How to Download Files Using POST Method in Ubuntu Linux

This article demonstrates how to use the curl command in Ubuntu to download files while specifying HTTP methods like POST or PUT instead of the default GET. It covers the necessary syntax, flags for sending data, and how to save the server response to a local file efficiently.

Using Curl to Change HTTP Methods

The curl tool is pre-installed on most Ubuntu systems and allows you to specify custom HTTP methods. To download a file using a method other than GET, you primarily need the -X flag to define the method and the -o flag to save the output to a file.

Downloading with a POST Request

To download a file using the POST method, open your terminal and use the following command structure. Replace the URL with your target endpoint and the filename with your desired output name.

curl -X POST -o downloaded_file.zip https://example.com/api/file

If the server requires data to be sent along with the POST request, use the -d flag to include form data or JSON.

curl -X POST -d "id=123" -o result.txt https://example.com/api/data

Downloading with a PUT Request

For endpoints that require a PUT method to retrieve or generate a resource, change the -X flag accordingly.

curl -X PUT -o output_file.json https://example.com/api/resource

Understanding the Command Flags

• -X: Specifies the custom HTTP method (e.g., POST, PUT, DELETE).
• -o: Defines the local filename where the response body will be saved.
• -d: Sends data to the server in the request body.
• -H: Adds custom headers if authentication or content-type specification is required.

Verifying the Download

Once the command executes, check your current directory to ensure the file was saved correctly. You can list the files using ls or check the file type using file downloaded_file.zip to confirm the content matches the expected format.