How to check that the Apache compression (gzip, deflate) is working?

Use curl from the command line to check whether your Apache configuration compresses data before sending it to clients. Send Apache a request indicating that compressed responses are accepted, then inspect the returned headers to see how the data was sent. Example command to check Apache compression support:

[tum@ezylinux ~]$ curl -I -H 'Accept-Encoding: gzip,deflate' http://www.ezylinux.com |grep "Content-Encoding"

Replace http://www.ezylinux.com with the URL to check. If compression is supported, the response contains:

[...]
Content-Encoding: gzip
[...]

or

[...]
Content-Encoding: deflate
[...]

Example command and output:

[tum@ezylinux ~]$ curl -I -H 'Accept-Encoding: gzip,deflate' http://www.ezylinux.com |grep "Content-Encoding"
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0  8202    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
Content-Encoding: gzip