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!

Recent Features

  • By
    Write Better JavaScript with Promises

    You've probably heard the talk around the water cooler about how promises are the future. All of the cool kids are using them, but you don't see what makes them so special. Can't you just use a callback? What's the big deal? In this article, we'll...

  • By
    Vibration API

    Many of the new APIs provided to us by browser vendors are more targeted toward the mobile user than the desktop user.  One of those simple APIs the Vibration API.  The Vibration API allows developers to direct the device, using JavaScript, to vibrate in...

Incredible Demos

  • By
    MooTools Image Preloading with Progress Bar

    The idea of image preloading has been around since the dawn of the internet. When we didn't have all the fancy stuff we use now, we were forced to use ugly mouseover images to show dynamism. I don't think you were declared an official...

  • By
    Drag and Drop MooTools File Uploads

    Honesty hour confession:  file uploading within the web browser sucks.  It just does.  Like the ugly SELECT element, the file input is almost unstylable and looks different on different platforms.  Add to those criticism the fact that we're all used to drag and drop operations...

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.

  5. Shyam Chathuranga

    Connection header is set to closed, however when checking via Firebug or other tools such as Pingdom shows Keep-alive. Do you know why is that so?

    Thank you,
    Shyam

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