@Ajit5ingh
cURL Commands
Essential HTTP client commands every developer should know
What is cURL?
cURL is a command-line tool for making HTTP requests. Think of it as your browser's developer tools, but for the terminal. It lets you send requests, download files, and test APIs without opening a browser.
Basic Requests
Simple GET Request
The most basic way to fetch data from an API
curl https://api.github.com/users/octocat
{
"login": "octocat",
"id": 1,
"name": "The Octocat"
}
POST Request with JSON
Send data to create or update resources
curl -X POST \
-H "Content-Type: application/json" \
-d '{"name":"John","email":"john@example.com"}' \
https://api.example.com/users
Download a File
Save content directly to your local machine
curl -o filename.zip https://example.com/file.zip
# Or use the remote filename
curl -O https://example.com/file.zip
Authentication Examples
Basic Auth
Username and password authentication
curl -u username:password https://api.example.com/data
# Or encode it yourself
curl -H "Authorization: Basic dXNlcjpwYXNz" https://api.example.com/data
Bearer Token
API token authentication (most common for modern APIs)
curl -H "Authorization: Bearer your-token-here" \
https://api.example.com/protected
API Key in Header
Custom header for API key authentication
curl -H "X-API-Key: your-api-key" \
https://api.example.com/data
Advanced Usage
Follow Redirects
Automatically follow HTTP redirects
curl -L https://bit.ly/short-url
Show Response Headers
Include headers in the output for debugging
curl -i https://api.example.com/data
# Or just headers
curl -I https://api.example.com/data
Upload a File
Send files via form data or multipart
curl -X POST \
-F "file=@/path/to/file.jpg" \
-F "description=My photo" \
https://api.example.com/upload
Set Timeout
Prevent hanging on slow connections
curl --connect-timeout 10 \
--max-time 30 \
https://api.example.com/data
Ignore SSL Errors
Skip certificate validation (use carefully!)
curl -k https://self-signed.example.com
# Or be more specific
curl --insecure https://self-signed.example.com
Save Cookies
Handle session cookies for authenticated flows
# Save cookies
curl -c cookies.txt https://example.com/login
# Use saved cookies
curl -b cookies.txt https://example.com/dashboard
Testing Different HTTP Methods
PUT Request
Update an existing resource
curl -X PUT \
-H "Content-Type: application/json" \
-d '{"name":"Updated Name"}' \
https://api.example.com/users/123
DELETE Request
Remove a resource
curl -X DELETE \
-H "Authorization: Bearer token" \
https://api.example.com/users/123
PATCH Request
Partial updates to a resource
curl -X PATCH \
-H "Content-Type: application/json" \
-d '{"email":"new@example.com"}' \
https://api.example.com/users/123
