How to use cURL to send Cookies?

When using cURL to send HTTP requests, you can include cookies using the -b or --cookie option. This option enables you to add one or more cookies to the HTTP request. There are several ways to use this option:

1. Specify Cookies Directly in the Command Line

You can directly specify the cookie name and value in the command line. For instance, to send a cookie named sessionid with the value 12345 to a website, you can use the following command:

bash
curl -b "sessionid=12345" http://example.com

This command sends a GET request to http://example.com and includes the cookie sessionid=12345 in the request.

2. Read Cookies from a File

If you have multiple cookies or prefer not to display them directly in the command line, you can store cookies in a file. First, create a text file to store cookie information, such as:

shell
sessionid=12345; path=/; domain=.example.com
auth_token=abcdef; path=/; domain=.example.com

Then, use the -b option to specify this file:

bash
curl -b cookies.txt http://example.com

This will read all cookies from the cookies.txt file and include them when sending a request to http://example.com.

3. Manage Cookies in a Session with cURL

If you want to maintain and manage cookies across a series of requests, you can first use the -c option to retrieve cookies from the server and save them to a file, then use the -b option in subsequent requests to send these cookies. For example:

bash
# First request: retrieve cookies and save to cookiejar.txt
curl -c cookiejar.txt http://example.com/login

# Second request: send the saved cookies
curl -b cookiejar.txt http://example.com/dashboard

This method allows you to maintain login status or session information across multiple requests.

Summary

Using cURL to send cookies is a common technique when performing network requests, especially when handling authentication or session management. By directly specifying cookies in the command line, reading cookies from a file, and managing cookies across multiple requests, you can flexibly include necessary session information in HTTP requests. This is very useful for automation testing, web scraping, or any scenario requiring interaction with HTTP services.