I have checked syntax..it is not throwing any error but still downloading a 0 byte file

HI, I have been using cURL commands in CQ5.6 to upload & download packages. Now I am trying to use them in AEM6 and download command doesnt work.I have executed the below commandcurl -u admin:adm!nn0wn http://localhost:4508/etc/packages/my_packages/xxxx.zip > xxxx.zipand it just returns a 0 byte fil...