1256