FREEDUP                allows you to reclaim space on your drives. It's simple.

Introduction Syntax Download Examples Hints How it Works Feedback Preview

Freedup walks through the file trees (directories) you specify.
When it finds two identical files on the same device, it hard links them together.
In this case two or more files still exist in their respective directories,
but only one copy of the data is stored on disk; both directory entries point to the same data blocks.

FREEDUP IN ACTION

If both files reside on different devices, then they are symlinked together.
Please see the Syntax page for instructions, how to modify the bahaviour of freedup.

Syntax Of FREEDUP

freedup[options] [<tree> ...]
Options are toggle switches. Their final state applies.
Later <tree> entries are linked to the earlier ones.
Providing no <tree> means to take filenames(!) from stdin.
When standard input is used the option -o has no effect.
FreeDup Version 1.5-3 by AN@freedup.org ©2007-2009.
Sha1 Version 1.0.4 by Allan Saddi ©2001-2003.
 
 

Option Categories

File Comparison
-aprovide compatibility to freedups by William Stearns.[=-gup]
-drequires the modification time stamps to be equal.
-D <sec>allow the modification time stamps to differ by not more than <sec> seconds.
-frequires the path-stripped file names to be equal.
-grequires groups to be equal.
-prequires file permissions to be equal.
-P <mask> set permission <mask> to an octal number, which indicates the permissions that need to be identical when comparing files.
-urequires users to be equal.
 
Comparison Style
-x <style>where style means what kind of containers freedup should look for before processing, i.e. the calculation of hashsums and comparison.
mp3 ignores mp3v1 and mp3v2 tags
mp4 ignores all mpeg containers except the first sequence of mdat ones
mpc ignores mouse pack trailing tags
jpg ignores jpeg header tags (including quantizazion)
ogg ignores OggS header and short trailing tags
auto selects one of above methods when appropriate
 
Hash Functions
-t <type> selects an external hash method. Valid choices are sha512, sha384, sha256, sha224, sha1, md5, sum . External hash functions are not supported with comparison styles.
-# <level>with level one of 0, 1, or 2. Controls the way that hash functions are used. Independently all files are compared byte by byte. Default is 2, which results in a fast hash function calculation during byte-by-byte comparision. This needs some more memory and the same or less time than level 0, which does not evaluate any hash values. Level 1 is needed to evaluate hash functions before comparing a pair of files. External hash functions require level 1 (higher levels are lowered automatically). A side effect of level 0 is to disable external hash functions.
 
Reporting
-ccount file space savings per linked file.
-hshows this help and the long option names. [other option are ignored]
-Hshows all identical files whether already linked or not. Use it with -n.
-qproduces no output during the run (also toggles -c and -v to off)
-vdisplay shell commands to perform linking [verbose].
 
Actions
-lonly allow hardlinks. No symlinks are established.
-ndo not really perform links [no action].
-sgenerate symlinks although some given paths are relative.
-wonly weak symbolic links allthough hardlinks might be possible.
-Twhen linking, keep the directories' modification and access time.
-0disable linking of empty files i.e. files of size 0.
 
Link Directions
-k <key>Use key to define link direction, where key is one of ...
@  link all identical files to the one which has already the most links.
#  link all identical files to the first one that occured on commandline.
<  link all identical files to the oldest one in the set.
>  link all identical files to the newest one in the set.
-  link all to the smallest one when using extra styles (like < otherwise).
+  link all to the biggest one when using extra styles (like > otherwise).
else  link identical files arbitrarily (to first in unsorted list).
You should pay attention on masking these characters like '#' or \#
 
General Behaviour
-b <path>set current working directory to the given path.
-e <env>load an environment set, i.e. some stored default settings. If not present, it will be stored. Please note, that the environment setting are loaded at its position in the command line, but stored after all settings were performed. Only the directories from the command line will be stored.
-idecide in interactve mode what to do with identical files.
-m <bytes>only touch larger files. (deprecated: use -o -size +#c)
-o <opts>pass one option string to the initially called find command (last given string applies). If not given an interal function is called instead of find.
<tree>any directory tree to scan for duplicate files recursively.
 

Download

Starting with version 1.0-4 the packages on this page are signed.

If you are using versions not listed here, I strongly recommended to upgrade to the current version. Cygwin releases of version 0 do not have a correct working comparison engine. Due to this (former) defiences you might want to compare it to other programs, i.e. at Wikipedia.org/wiki/freedup.

How freedup in principle works

There are neither warranties nor guarantees for freedup working correctly. In principle freedup only knows about linking. Therefore the maximum risk is to link different files. During development many precautions were taken, but I have to emphasize that this risk exists. Only when using interactive mode you may delete files in a two step process, too. If you detect any possible source of misbehaviour in freedup, please report it for the sake of all users.

In principle freedup always searches for files of identical size and compares them byte-by-byte. The only exception are "extra styles", where the tags (details see next chapter) are intentionally skipped. Before files are compared byte-by-byte you might apply restrictions, like being owned by the same group or user, having the same permission or whatever the options allow you. Files that match in content and fulfil all required prerequisites are linked in the demanded way.

  1. Scan all directory trees recursively for all regular files.
  2. Build a sequential list of those files and keep their name.
  3. The arg position or pipe input sequence is kept by adding sequence numbers th each file.
  4. Use lstat() on each file to read and store its size with the filename.
  5. Sort the file and its attached information by comparing their sizes using qsort().
  6. In case the comparison has to report equal file size additional properties are compared.
  7. Most of those property checks are switched off by default.
  8. If all demands are fullfilled, the files are compared block by block (4k).
  9. If both files are identical and on the same file system they are added to link list.
  10. The link list will not be processed before all comparisons are complete.
  11. After all files are compared freedup starts processing the link list.
  12. For each link list entry, i.e. a set of identical files, the requested order is prepared.
  13. In interactive mode the files are now presented to make your file specific choice.
  14. The files that are intended to be linked, will be renamed, hard linked, renamed file removed.
  15. If hardlinking is not possible soft links are tried, except one of the paths is not starting at root (but can be forced)
  16. Finally a short report is delivered.

For more details please have a look into the source code or ask the author.

How freedup "extra styles" work

This concept was introduced in version 1.1 due to the fact that I wanted files to be linked although they differed. I am talking of mp3 files where the tags showed minor variations. First I considered retagging all files, but I would have to remove either all or complete all tags (n.b. MP3v1 tags are at the end, MP3v2 tags are at the beginning of an mp3 file, both are optional).

The extra style now should compare the essential file content, i.e. the mpeg encoded sound part in case of the mp3 files. Currently the following rules are established:

since for each file type exactly one method exists (might change in future), an automated mode will call the respective method according to the file magic. The name of each file is not considered for type checking.

Please note, that these styles change the behaviour according to the file contents. The change the size of the compared contents, but this does not affect the options that belong to the files, like ownerships or file names.

If you like to contribute, this is quite simple. There are source files for each style. Start with a copy of my.c and my.h. Rename the functions, fill in your way to evaluate the irrelevant bytes at start and the trailing ones, as well as a way to find size and magic. Add a matching line to the extra[] table in auto.c, compile, test and submit to me.

Why freedup does not use hash functions by default

Hash functions should speed up freedup since they avoid comparing files that have been scanned before (and might differ in the last characters). But freedup is slowed down, if files of the same size differ early. Then you should switch the hash function off, which is now the default. If most files of the same size are likely to be identical (more then just two), it probably pays to switch hash functions on. There is an internal hash function that allows some interesting speed enhancements (see below). External hash functions are kept, since they might be interesting to check the internal one for correctness.

The new algorithm records hash sums on the fly (starting in version 1.3-1) and is in worst case - depending on cpu - half as fast as without using hash functions. When reading files the hash function is calculated until the comparison fails. The hash context is stored until the next comparison takes place and if it fails at a later block, the hash calculation will be continued where it stopped earlier. Since reading and comparing files works with data blocks (predefined 4k) the hash values can sometimes be calculated although the comparison fails.

time ./freedup -x mp3 --hash ? -ni /testdir
7856 files; 1 match; average file size 46MB; 50% smaller 4k; 2900 BogoMIPS
2852 classic hash sums to avoid 3411 byte-by-byte comparisons.
hash supportParameterReal TimeUser TimeSys Time
without hash support--hash 02m04.646s0m00.599s0m03.455s
with classic hashsum--hash 15m31.221s2m21.914s0m16.303s
with advanced hash--hash 21m59.720s0m06.006s0m03.515s

time ./freedup --hash ? -n /mp3dir
7919 files; 0 matches; all around average file size 4.5MB; 1400 BogoMIPS
4502 classic hash sums to avoid 3819 byte-by-byte comparisons.
hash supportParameterReal TimeUser TimeSys Time
without hash support--hash 05m21.690s0m15.130s0m25.560s
with classic hashsum--hash 145m14.048s36m33.470s2m29.380s
with advanced hash--hash 210m01.311s6m28.610s0m28.150s

time ./freedup --hash ? -x mp3 -n /mp3dir
7919 files; 456 duplicates; all around average file size 4.5MB; 1400 BogoMIPS
4524 classic hash sums to avoid 3425 byte-by-byte comparisons.
hash supportParameterReal TimeUser TimeSys Time
without hash support--hash 06m48.276s0m18.590s0m28.600s
with classic hashsum--hash 149m35.108s37m06.450s2m47.400s
with advanced hash--hash 212m33.688s6m51.530s0m31.090s

As a consequence of these results, the advantage of hash functions is not obvious for most environments. I assume that there are situations, where many files have the same size and quite similar contents. Then one should switch hash function usage to the advanced mode. But since I do not intend to rely on hash results without having byte-by-byte comparison, I changed the default value since freedup 1.3-2 to off.

Examples

An Example using FREEDUP in native mode: 

SYSTEM1:root# freedup -cf /home/freedup/holidays/2006/family /home/freedup/holidays/2006/friends
Run through both trees .../family and .../friends, compare the files (selections of my holiday snapshots) and link those files, that have identical names and contents. The option -c counts how much space is saved by linking.

An Example to remove duplicate MP3 files:

MP3 files usually contain a tag (indeed there are two different tags that may coexist at the beginning and at the end of the file) that contains more information than the pathname. MP3 files are also copied frequently (for legal reasons) like having it on a MP3 CD for the car, on the stick that is used for jogging or for simple rearrangements from one computer to another. With each further action it starts getting more complicate to know, whether it is a old version or a new one in higher quality (hard disks are getting cheaper). In order to make the situation worse, I tend to correct wrong titles or misspelled Artist names. (Do you know how many 'r', 's', 't' and 'n's are in the artists name who sings "Ironic"?)

I think the motivation should be clear by now. How looks the solution like? My solution is to use FreeDup and its extended style enhancements. Here is the syntax to find out, whether it is a good idea to link files and one should check it manually: 

MP3SYSTEM:root# freedup -inq -x mp3 /music /burn

/music/Alanis_Morissette/Ironic.mp3
/music/HiFi/Alanis_Morissette/Ironic.mp3
/burn/CD/Females/Alanis_Morissette/Ironic.mp3
/burn/CD/CarMix1/Alanis_Morissette/Ironic.mp3
/burn/Stick/Blue/Alanis_Morissette/Ironic.mp3

[...]

Due to the amount of files to link I tend to link them automatically, by omitting -in or replacing it with -c. In case I want to to decide the linking direction case by case I only omit -n. 

MP3SYSTEM:root# freedup -i -x mp3 /music /burn

Extra Style comparisons are not thouroughly tested yet.
You may loose header information, if you press .
Use CTRL-C to stop.
I was used to use CTRL-D to bypass this message. But you should update to a new version. 
4052 files to investigate

Del:Lnk [filesize:devc:i-node:perm:L:tag] <filename>
 0 : A [    81920:0303:00a8c0:0644:1:  ] /music/Alanis_Morissette/Ironic.mp3
 1 : B [    86016:0303:00a8e7:0644:1: 2] /music/HiFi/Alanis_Morissette/Ironic.mp3
 2 : C [    86018:0303:00a8e0:0644:1: 2] /burn/CD/CarMix1/Alanis_Morissette/Ironic.mp3
 3 : D [    86144:0303:00a8bb:0644:1:12] /burn/CD/Females/Alanis_Morissette/Ironic.mp3
 4 : E [    86144:0303:00a8c1:0644:1:12] /burn/Stick/Blue/Alanis_Morissette/Ironic.mp3
Delete on number, Link on letter, Symlink on Capital (first is source)
 to confirm.  to clear. All links will point to <a>.
$ ln <e> <b>; ln <e> <a>; rm <3>; rm <2>;
[...]
When I get the first selection I type 'e', 'b','a','3','2'. When I press return, the commands will be executed. It is easy to erase the command list by typing the escape key. If your decision rules are simple you may use '@','<','>' to link all other files to the first (from command line or standard input), to the oldest or the newest file. But I use CTRL-C to try different options. 

MP3SYSTEM:root# freedup -i /music /burn

If I now start FreeDup without the extra style option, not all identical mp3 codings would have been found, since most files differ (compare sizes). The resulting list is much shorter. Since they are all identical, the size and the tag info (FreeDup does not look for tags then) is not shown. 

4052 files to investigate

Del:Lnk [dev:i-node:perm:L]
 0 : A [0303:00a8bb:0644:1] /burn/CD/Females/Alanis_Morissette/Ironic.mp3
 1 : B [0303:00a8c1:0644:1] /burn/Stick/Blue/Alanis_Morissette/Ironic.mp3
Delete on number, Link on letter, Symlink on Capital (first is source)
 to confirm.  to clear. All links will point to <a>.
$ ln <b> <a>;
[...]

An Example using LOCATE:

The intention is to see, what FreeDup would do on all registered JPEGs on SYSTEM1. We do run the command as root, just to see all allowed links. 

SYSTEM1:root# locate '*.jpg' | freedup -nv

lstat() failed while reading file statistics: No such file or directory
lstat() failed while reading file statistics: No such file or directory
...
lstat() failed while reading file statistics: No such file or directory
lstat() failed while reading file statistics: No such file or directory
1085 files to investigate

ln "/opt/kde3/share/apps/pixie/doc/en/pixielogo.jpg" "/opt/kde3/share/apps/pixie/pixielogo.jpg"
ln "/opt/kde3/share/apps/quanta/templates/binaries/images/jpg/demo.jpg" "/opt/kde3/share/apps/quanta/templates/images/jpg/demo.jpg"
ln "/usr/lib/webmin/mscstyle3/images/cats/net.jpg" "/usr/lib/webmin/mscstyle3/images/cats_over/net.jpg"
ln "/usr/lib/webmin/mscstyle3/images/cats/webmin.jpg" "/usr/lib/webmin/mscstyle3/images/cats_over/webmin.jpg"
ln "/usr/share/games/freedroid/graphics/transfer.jpg" "/usr/src/packages/BUILD/freedroid-0.8.4/graphics/transfer.jpg"
ln "/usr/share/doc/packages/id3lib-devel/attilas_id3logo.jpg" "/usr/src/packages/BUILD/audacity-src-1.0.0/id3lib/doc/attilas_id3logo.jpg"
ln "/usr/share/doc/packages/mgp/sample/mgp3.jpg" "/usr/X11R6/lib/X11/mgp/mgp3.jpg"
ln "/usr/share/doc/packages/mgp/sample/mgp2.jpg" "/usr/X11R6/lib/X11/mgp/mgp2.jpg"
ln "/usr/share/doc/packages/mgp/sample/mgp1.jpg" "/usr/X11R6/lib/X11/mgp/mgp1.jpg"
ln "/opt/kde3/share/apps/kworldclock/maps/caida_bw/1280.jpg" "/usr/X11R6/lib/X11/xglobe/caida_bw_1280.jpg"
ln "/opt/kde3/share/apps/kworldclock/maps/caida/1280.jpg" "/usr/X11R6/lib/X11/xglobe/caida_1280.jpg"
ln "/opt/kde3/share/apps/kworldclock/maps/alt/1200.jpg" "/usr/X11R6/lib/X11/xglobe/alt_1200.jpg"
ln "/opt/kde3/share/apps/kworldclock/maps/bio/1600.jpg" "/usr/X11R6/lib/X11/xglobe/bio_1600.jpg"
ln "/opt/kde3/share/apps/kworldclock/maps/depths/1440.jpg" "/usr/X11R6/lib/X11/xglobe/depths_1440.jpg"
ln "/opt/kde3/share/apps/kworldclock/maps/mggd/1440.jpg" "/usr/X11R6/lib/X11/xglobe/mggd_1440.jpg"
15 files of 1085 will be replaced by links.
The total size of replacable files is 1506387 bytes.
md5 hash algorithm had to read 86 files to avoid 31 file comparisons.

Initially failed lstat() executions show, that the locate database was not updated since the last JPEG removals. The stats of 1085 files have been read and compared after that. 15 files turned out to match 15 others. Most of them seem having been transfered by install commands. The amount of saved space is about 1.5MB. Using the md5 hashing was not a good idea in this case. Instead of reading and evaluating a hash sum it would have been easier to read 62 files for direct comparison.

Please be aware, that the displayed commands cannot be piped into a file and executed later. You need to remove the target first or use ln -f, before you link it. Otherwise you will receive "file exists". Later versions of FreeDup show option -f by default.

An Example using FIND: 

SYSTEM1:root#  find /usr/src/linux -type f -xdev -atime +12 | freedup -nv
SYSTEM1:/home/freedup # find /usr/src/linux -type f -xdev -atime +12 | freedup -c

Taking file names from stdin

0 files to investigate

0 files of 0 replaced by links.
The total size of replaced files was 0 bytes.
md5 hash algorithm had to read 0 files to avoid 0 file comparisons.
The starting tree is not a tree but a symbolic link. You need to append a slash to descend into the referenced directory. This trick only works for the starting tree. 
SYSTEM1:/home/freedup # find /usr/src/linux/ -type f -xdev -atime +12 | time freedup -c

Taking file names from stdin

1045 files to investigate

0 files of 1045 replaced by links.
The total size of replaced files was 0 bytes.
md5 hash algorithm had to read 0 files to avoid 0 file comparisons.
0.00user 0.01system 0:00.29elapsed 6%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+1310minor)pagefaults 0swaps
You see, that I tried FreeDup already before. No file that was not touched for 12 days did match another. -xdev was used to confine the find command to the local directory. The prefix command time was used to show some not very interesting performance statistics. Another way to write it down is 
SYSTEM1:/home/freedup # freedup -c /usr/src/linux/ -o "-xdev -atime +12"

The option passing really pays if you need to scan a number of trees. Just compare yourself: 

SYSTEM1:/home/freedup # freedup -c /usr/src/linux-2.6.12.1 /usr/src/linux-2.6.21.1 -o "-xdev -atime +12"
versus 
SYSTEM1:/home/freedup # ( find /usr/src/linux-2.6.12.1 -type f -xdev -atime +12 ; find /usr/src/linux-2.6.21.1 -type f -xdev -atime +12 ) | time freedup -c
Please note, that I omitted (incorrectly) the find default action -print.

List identical files in groups 

SYSTEM1:/home/freedup/fdupes-1.40 # freedup -in testdir/

14 files to investigate

testdir/two
testdir/twice_one
testdir/recursed_a/two

testdir/recursed_a/one
testdir/recursed_b/one

testdir/recursed_b/three
testdir/recursed_b/two_plus_one

testdir/zero_a
testdir/zero_b

testdir/with spaces a
testdir/with spaces b

Directories to use FreeDup for:

Hints on what FreeDup (seems to) lack

  1. Excess Mode
    Duff provides an "excess mode" that shows clusters of identical files where exactly one is missing. The intention is to remove all duplicates and keep the one that is not shown. The man page of duff suggests to use:
    duff -er . | xargs rm
    In case you want to do the same with FreeDup, your line should read 
    freedup -in . | awk '{if(NF!=0)print x;x=$0}' | xargs rm
    Please be aware that two such concurrently active jobs might delete files, since qsort() of the OS does not provide a kind of sorting that guarantees to keep two identical files in their original order.

  2. Convert Symbolic Links To Real Files
    Duff also provides a "reverse mode" that converts symbolically linked files back to plain files, which are not linked to their original source. If this is generally desired you may want to use: 
    find test -type l -exec cp {} {}.tmp$$ \; -exec mv {}.tmp$$ {} \;

  3. Convert Symbolic Links To Hard Links
    If you wish to replace symbolic links by hard links, I may provide you two alternatives. One is using a shell script soft2hard The other uses my own C code of a command symharden, which accepts a single symbolic link that will be replaced by a hard link if possible. It will fail with non-zero return code in all other cases. Please be aware that the usual restriction for links apply, i.e. no cross-device links. Use this line to do it for a full tree: 
    find test -type l -exec symharden {} \;

  4. Hard-Linking directories
    some operating systems support linking of directories on some file systems with the link (not possible with ln) command. Since the testing environment does not provide such functionality, there is no option for it. On the other hand, it would probably not significantly change the file system size.

  5. Exclude Directories
    FreeDup does not really provide to exclude directories by full or partial path name. But since you may prepare any file list, you are able to do this as well. For me mostly two situations apply: You may easily think of other solutions following this patterns.

  6. Directory Modification Times
    When linking files it is unavoidable to change the modification and the access time of the directory the target belongs to. Carsten Schmidt reported me a case where this leads to additional (unwanted) actions. Use the -T option to make FreeDup keeping the modification times of the directories. Since FreeDup avoids locking, there is a little chance for another process to modify the directory while the access date is (mis)corrected.
    NB: The full time stamp of the linked file is the one of the link source. After linking any modification would affect link source and target.

  7. Removing empty files or directories
    With Linux this a simple command line would do it for directories: 
    find ./ -type d -empty -print0 | xargs -0 rmdir
    and another one for empty files 
    find ./ -type f -empty -print0 | xargs -0 rm
    Both lines allow to use line feeds within the file names, since they use zero limited strings (This hint is from the readme of dupmerge).
    With a non GNU-like OS this command line would do it for directories: 
    find ./ -type d -size 0c -print | xargs rmdir
    and a similar one for empty files: 
    find ./ -type f -size 0c -print | xargs rm

  8. Finding Linked files with Windows
    Kurt pointed out how hard it can be to find linked files within Windows (compare: junction systeminternals). He suggests this command using cygwin: 
    find . -type f -noleaf -links +1 -printf "%n %i %f\t%h\n" | sort | less

Hints on (previous) strange behaviour of FreeDup

Quality Verification

Starting with version 1.0-5 the binary installation provides a file called verify. This is partially identical to the testing routines of the source package. Please be aware, that you have to be root to be successful with all tasks since there are test files given to other users (bin.bin, except for cygwin: ASPNET.SYSTEM). In version 1.0-5 there is also a good chance that the intercative test fails, when the sorting order (which was not defined!) differs from my development system.

Hash Evaluation

The versions before 1.0-4 do not support an internal hash sum calculation. External hash programs give you the disadvantage of speed loss, since the hash sums are calculated separately (use -# to switch hashsums off). The advantage is, that you may use nearly every external program that generates hash sums. You have to set the paths at compile time or move/link the executables to where they are expected.

The use of external programs may cause strange effects, if they do not work as expected. This was the reason why the cygwin versions before 1.0-3 all had no hash support. Version 1.0-3 does no strict testing, but checks that the output format matches the format that FreeDup needs. On my development system (SuSE Linux 10) the output to sha1sum freedup reads 

284abef5f109e88d8e997a8756c6fe396dade795  freedup
while it reads under cygwin 
284abef5f109e88d8e997a8756c6fe396dade795 *freedup

Freedup expects a 40 byte hash sum for sha1sum and 32 alphanumeric bytes for md5sum. The use of the 16 bytes output from sum is not really considered helpful, but provided as fallback. The spaces (for cygwin the second is an asterisk) after the hash code are checked to be there (details are in the definition around the hashme[] within the source). If not, it is assumed that the hash methods quite certainly provide misleading results. Therefore they are disabled automatically. Prior to version 1.1 you see output like this if the output format does not match: 

$ freedup /home/peter/
md5: format does not match ('/' instead of ' ')
sum: format does not match ('i' instead of ' ')
No working hashmethod found.
--> Use of hash methods is disabled.
[...]

Starting with version 1.0-4, FreeDup provides an internal hash method as default and fallback method, but allows a free choice between an internal and the external hash methods.

Questions

The Frequently Asked Ones are not on this page, since there is an excellent FAQ section
on William Stearns freedups page http://www.stearns.org/freedups/README
Please note, that freedup is a completely independant implementation, with other means and other capabilities.
The Main difference is the ability of freedup to provide symlinks from different file systems.

And here are my questions.
How do you like the performance of freedup?
Are the provided packages what you want?
What about the documentation. Is it sufficient?
Please provide me some feedback here or per mail.

Users Comments

Wiki: Howto use Freedup to improve rsnapshop.
A discussion on FreeDup in conjunction with rsnapshot.
Verschiedene Meinungen zu Freedup und Alternativen in Deutsch.
Frühjahrs-/Winter-Putz im RadioTux-Blog
Japanese Selection of hot linux tools
Japanese Comment on Aikawa.TV
Miroslav Suchy resports on root.cz.
However, I hope the Japanese and Czech comments are positive. I am fortunate to tell, there are currently no unresolved bug reports.

Co-Publishing

On FreshMeat.Net by myself immediately after completed upload to these pages.
On IceWalkers a bit delayed by myself and others.
On Softpedia by somebody else.
There are also several download pages referenced, that supply the codes for various releases.

Contacts and Credits

Please send comments, suggestions, bug reports, patches, and/or additions to AN@freedup.org .

A lot of different web sites were helpful. I used William Stearns freedups for many years quite successfully until I lacked some features, which freedup fixes.

Thanks for compiling and publishing to Tony Graffy on SuSE RPMs at packmans and Dag Wieers on RedHat, CentOS and Fedora RPMs at his own site.

Thanks to Tomasz Muras with his Perfect Match for being a fair competitor.

Thanks to Thorsten Leemhuis and c't (24/2007) on writing and publishing "Auswahl satt", which is a German article about "System-Utlities für Linux", which covers these topics: file managers, sorting & finding, and archiving files. Freedup was his choice to find and link duplicate files.

Thanks to Michael Riepe and iX (11/2007) on writing and publishing "Entdoppeltes Lottchen", which is a German article about "Dateien mit gleichem Inhalt finden und beseitigen". He spent one third of the article on freedup (counting paragraphs).

My thanks to all the individuals who were asking me for certain improvements or corrections. This raised the usability of Freedup and therefore helped them, others and me. [I do not publish names of communication partners using private mail, except being explicitely authorized.]

Donations

This software is for free of charge. On the other hand there also no liability for whatsoever.

Just in case you feel obliged to provide me some return and you are not contributing in other ways to the software community, I kindly ask you to visit my advertisment section. If you intend to buy one of the offerings there, I will receive some bonus.

        FREE DUP        allows you to reclaim space on your drives.
Action: show only   link hard when possible symbolic otherwise   only link hard   only link symbolic  
Link Direction: Arbitrary   to first   to most linked   to oldest   to newest   to biggest   to smallest  
Extra Style: Off   Auto   MP3   MP4   MPC   Ogg   JPG  
Directory 1:
Directory 2:
Directory 3:
File & Owner: user needs to be identical     group needs to be identical     file name needs to be identical    
Permission: needs to be identical    whereever this octal mask is nonzero.
Modif. Time: needs to be identical    or it differ by a maximum of seconds. keep directory time stamp.
Other: show already linked files too   do not link empty files  
Work Dir:
Hash Support: None   Optimized   Built-In   md5   sha1   sha224   sha256   sha384   sha512