cURL basics

cURL is a command line tool for interacting with servers, it can be used in bash scripts to automate some workflows. This post covers primary usage with examples.

• Send an HTTP GET request to the server

curl ipv4.icanhazip.com

• Get only the response headers

curl -I ipv4.icanhazip.com

• Send POST requests with the request body and headers

curl -X POST https://api.gumroad.com/v2/licenses/verify \
  -d "product_id=product-id" \
  -d "license_key=license-key"

curl https://api.openai.com/v1/chat/completions \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-3.5-turbo",
    "messages": [{"role": "user", "content": "What is cURL?"}]
  }'

• Use the i option to include the headers in the response

curl -i -X POST https://api.gumroad.com/v2/licenses/verify \
  -d "product_id=product-id" \
  -d "license_key=license-key"

• Use the s option to hide all the logs during the request

curl -s -X POST https://api.gumroad.com/v2/licenses/verify \
  -d "product_id=product-id" \
  -d "license_key=license-key"

• Use the v option for verbose logs during the request

curl -v -X POST https://api.gumroad.com/v2/licenses/verify \
  -d "product_id=product-id" \
  -d "license_key=license-key"

• Retrieve bash script and run it locally

curl https://raw.githubusercontent.com/creationix/nvm/master/install.sh | bash

• Trigger specific endpoint inside Kubernetes cronjob

# ...
containers:
  - name: cleanup
    # ...
    command:
      - /bin/sh
      - -ec
      - 'curl "https://some-service.com/cleanup"'