How do I properly set wget to download only new files?

Solution 1:

did you read this ? http://www.editcorp.com/Personal/Lars_Appel/wget/wget_5.html

"Several days later, you would like Wget to check if the remote file has changed, and download it if it has."

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

Try this.

Solution 2:

wget -c 

also continues partial files caused when the download has issues.....
Better yet,

 wget -c -N 

seems to do both at the same time.