wget with 304 check

Question

Is it possible to use wget to download a file, if only it's not modified?

I'm thinking about the HTTP status code 304, but I don't know how to instruct wget to add a If-Modified-Since header, or something similar.

Is it even possible? I can use other tools to do that as well

Answer 1

You may wish to read this, http://www.editcorp.com/Personal/Lars_Appel/wget/wget_5.html

Basically, it's :

wget -N http://www.some-url.com/folder/

Answer 2

If you want to add a header, you can use the --header option:

wget --header="If-Modified-Since: …" http://example.com/

But for the specific case in the question, it’s better to do as the other answer here suggests: Just use the -N option.