HTTP.

Command line tools for HTTP protocol.

http://daniel.haxx.se/docs/curl-vs-wget.html

Comparing curl and wget.

Recursive site download.

curl does not allow recursive site downloading, only wget can do this:

$ wget -r -np -nc -e robots=off -p -k http://DOMAIN/PATH

Get server response header.

$ wget --server-response http://example.com
$ wget -S http://example.com    # short variant

$ curl --dump-header - http://example.com
$ curl -D - http://example.com

View cookies from site.

$ wget --save-cookies FILE -O -  http://example.com  >/dev/null
$ curl --cookie-jar FILE -o - http://example.com  >/dev/null
$ curl -c FILE -o - http://example.com  >/dev/null

Send cookies to site.

$ wget --load-cookies FILE  http://example.com
$ curl --cookie $name=$data  http://example.com
$ curl -b $name=$data  http://example.com

Send specific header line.

$ wget --header='Accept-Charset: iso-8859-2' --header='Accept-Language: ru' http://example.com
$ curl --header 'Accept-Charset: iso-8859-2' http://example.com
$ curl -H 'Accept-Charset: iso-8859-2' http://example.com

Send POST request.

Log in to the server. This can be done only once:

$ wget --save-cookies cookies.txt --post-data 'user=foo&password=bar' http://server.com/auth.php

Now grab the page or pages we care about:

$ wget --load-cookies cookies.txt -p http://server.com/interesting/article.php

Web server in Cygwin.

$ setup -p apache2,lighttpd,dhttp

Compressing HTTP data.

Starting with HTTP/1.1, web clients can indicate support for compression:

Accept-Encoding: gzip, deflate

Web server notifies the web client of this via the Content-Encoding header in the response:

Content-Encoding: gzip

ETags.

Server respond:

HTTP/1.1 200 OK
Last-Modified: Tue, 12 Dec 2006 03:03:59 GMT
ETag: "10c24bc-4ab-457e1c1f"
Content-Length: 12195

Lately client send:

GET /i/yahoo.gif HTTP/1.1
Host: us.yimg.com
If-Modified-Since: Tue, 12 Dec 2006 03:03:59 GMT
If-None-Match: "10c24bc-4ab-457e1c1f"

and get respond:

HTTP/1.1 304 Not Modified