In this tutorial, you will learn how to set and view curl headers with practical examples. When using curl, a command-line tool for transferring data with URLs, setting and viewing headers can be crucial for testing APIs, debugging, and simulating different web requests.
Table of Contents
Syntax and Explanation
To add a custom header to a curl request, use the -H or --header flag followed by the header key-value pair. To view the headers, use the -i, --include (to include the response headers in the output), or -D, --dump-header (to save the response headers to a file).
// Syntax to set a header curl -H "Header-Key: Header-Value" [URL] // Syntax to view response headers curl -i [URL] // Syntax to save response headers to a file curl -D headers.txt [URL]
Practical Examples
Example 1: Setting a Single Header
curl -H "Content-Type: application/json" https://api.example.com/data
Output:
{ "status": "success", "message": "Content type set to application/json" }
In this example, we’re specifying the Content-Type header to indicate that the data being sent is in JSON format.
Example 2: Setting Multiple CURL Headers
In this example, we demonstrate how to simultaneously set two headers, a common requirement when interacting with APIs that demand authentication. This active approach to header configuration allows developers to efficiently manage authentication tokens and other necessary information for seamless API integration. By following this example, users can quickly grasp the essential technique of setting multiple headers concurrently in their curl requests.
curl -H "Content-Type: application/json" -H "Authorization: Bearer YourToken" https://api.example.com/data
Output:
{ "status": "authorized", "message": "Multiple headers set successfully." }
Example 3: Viewing Response Headers
curl -i https://api.example.com/data
Output:
HTTP/1.1 200 OK Content-Type: application/json Set-Cookie: sessionId=abc123; Expires=Wed, 09 Jun 2021 10:18:14 GMT
By using the -i flag, this example returns the response body along with the headers, allowing you to view details such as cookies and content types.
Example 4: Saving Response Headers to a File
curl -D headers.txt https://api.example.com/data
Output in “headers.txt”:
HTTP/1.1 200 OK Content-Type: application/json Set-Cookie: sessionId=abc123; Expires=Wed, 09 Jun 2021 10:18:14 GMT
Instead of displaying them in the console, the -D flag saves the headers into the specified file
Conclusion
Understanding how to set and display headers in curl is vital for web development and API testing. Throughout this tutorial, we’ve covered the syntax and provided clear, actionable examples of setting and viewing headers. Armed with this knowledge, you should be able to integrate headers as necessary in your next development project or while troubleshooting APIs.
