How to Use the cURL Program

What is cURL?

The command line is a screen where you type commands. cURL lets you talk to a website from there. It can download a file, check if a site is up, or send data to a web address. It works like a browser that has no pictures.

Check that cURL is installed

Open a terminal. On Windows 10 and later, use Command Prompt. Type:

curl --version

This prints the cURL version. If it is missing on Ubuntu, install it with sudo apt install curl.

Basic commands

1. Show a web page's code:

   curl https://example.com

   This command prints the page source on your screen.
2. See only the headers:

   curl -I https://example.com

   Headers are short notes the server sends before the page. The first line shows the status, such as 200 OK.
3. Save a file with its own name:

   curl -O https://example.com/file.zip

4. Save a file with a name you choose:

   curl -o mycopy.zip https://example.com/file.zip

5. Follow a redirect:

   curl -L http://example.com

   A redirect sends you from one address to another. The -L option tells cURL to follow it.
6. Show details of the connection:

   curl -v https://example.com

   The -v stands for verbose. It prints every step and is great for fixing problems.

Send data

curl -X POST -d "name=Sam" https://example.com/form

This command sends the text name=Sam to a web address, like a filled-in form.

Handy status codes

Quick recap

• cURL fetches web content from the command line.
• curl -I shows headers.
• curl -O downloads a file.
• curl -L follows redirects.
• curl -v helps you find problems.