Find all duplicate files by MD5 hash

From "man xargs": -I implies -L 1 So this is not most efficient. It would be more efficient, if you just give as many filenames to md5sum as possible, which would be:

find . -type f -print0 | xargs -0 md5sum | sort | uniq -w32 --all-repeated=separate

Then you won't have the file size of course. If you really need the file size, create a shell script, which does the md5sum and du -h and merge the lines with join.