-H/--header <header> (HTTP) Extra header to use when getting a web page. You may specify any number of extra headers. Note that if you should add a custom header that has the same name as one of the internal ones curl would use, your externally set header will be used instead of the internal one. This allows you to make even trickier stuff than curl would normally do. You should not replace internally set headers without knowing perfectly well what you're doing. Remove an internal header by giving a replacement without content on the right side of the colon, as in: -H "Host:". curl will make sure that each header you add/replace get sent with the proper end of line marker, you should thus not add that as a part of the header content: do not add newlines or carriage returns they will only mess things up for you. See also the -A/--user-agent and -e/--referer options. This option can be used multiple times to add/replace/remove multi- ple headers.
curl --header "X-MyHeader: 123" www.google.com
You can see the request that curl sent by adding the