Artem Russakovskii's programming and technology blog

Updated: July 21st, 2020

Today, I was looking for a quick way to see HTTP response codes of a bunch of urls. Naturally, I turned to the curl command, which I would usually use like this:

curl -IL "URL"

This command would send a HEAD request (-I), follow through all redirects (-L), and display some useful information in the end. Most of the time it's ideal:

curl -IL "http://www.google.com"
 
HTTP/1.1 200 OK
Date: Fri, 11 Jun 2010 03:58:55 GMT
Expires: -1
Cache-Control: private, max-age=0
Content-Type: text/html; charset=ISO-8859-1
Server: gws
X-XSS-Protection: 1; mode=block
Transfer-Encoding: chunked

However, the server I was curling didn't support HEAD requests explicitly. Additionally, I was really only interested in HTTP status codes and not in the rest of the output. This means I would have to change my strategy and issue GET requests, ignoring HTML output completely.

Curl manual to the rescue. A few minutes later, I came up with the following, which served my needs perfectly:

curl -sL -w "%{http_code} %{url_effective}\\n" "URL" -o /dev/null

Here is a sample of what comes out:

curl -sL -w "%{http_code} %{url_effective}\\n" "http://www.amazon.com/Kindle-Wireless-Reading-Display-Generation/dp/B0015T963C?tag=androidpolice-20" -o /dev/null
 
200 http://www.amazon.com/Kindle-Wireless-Reading-Display-Generation/dp/B0015T963C

Here, -s silences curl's progress output, -L follows all redirects as before, -w prints the report using a custom format, and -o redirects curl's HTML output to /dev/null.

Here are the other special variables available in case you want to customize the output some more:

• url_effective
• http_code
• http_connect
• time_total
• time_namelookup
• time_connect
• time_pretransfer
• time_redirect
• time_starttransfer
• size_download
• size_upload
• size_header
• size_request
• speed_download
• speed_upload
• content_type
• num_connects
• num_redirects
• ftp_entry_path

Is there a better way to do this with curl? Perhaps, but this way offers the most flexibility, as I am in control of all the formatting.