gistfile1.txt

-> % http -p Hh  http://localhost:8123/ "If-Modified-Since: Thu, 07 Jan 2016 11:42:12 GMT"
GET / HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Host: localhost:8123
If-Modified-Since:  Thu, 07 Jan 2016 11:42:12 GMT
User-Agent: HTTPie/0.9.2

HTTP/1.1 200 OK
Connection: keep-alive
Content-Encoding: gzip
Content-Type: text/html
Date: Thu, 07 Jan 2016 12:46:26 GMT
Last-Modified: Thu, 07 Jan 2016 11:42:13 GMT
Server: nginx/1.4.6 (Ubuntu)
Transfer-Encoding: chunked

###############################

-> % http -p Hh  http://localhost:8123/ "If-Modified-Since: Thu, 07 Jan 2016 11:42:13 GMT"
GET / HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Host: localhost:8123
If-Modified-Since:  Thu, 07 Jan 2016 11:42:13 GMT
User-Agent: HTTPie/0.9.2

HTTP/1.1 304 Not Modified
Connection: keep-alive
Date: Thu, 07 Jan 2016 12:46:29 GMT
ETag: "568e4f15-264"
Last-Modified: Thu, 07 Jan 2016 11:42:13 GMT
Server: nginx/1.4.6 (Ubuntu)

###############################

-> % http -p Hh  http://localhost:8123/ "If-Modified-Since: Thu, 07 Jan 2016 11:42:14 GMT"
GET / HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Host: localhost:8123
If-Modified-Since:  Thu, 07 Jan 2016 11:42:14 GMT
User-Agent: HTTPie/0.9.2

HTTP/1.1 200 OK
Connection: keep-alive
Content-Encoding: gzip
Content-Type: text/html
Date: Thu, 07 Jan 2016 12:47:12 GMT
Last-Modified: Thu, 07 Jan 2016 11:42:13 GMT
Server: nginx/1.4.6 (Ubuntu)
Transfer-Encoding: chunked