Provided by: jdupes_1.14.0-2_amd64 
NAME
jdupes - finds and performs actions upon duplicate files
SYNOPSIS
jdupes [ options ] FILES and/or DIRECTORIES ...
DESCRIPTION
Searches the given path(s) for duplicate files. Such files are found by comparing file sizes, then
partial and full file hashes, followed by a byte-by-byte comparison. The default behavior with no other
"action options" specified (delete, summarize, link, dedupe, etc.) is to print sets of matching files.
OPTIONS
-@ --loud
output annoying low-level debug info while running
-0 --printnull
when printing matches, use null bytes instead of CR/LF bytes, just like 'find -print0' does. This
has no effect with any action mode other than the default "print matches" (delete, link, etc. will
still print normal line endings in the output.)
-1 --one-file-system
do not match files that are on different filesystems or devices
-A --nohidden
exclude hidden files from consideration
-B --dedupe
issue the btrfs same-extents ioctl to trigger a deduplication on disk. The program must be built
with btrfs support for this option to be available
-C --chunksize=BYTES
set the I/O chunk size manually; larger values may improve performance on rotating media by
reducing the number of head seeks required, but also increases memory usage and can reduce
performance in some cases
-D --debug
if this feature is compiled in, show debugging statistics and info at the end of program execution
-d --delete
prompt user for files to preserve, deleting all others (see CAVEATS below)
-f --omitfirst
omit the first file in each set of matches
-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
-h --help
displays help
-i --reverse
reverse (invert) the sort order of matches
-I --isolate
isolate each command-line parameter from one another; only match if the files are under different
parameter specifications
-L --linkhard
replace all duplicate files with hardlinks to the first file in each set of duplicates
-m --summarize
summarize duplicate file information
-M --printwithsummary
print matches and summarize the duplicate file information at the end
-N --noprompt
when used together with --delete, preserve the first file in each set of duplicates and delete the
others without prompting the user
-n --noempty
exclude zero-length files from consideration; this option is the default behavior and does nothing
(also see -z/--zeromatch)
-O --paramorder
parameter order preservation is more important than the chosen sort; this is particularly useful
with the -N option to ensure that automatic deletion behaves in a controllable way
-o --order=WORD
order files according to WORD: time - sort by modification time name - sort by filename (default)
-p --permissions
don't consider files with different owner/group or permission bits as duplicates
-P --print=type
print extra information to stdout; valid options are: early - matches that pass early
size/permission/link/etc. checks partial - files whose partial hashes match fullhash - files whose
full hashes match
-Q --quick
[WARNING: RISK OF DATA LOSS, SEE CAVEATS] skip byte-for-byte verification of duplicate pairs (use
hashes only)
-q --quiet
hide progress indicator
-R --recurse:
for each directory given after this option follow subdirectories encountered within (note the ':'
at the end of option; see the Examples section below for further explanation)
-r --recurse
for every directory given follow subdirectories encountered within
-l --linksoft
replace all duplicate files with symlinks to the first file in each set of duplicates
-S --size
show size of duplicate files
-s --symlinks
follow symlinked directories
-T --partial-only
[WARNING: EXTREME RISK OF DATA LOSS, SEE CAVEATS] match based on hash of first block of file data,
ignoring the rest
-v --version
display jdupes version and compilation feature flags
-x --xsize=[+]SIZE (NOTE: deprecated in favor of -X)
exclude files of size less than SIZE from consideration, or if SIZE is prefixed with a '+' i.e.
jdupes -x +226 [files] then exclude files larger than SIZE. Suffixes K/M/G can be used.
-X --extfilter=spec:info
exclude/filter files based on specified criteria; supported specs are:
`size[+-=]:number[suffix]'
Match only if size is greater (+), less than (-), or equal to (=) the specified number,
with an optional multiplier suffix. The +/- and = specifiers can be combined: "size+=:4K"
will match if size is greater than or equal to four kilobytes (4096 bytes). Suffixes
supported are K/M/G/T/P/E with a B or iB extension (all case-insensitive); no extension or
an iB extension specify binary multipliers while a B extension specifies decimal
multipliers (ex: 4K or 4KiB = 4096, 4KB = 4000.)
-z --zeromatch
consider zero-length files to be duplicates; this replaces the old default behavior when -n was
not specified
-Z --softabort
if the user aborts the program (as with CTRL-C) act on the matches that were found before the
abort was received. For example, if -L and -Z are specified, all matches found prior to the abort
will be hard linked. The default behavior without -Z is to abort without taking any actions.
NOTES
A set of arrows are used in hard linking to show what action was taken on each link candidate. These
arrows are as follows:
----> This file was successfully hard linked to the first file in the duplicate chain
-@@-> This file was successfully symlinked to the first file in the chain
-==-> This file was already a hard link to the first file in the chain
-//-> Linking this file failed due to an error during the linking process
Duplicate files are listed together in groups with each file displayed on a separate line. The groups are
then separated from each other by blank lines.
EXAMPLES
jdupes a --recurse: b
will follow subdirectories under b, but not those under a.
jdupes a --recurse b
will follow subdirectories under both a and b.
jdupes -O dir1 dir3 dir2
will always place 'dir1' results first in any match set (where relevant)
CAVEATS
Using -1 or --one-file-system prevents matches that cross filesystems, but a more relaxed form of this
option may be added that allows cross-matching for all filesystems that each parameter is present on.
When using -d or --delete, care should be taken to insure against accidental data loss.
-Z or --softabort used to be --hardabort in jdupes prior to v1.5 and had the opposite behavior.
Defaulting to taking action on abort is probably not what most users would expect. The decision to invert
rather than reassign to a different option was made because this feature was still fairly new at the time
of the change.
The -O or --paramorder option allows the user greater control over what appears in the first position of
a match set, specifically for keeping the -N option from deleting all but one file in a set in a
seemingly random way. All directories specified on the command line will be used as the sorting order of
result sets first, followed by the sorting algorithm set by the -o or --order option. This means that the
order of all match pairs for a single directory specification will retain the old sorting behavior even
if this option is specified.
When used together with options -s or --symlink, a user could accidentally preserve a symlink while
deleting the file it points to.
The -Q or --quick option only reads each file once, hashes it, and performs comparisons based solely on
the hashes. There is a small but significant risk of a hash collision which is the purpose of the
failsafe byte-for-byte comparison that this option explicitly bypasses. Do not use it on ANY data set for
which any amount of data loss is unacceptable. This option is not included in the help text for the
program due to its risky nature. You have been warned!
The -T or --partial-only option produces results based on a hash of the first block of file data in each
file, ignoring everything else in the file. Partial hash checks have always been an important exclusion
step in the jdupes algorithm, usually hashing the first 4096 bytes of data and allowing files that are
different at the start to be rejected early. In certain scenarios it may be a useful heuristic for a user
to see that a set of files has the same size and the same starting data, even if the remaining data does
not match; one example of this would be comparing files with data blocks that are damaged or missing such
as an incomplete file transfer or checking a data recovery against known-good copies to see what damaged
data can be deleted in favor of restoring the known-good copy. This option is meant to be used with
informational actions and can result in EXTREME DATA LOSS if used with options that delete files, create
hard links, or perform other destructive actions on data based on the matching output. Because of the
potential for massive data destruction, this option MUST BE SPECIFIED TWICE to take effect and will error
out if it is only specified once.
Using the -C or --chunksize option to override I/O chunk size can increase performance on rotating
storage media by reducing "head thrashing," reading larger amounts of data sequentially from each file.
This tunable size can have bad side effects; the default size maximizes algorithmic performance without
regard to the I/O characteristics of any given device and uses a modest amount of memory, but other
values may greatly increase memory usage or incur a lot more system call overhead. Try several different
values to see how they affect performance for your hardware and data set. This option does not affect
match results in any way, so even if it slows down the file matching process it will not hurt anything.
REPORTING BUGS
Send bug reports to jody@jodybruchon.com or use the issue tracker at: http://github.com/jbruchon/jdupes/issues
SUPPORTING DEVELOPMENT
If you find this program useful, please consider financially supporting its continued development by
visiting the following URL:
https://www.subscribestar.com/JodyBruchon
AUTHOR
jdupes is created and maintained by Jody Bruchon <jody@jodybruchon.com> and was forked from fdupes 1.51 by Adrian Lopez <adrian2@caribe.net>
LICENSE
The MIT License (MIT)
Copyright (C) 2015-2020 Jody Lee Bruchon and contributors Forked from fdupes 1.51, Copyright (C)
1999-2014 Adrian Lopez and contributors
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the
following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial
portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
THE USE OR OTHER DEALINGS IN THE SOFTWARE.
JDUPES(1)