Linux / Unix Curl: Find Out If a Website Is Using Gzip / Deflate

Syntax

The syntax is:

curl -I -H 'Accept-Encoding: gzip,deflate' http://example.com

OR

curl -s -I -L -H 'Accept-Encoding: gzip,deflate' http://example.com

Where,

1. -s – Don’t show progress meter or error messages.
2. -I – Work on the HTTP-header only.
3. -H 'Accept-Encoding: gzip,deflate' – Send extra header in the request when sending HTTP to a server.
4. -L – f the server reports that the requested page has moved to a different location (indicated with a Location: header and a 3XX response code), this option will make curl redo the request on the new place.
5. http://example.com – Your URL, it can start with http or https.

Examples

Type the following command:

curl -I -H 'Accept-Encoding: gzip,deflate' http://www.cyberciti.biz/

Sample outputs:

HTTP/1.1 200 OK
Server: nginx
Date: Tue, 06 Nov 2012 18:59:26 GMT
Content-Type: text/html
Connection: keep-alive
X-Whom: l2-com-cyber
Vary: Cookie
Vary: Accept-Encoding
Last-Modified: Tue, 06 Nov 2012 18:51:58 GMT
Cache-Control: max-age=152, must-revalidate
Content-Encoding: gzip
X-Galaxy: Andromeda-1
X-Origin-Type: DynamicViaDAL

Curl command accept-encoding gzip bash test function

Create a bash shell function and add to your ~/.bashrc file:

gzipchk(){ curl -I -H 'Accept-Encoding: gzip,deflate' "$@" | grep --color 'Content-Encoding:'; }

OR use the silent mode to hide progress bar:

gzipchk(){ curl -sILH 'Accept-Encoding: gzip,deflate' "$@" | grep --color 'Content-Encoding:'; }

Save and close the file. Reload ~/.bashrc file, run:
$ source ~/.bashrc file
Test the gzipchk() as follows:
$ gzipchk www.cyberciti.biz
gzipchk http://www.redhat.com
Sample outputs:

Fig.01: Linux curl deflate gzip test in action