cURL : Client URL

cURL is an open-source command-line tool used for transferring data between a client and a server.

• Supports HTTP, HTTPS, FTP, SCP, SFTP, and many more protocols

Basic cURL Commands

1. Fetch a Web Page

curl https://example.com

2. Download a File

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

3. Send a GET Request

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

4. Send a POST Request

curl -X POST https://api.example.com/users \
     -H "Content-Type: application/json" \
     -d '{"name": "Lokesh", "email": "lokesh@example.com"}'

5. Send a Request with Authentication

For API authentication, use:

curl -u username:password https://api.example.com/auth

Or use a token:

curl -H "Authorization: Bearer YOUR_ACCESS_TOKEN" https://api.example.com/data

6. Upload a File: Upload a file using the -F flag:

curl -X POST -F "file=@document.pdf" https://example.com/upload

7. Save Output to a File

Redirect the output to a file:

curl https://example.com -o output.html

Advanced cURL Usage

1. Handling Redirects

Follow redirects with:

curl -L https://shorturl.com

2. Setting Timeout

Set a request timeout:

curl --max-time 10 https://example.com

3. Debugging Requests

See detailed request and response logs:

curl -v https://example.com

4. Using cURL in Scripts

Automate API calls in scripts:

#!/bin/bash
response=$(curl -s https://api.example.com/data)
echo "API Response: $response"

cURL is an essential tool for developers, system administrators, and DevOps engineers. It simplifies API testing, file transfers, and automation tasks.