Finding duplicate files
$ find . -type f -print0 |
xargs -0 md5sum > MD5SUMS
$ sort < MD5SUMS | uniq -D -w 32 > DUPLICATES
…or the complicated way…
$ find . -type f -print0 |
xargs -0 md5sum > MD5SUMS
$ sort < MD5SUMS | cut -d\ -f1 | uniq -D |
xargs -n1 -i grep {} MD5SUMS > DUPLICATES