When using cURL for HTTP requests, by default, cURL automatically adds several standard HTTP headers, such as User-Agent, Accept, Host, etc. If you need to remove or modify these default headers, you can use options provided by cURL to achieve this.
Method One: Using the -H Option
The most straightforward approach is to use the -H or --header option to set custom headers. To remove a specific header, set its value to an empty string. For example, to remove User-Agent, you can do the following:
curl -H "User-Agent:" http://example.com
In this example, setting the value of User-Agent to empty instructs cURL not to send this header.
Method Two: Using a Configuration File
If you frequently use cURL in scripts and need to remove certain headers multiple times, consider using a configuration file to set them uniformly. Add the corresponding -H settings to the cURL configuration file (typically located at ~/.curlrc):
-H "User-Agent:"
This way, the configuration is applied every time you use the cURL command, thus preventing the User-Agent header from being sent.
Example Application Scenario
Suppose you are developing an application that interacts with a third-party API requiring all requests to exclude the User-Agent header. You can add -H "User-Agent:" to your request script to ensure compliance with the API's requirements. This approach also helps pass security checks, especially when the API employs header-based security policies.
Tips
Ensure there is no space immediately after : when using the -H parameter; this ensures the header value is correctly set to empty. For complex requests, use the -v or --verbose option to view the full request sent by cURL, including all headers, to verify your custom settings take effect.
In summary, by using the -H option, you can flexibly control the HTTP headers sent by cURL, including removing default headers or adding custom ones, to meet various network request requirements.