command line - Unzip only updated files

Is there a way to unzip a zip file into a directory, but only do so for updates files (I mean the compressed files inside the zip)? I have a huge directory of files there, and only about 20% are different.

Preferably using command line, but it's optional. I use Windows XP.

Thanks.

Answer

With the winzip commandline addon, you can use the -n option:

-n

Unzip only newer files. This option updates existing files if the archived file is newer and creates new ones if they do not already exist.

wzunzip -n "c:\my documents\spring2007.zip" c:\semesters\spring05  

This example will extract, from c:\my documents\spring2007.zip, ONLY those files that are newer than the files that currently exist in c:\semesters\spring05 OR that do not already exist in the c:\semesters\spring05 folder.

You might want to combine it with the -o option - "Overwrite existing files without a prompt (automatically reply "Yes" to each overwrite prompt)."