How to Find duplicate copies of files Using fdupes

FDupes uses md5sums and then a byte by byte comparison to find
duplicate files within a set of directories. It has several useful options
including recursion.
Install fdupes in ubuntu
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sudo aptitude install fdupes
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This will install all the required packages for fdupes
Using fdupes

Fdupes syntax
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-r --recurse - include files residing in subdirectories
-s --symlinks - follow symlinked directories
-H --hardlinks - normally, when two or more files point to the same disk area they are treated as nonn-duplicates; this
option will change this behavior
-n --noempty - exclude zero-length files from consideration
-f --omitfirst - omit the first file in each set of matches
-1 --sameline - list each set of matches on a single line

-S --size - show size of duplicate files
-q --quiet - hide progress indicator
-d --delete - prompt user for files to preserve, deleting all others
-v --version - display fdupes version
-h --help - displays help
Fdupes Examples
1) fdupes -r ./stuff > dupes.txt
Then, deleting the duplicates was as easy as checking dupes.txt and deleting the offending directories. fdupes also can prompt
you to delete the duplicates as you go along.
2) fdupes -r /home/user > /home/user/duplicate.txt
Output of the command goes in duplicate.txt
fdupes will compare the size and M D5 hash of the files to find duplicates

Reference
http://www.ubuntugeek.com/