fdupes is a tool for identifying duplicate files across a set of directories. It works by scanning the specified directories for files, running md5sum on those files, then running a byte-by-btye comparison on the files. It can work in tandem with duperemove, a deduplication tool for btrfs.
emerge --ask app-misc/fdupes
fdupes has no configuration options other than optional command-line parameters.
Usage: fdupes [options] DIRECTORY... -r --recurse for every directory given follow subdirectories encountered within -R --recurse: for each directory given after this option follow subdirectories encountered within -s --symlinks follow symlinks -H --hardlinks normally, when two or more files point to the same disk area they are treated as non-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 -m --summarize summarize dupe information -q --quiet hide progress indicator -d --delete prompt user for files to preserve and delete all others; important: under particular circumstances, data may be lost when using this option together with -s or --symlinks, or when specifying a particular directory more than once; refer to the fdupes documentation for additional information -N --noprompt together with --delete, preserve the first file in each set of duplicates and delete the rest without prompting the user -v --version display fdupes version -h --help display this help message
Find duplicate files recursively
To find duplicate files in target directories recursively the following command could be used:
fdupes --recurse --size /path/to/dir/one /path/to/dir/two
Permissions problems may occur when some files are owned by root or another user; in this case users should run the fdupes command again with appropriate privileges.
Most of the time, however, it is wise to redirect the output of the fdupes command to a file:
fdupes --recurse --size /path/to/dir/one /path/to/dir/two >> /tmp/fdupes_file_list.txt
Creating a file is a wise and efficient idea, especially when a large amount of files are being compared. It is much easier to look through a large file list with a text editor rather than attempting to parse the list via scroll back in a terminal buffer.
Find and delete files recursively
Users are strongly cautioned to run one of the above command(s) before running one of the next commands. This is done in order to verify the output is as expected. Do the operation right the first time; the fewer mistakes the better! After output is satisfactory, the following command can be used to delete all but the first occurrence of the file. Be sure to list the directories in the order of precedence so that the correct files are preserved. I.e. to keep all the files in home directory, listing the home directory last will make it show up first in the list.
The following command uses the
-d) options to delete all but the first duplicate found in a file list (created using a previous command) without prompting the user:
fdupes --noprompt --delete --recurse /path/to/dir/one /path/to/dir/two
No special files need to removed. Uninstall fdupes via:
emerge --ask --depclean --verbose app-misc/fdupes