Retrieve Headers with cURL

By  on  

We all know the cURL is incredibly useful.  We can retrieve remote content with curl, post to a remote URL, and perform hundreds of other tasks.  One simple task that can be completed is simply retrieving basic response headers.  To test the robot indexing prevention header I added to the Mozilla Developer Network, I used one simple cURL command to grab all headers from an address.

The Shell

The cURL command is short and sweet:

curl -I davidwalsh.name

Said command provides a list that looks similar to:

HTTP/1.1 200 OK
Date: Fri, 14 Sep 2012 21:51:17 GMT
Server: Apache/2.2.3 (CentOS)
Last-Modified: Fri, 14 Sep 2012 21:51:00 GMT
Accept-Ranges: bytes
Content-Length: 10910
Cache-Control: max-age=1, private, must-revalidate
Expires: Fri, 14 Sep 2012 22:51:00 GMT
Vary: Accept-Encoding,Cookie
X-Powered-By: W3 Total Cache/0.9.2.4
X-Pingback: https://davidwalsh.name/xmlrpc.php
Pragma: public
Connection: close
Content-Type: text/html; charset=UTF-8

This command is helpful when ensuring a given header has been correctly set within your programming, as well as seeing where a given short URL may redirect to:

$ curl -I bit.ly/Q8f9o

HTTP/1.1 301 Moved
Server: nginx
Date: Fri, 14 Sep 2012 21:53:14 GMT
Content-Type: text/html; charset=utf-8
Connection: keep-alive
Set-Cookie: _bit=5053a74a-0011d-0688d-311cf10a;domain=.bit.ly;expires=Wed Mar 13 21:53:14 2013;path=/; HttpOnly
Cache-control: private; max-age=90
Location: https://davidwalsh.name/
MIME-Version: 1.0
Content-Length: 115

It's also useful to see the server name, expires information and more.  I also appreciate that it's a clean list and no other information is pushed into the response.  If you get some time, cURL out to different popular domains and see what headers they send -- you could be surprised!

Raygun Pulse

Recent Features

  • By
    fetch API

    One of the worst kept secrets about AJAX on the web is that the underlying API for it, XMLHttpRequest, wasn't really made for what we've been using it for.  We've done well to create elegant APIs around XHR but we know we can do better.  Our effort to...

  • By
    Regular Expressions for the Rest of Us

    Sooner or later you'll run across a regular expression. With their cryptic syntax, confusing documentation and massive learning curve, most developers settle for copying and pasting them from StackOverflow and hoping they work. But what if you could decode regular expressions and harness their power? In...

Incredible Demos

  • By
    MooTools Window Object Dumping

    Ever want to see all of the information stored within the window property of your browser? Here's your chance. The XHTML We need a wrapper DIV that we'll consider a console. The CSS I like making this look like a command-line console. The MooTools JavaScript Depending on what you have loaded...

  • By
    jQuery Countdown Plugin

    You've probably been to sites like RapidShare and MegaUpload that allow you to download files but make you wait a specified number of seconds before giving you the download link. I've created a similar script but my script allows you to animate the CSS font-size...

Discussion

  1. Thanks for this great tips for cURL.
    I did not know before that i can get header with cURL

  2. Alex

    I’m using Charles (on desktop), it can show both the request and response headers. Handy even when not trying to cheat for water on farmville 2 :P

    I highly recommend it to other devs as it has many cool features (such as throttling, charts and request/response manipulation).

  3. That’s a useful tip – thanks! I’ve always done lynx -head dump but that’s a lot quicker and easier.

    One thing to be aware of is that it makes a HEAD request. I would think it normally will return the same header values as a GET or POST but still something worth thinking about depending what you are using it for.

  4. iamzesh

    It’s important to note that some servers are set to respond differently to HEADER requests than to GET requests. For example, a HEADER request returns a 200 OK while a GET request returns a 301 Moved Permanently… It can be quite confusing and unreliable depending on what you’re testing.

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!