[linux] Introduction to Curl in Linux

What is Curl?

Curl is a command-line tool and library for transferring data with URLs. It supports various protocols like HTTP, HTTPS, FTP, FTPS, SCP, SFTP, and more. Curl is widely used in Linux systems to fetch and send data from and to servers. It can work without user interaction, making it suitable for automation tasks in shell scripts.

Basic Syntax

The basic syntax of Curl is curl [options] [URL]. The options can be used to customize the request, such as setting headers, following redirects, or specifying the output file. The URL represents the location of the resource you want to interact with.

Example Codes

1. Sending a GET request:

   curl https://api.example.com/data
   

   This command sends a GET request to https://api.example.com/data. The response will be displayed in the terminal.

2. Saving the response to a file:

   curl https://api.example.com/data -o response.txt
   

   This command saves the response from https://api.example.com/data to a file named response.txt.

3. Sending a POST request with data:

   curl -X POST https://api.example.com/submit -d "name=John&age=30"
   

   This command sends a POST request to https://api.example.com/submit with the form data “name=John&age=30”.

Applicable Versions

Curl is pre-installed in most Linux distributions, making it readily available for use. You can check the version of Curl installed on your system by running curl --version.

In conclusion, Curl is a powerful tool for making HTTP requests and transferring data in Linux systems. With its extensive features and flexibility, it is widely used by developers and system administrators for various tasks. Its simplicity and effectiveness make it a valuable asset in any Linux user’s toolkit.