Basic usage

• Download a URL to stdout:
  curl https://example.com

• Save output to a file:
  curl -o file.html https://example.com

• Save with remote filename:
  curl -O https://example.com/file.zip


HTTP methods

• GET (default):
  curl https://api.example.com/resource

• POST with form data:
  curl -d "name=alice&age=30" https://example.com/form

• POST JSON:
  curl -H "Content-Type: application/json" -d '{"key":"value"}' https://api.example.com/items

• PUT:
  curl -X PUT -d '{"name":"new"}' -H "Content-Type: application/json" https://api.example.com/items/1

• DELETE:
  curl -X DELETE https://api.example.com/items/1


Headers and authentication

• Add custom header:
  curl -H "Authorization: Bearer TOKEN" https://api.example.com

• Basic auth:
  curl -u username:password https://example.com/protected

• Send multiple headers:
  curl -H "Accept: application/json" -H "X-Api-Version: 2" https://api.example.com


Files and uploads

• Upload a file with multipart/form-data:
  curl -F "file=@/path/to/file.jpg" https://example.com/upload

• Upload raw data from file:
  curl --data-binary @local.bin https://example.com/put


Follow redirects, show headers, verbose

• Follow redirects:
  curl -L http://short.url

• Show response headers:
  curl -i https://example.com

• Show only headers:
  curl -I https://example.com

• Verbose for debugging:
  curl -v https://example.com


Timeouts, retries, rate

• Set max time:
  curl --max-time 30 https://example.com

• Retry on transient errors:
  curl --retry 5 https://example.com


Cookies and sessions

• Save cookies to file:
  curl -c cookies.txt -L https://example.com/login

• Send cookies from file:
  curl -b cookies.txt https://example.com/dashboard


Scripting and output control

• Silent mode (no progress):
  curl -s https://example.com

• Silent but show errors:
  curl -sS https://example.com

• Show HTTP status code only:
  curl -o /dev/null -s -w "%{http_code}\n" https://example.com


Examples

• GET JSON and pretty-print (using jq):
  curl -s https://api.example.com/data | jq .

• POST JSON with header:
  curl -s -H "Content-Type: application/json" -d '{"title":"Hi"}' https://api.example.com/posts

• Download multiple files listed in urls.txt:
  xargs -n1 -P4 curl -O < urls.txt


Check version and help

• Version:
  curl --version

• Full help:
  curl --help