Perl dedupe script. http://unix.stackexchange.com/a/42195

gistfile1.txt

#!/bin/bash

DIR="/path/to/big/files"

find $DIR -type f -exec md5sum {} \; | sort > /tmp/sums-sorted.txt

OLDSUM=""
IFS=$'\n'
for i in `cat /tmp/sums-sorted.txt`; do
 NEWSUM=`echo "$i" | sed 's/ .*//'`
 NEWFILE=`echo "$i" | sed 's/^[^ ]* *//'`
 if [ "$OLDSUM" == "$NEWSUM" ]; then
  echo ln -f "$OLDFILE" "$NEWFILE"
 else
  OLDSUM="$NEWSUM"
  OLDFILE="$NEWFILE"
 fi
done