How to display request headers with command line curl

To display the request headers of an HTTP request using the command-line tool curl, we typically use the -v (or --verbose) option. This option enables curl to show more detailed information during the request process, including both request headers and response headers.

For example, if you want to view the request headers for accessing http://example.com, you can use the following command:

bash
curl -v http://example.com

After executing this command, curl displays comprehensive process information, including the request headers. Specifically, the lines following the > symbol indicate the request headers sent to the server. For instance:

text
> GET / HTTP/1.1
> Host: example.com
> User-Agent: curl/7.64.1
> Accept: */*

This output confirms that the curl command sent a GET request to example.com, with request headers containing fields such as Host, User-Agent, and Accept.

Additionally, if you only want to view the request headers without sending the full request body, you can use the -I or --head option to issue a HEAD request. This approach ensures curl retrieves only the header information without downloading the content. For example:

bash
curl -I http://example.com

This command requests the response headers of example.com and displays them. However, the key focus is on how it sends only the request headers. This is particularly useful for inspecting the response headers of a web server (not the request headers), such as verifying resource existence, determining resource types, and checking server response statuses.