Important curl command flags

REST APIs are essential for modern web applications, enabling programmatic interaction with data and functionality. Curl is a command-line tool for making web requests, often used directly from the terminal. For example, curl -L ip.ba3a.tech fetches IP address details in JSON format, just like visiting the site in a browser. Essentially, Curl prints the web response to the terminal. In this article, we will learn how to make REST API requests using Curl.

For the sake of this article, let’s use a sample social media API that I have created. This will help demonstrate how to make REST API requests using cURL.

Example 1: Create (POST) Request

In this example, we use curl to send a POST request to the endpoint https://crud.ba3a.tech/users to create a new user. The -X POST flag specifies the request method, -H “Content-Type: application/json” sets the content type header, and -d ‘{“name”: “Ba3a”, “email”: “someMail@gmail.com”}’ sends the user data in JSON format.

Command:

#!/bin/bash

curl -X POST \
  -H "Content-Type: application/json" \
  -d '{"name": "Ba3a", "email": "someMail@gmail.com"}' \
  https://crud.ba3a.tech/users

Explanation:

• -X POST: Specifies the HTTP method for creating a new resource.
• -H “Content-Type: application/json”: Sets the content type header to indicate JSON data is being sent.
• -d ‘{“name”: “Ruchi”, “email”: “someMail@gmail.com”}’: Includes the user data in JSON format using the -d flag.

Output:

Example 2: Read (GET) Request

In this example, we use curl to send a GET request to the endpoint https://crud.ba3a.tech/users/1 that fetches user data based on the user-id i.e. 1.

Command:

curl https://crud.ba3a.tech/users/1

Explanation:

• curl: Command-line tool for transferring data using various network protocols. In this context, it’s used to make an HTTP GET request.
• https://crud.ba3a.tech/users/1: The URL to which the GET request is sent.

Output:

Example 3: Update (PUT) Request

In this example, we use curl to send a PUT request to the endpoint https://crud.ba3a.tech/users/3 to update the user. The -X PUT flag specifies the request method, -H “Content-Type: application/json” sets the content type header, and -d ‘{“email”: “updated.email@example.com”}’ sends the user data in JSON format.

Command:

#!/bin/bash

curl -X PUT \
  -H "Content-Type: application/json" \
  -d '{"email": "updated.email@example.com"}' \
  https://crud.ba3a.tech/users/3

Explanation:

• curl: This is the command-line tool used to transfer data with URLs.
• -X PUT: Specifies the HTTP method to use, in this case, PUT, which is used to update a resource on the server.
• -H "Content-Type: application/json": Sets the Content-Type header to application/json, indicating the data format being sent.
• -d '{"email": "updated.email@example.com"}': Specifies the data to be sent in the request body. Here, it is a JSON object updating the email field.
• https://crud.ba3a.tech/users/3: The URL endpoint for the API request.

Output:

Example 4: Delete (DELETE) Request

In this example, we use curl to send a DELETE request to the endpoint https://crud.ba3a.tech/users/3 to delete the user with ID 3. The -X DELETE flag specifies the request method.

Command:

curl -X DELETE https://crud.ba3a.tech/users/3

Explanation:

• curl: This is the command-line tool used to transfer data with URLs.
• -X DELETE: Specifies the HTTP method to use, in this case, DELETE, which is used to remove a resource on the server.
• https://crud.ba3a.tech/users/3: The URL endpoint for the API request.

Output:

Now that we know how to make REST API requests with CURL, let us see some important flags that might be useful.