First install fdupes
sudo apt-get install fdupesNow 'cd' into your directory.
To make a summary of how much space you can save by deleting duplicate files, execute the following:
fdupes -r -m ./To really delete the duplicate files:
fdupes -r -d -N ./-N means no prompt (deleting wihout asking anything)
-d means delete
-r means recurse into all subdirectories
without any flag fdupes will print, for each duplicated file, its duplicates, for all files that have duplicates