- The correct title of this article is fdupes. The initial letter is capitalized due to technical restrictions.
It searches the given path for duplicate files. Such files are found by comparing file sizes and MD5 signatures, followed by a byte-by-byte comparison. That is, it ignores filenames and locations; if the contents of the file are identical, it will find these files to be identical. It was written by Adrian Lopez.
- -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 non-duplicates; this option will change this behaviour
- -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 (see CAVEATS below)
- -v --version
- display fdupes version
- -h --help
- displays help
Unless -1 or --sameline is specified, duplicate files are listed together in groups, each file displayed on a separate line. The groups are then separated from each other by blank lines.
When -1 or --sameline is specified, spaces and backslash characters (\) appearing in a filename are preceded by a backslash character.
If fdupes returns with an error message such as fdupes: error invoking md5sum it means the program has been compiled to use an external program to calculate MD5 signatures (otherwise, fdupes uses interal routines for this purpose), and an error has occurred while attempting to execute it. If this is the case, the specified program should be properly installed prior to running fdupes.
When using -d or --delete, care should be taken to insure against accidental data loss.
When used together with options -s or --symlink, a user could accidentally preserve a symlink while deleting the file it points to.
Furthermore, when specifying a particular directory more than once, all files within that directory will be listed as their own duplicates, leading to data loss should a user preserve a file without its "duplicate" (the file itself!).