Ant - Copy Files That Have Changed

If you want to copy files that have changed from one directory to another use a file set with the "modified" option like this:

 <copy todir="${dir.copy.to}">
  <fileset dir="${dir.copy.from}">
         <modified/>
        </fileset>
        
 </copy>

Ant will set up a cache.properties file which tracks file information so it knows the state of files after each build. Then when it runs a task it can refer to the cache file to determine which files have changed since the last successful build and need to be included in the fileset.

If you want the build to include a file that is getting excluded by the cache file just delete that file from the cache.properties file and it will be included in the file set the next time the ant build is run.