How to download only changed file with curl or wget?

Question

Python

Hello!
I need to download archives from a repository (eg https://downloads.wordpress.org/plugin/disable-com... only when the file on the server has a different size (Content-Length). The script is written in
Python.downloads. wordpress.org gives all the necessary data to find out when the file was modified and its size:

Status: HTTP/1.1 200 OK
Server:	nginx	
Date:	Mon, 15 Aug 2016 06:30:46 GMT	
Content-Type:	application/zip	
Content-Length:	80828	
Connection:	close	
Cache-control:	private	
Content-Disposition:	attachment; filename=disable-comments.zip	
Last-Modified:	Fri, 12 Aug 2016 09:46:22 GMT	
X-Frame-Options:	SAMEORIGIN	
X-nc:	BYPASS lax 189	
Accept-Ranges:	bytes

Tried wget, aria2c , curl with python os library: such a file already exists in the local directory. (I use the -N key for wget)
2. C curl does not work for me at all. It stupidly downloads the file and overwrites (curl url --output /folder/1.zip).
It seems to me that I am using the capabilities of these utilities incorrectly. Is it possible to implement such a task with python libraries without calling os?
Please help me figure this out. Thanks in advance.
PS I would like to solve the problem with wget, curl, so that they do not download the actual file on the local.

Answer 1

Well, there are many options.
As far as Python is concerned, here is an example algorithm for solving your problem:
1) Take the requests module (for simplicity)
2) request headers for your file through it (r = requests.head(' example.com '))
3) Compare content- length with the size of your file
4) If different, download the file
5) ...
6) Profit
PS: Wget and Curl also support getting only headers
for wget - this is the "--server-response"
parameter for curl - this is the '-head parameter '