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Installing cURL#

To invoke the REST Web Services described in this workshop, we often use cURL.1 cURL is a command-line tool and library to do reliable data transfers with various protocols, including HTTP. It is free, open-source (available under the MIT Licence), and has been ported to several operating systems. If your operating system does not already include cURL (most do), here is how to install it.

Installing cURL#

If you are on Mac OS X and have installed Homebrew, then installing cURL is just a matter of a single command.2 Open your terminal and install cURL with the following command:

brew install curl

For Windows, download and install curl from the official website.

Checking for cURL Installation#

Once installed, check for cURL by running curl –version in the terminal. It should display cURL version:

$ curl --version
curl 7.64.1 (x86_64-apple-darwin20.0) libcurl/7.64.1 (SecureTransport) LibreSSL/2.8.3 zlib/1.2.11 nghttp2/1.41.0
Release-Date: 2019-03-27
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtsp smb smbs smtp smtps telnet tftp
Features: AsynchDNS GSS-API HTTP2 HTTPS-proxy IPv6 Kerberos Largefile libz MultiSSL NTLM NTLM_WB SPNEGO SSL UnixSockets

Some cURL Commands#

cURL is a command-line utility where you can use several parameters and options to invoke URLs. You invoke curl with zero, one, or several command-line options to accompany the URL (or set of URLs) you want the transfer to be about. cURL supports over two hundred different options, and I would recommend reading the documentation for more help3. To get some help on the commands and options, you can type, use the following command:

$ curl --help

You can also opt to use curl --manual, which will output the entire man page for cURL plus an appended tutorial for the most common use cases.

Here are some commands you will use to invoke RESTful web services.

  • curl http://localhost:8083/api/heroes/hello: HTTP GET on a given URL.
  • curl -X GET http://localhost:8083/api/heroes/hello: Same effect as the previous command, an HTTP GET on a given URL.
  • curl -v http://localhost:8083/api/heroes/hello: HTTP GET on a given URL with verbose mode on.
  • curl -H 'Content-Type: application/json' http://localhost:8083/api/heroes/hello: HTTP GET on a given URL passing the JSON Content Type in the HTTP Header.
  • curl -X DELETE http://localhost:8083/api/heroes/1: HTTP DELETE on a given URL.

References#

  1. cURL ↩

  2. Installing cURL on Mac OS X ↩

  3. cURL commands ↩