
                         +----------------------+
                         |                      |
                         |  ***  UDUP 0.6  ***  |
                         |                      |
                         +----------------------+


   DOS Seek-and-Delete program for duplicate files. Compares up to 65535 files
   on any drive. ONLY useable if you have a registered copy of UDEC!


 - UDUP 0.6
    Syntax : udup [-Options] [lw:\path\file.ext]
             Wildcards allowed !
             e.g. udup c:\*.uue d: -sco!

   Options: -A  verbose output
            -B  surpresses video output while redirecting standard output
            -C  deletes automatically duplicate files
               -C0 lists only filenames of duplicate files
               -C1 deletes the first file of 2 duplicate files
               -C,-C2 deletes the second file of 2 duplicate files
               -Co deletes the older file of 2 duplicate files
                   (the 2nd otherwise)
               -C! deletes without confirmation
            -S  seek and delete in subdirectories
            -T  lists additionally filedate
            -X  prevents XMS-access


 - Call the program at your DOS prompt:
   > udup c: d: e: /s < will compare all files on drives c, d, and e.
   Wildcards "?" and "*" are allowed, e.g. > udup c:\*.exe d:\*.exe /s <

 - UDUP first creates a list of all specified files and then sorts them into a
   hashtable. This enables UDUP to find files having the same length REALLY
   quickly. (btw., UDUP uses "filelength mod 256" as the hashfunction)
   If you give several file specifications that may overlap to some extent
   (e.g.> udup c:\*.exe c: /s <), UDUP sorts only ONE of perhaps several
   identical files into the table.

 - After this UDUP lists all files with length NULL and prompts you if you want
   to delete these files. Use the option "-C" to delete those files
   automatically.

 - Now UDUP will work through the hashtable, comparing files with the same
   length. If UDUP finds more than 2 files of the same length, a 16 bit CRC
   is computed and only files with the same CRC will be compared further.
   To minimize file accesses and to optimize speed, UDUP uses a caching
   technique, reading a potentially duplicate file completely into memory
   and thus preventing re-reading if there are more than two files to compare.

 - If duplicate files are found, you're able to delete
    [0] no file,
    [1] the first file in the list of duplicate files,
    [2] the duplicate files

 - Option "-C" deletes duplicate files automatically. Write-protected files
   won't be deleted. Option "-C0" only lists duplicate files without deleting
   them.

 - The total number of files UDUP is able to compare depends on the amount of
   free conventional memory and the total number of existing directories.
   To prevent memory overflow, UDUP uses XMS to store filenames. Tests showed
   that, with 600k free conventional memory (UDUP taking up 80k), it's
   posssible to compare max. 58,000 files.

 - If you're running into unexpected runtime-errors, disable the XMS-access
   with the parameter "-X". Note that the max. number of files UDUP is able to
   compare shrinks to some 20,000 in this case.


Warranty:
  - This program is provided as is with no written or implied warranty.
  - The author shall in no event be held liable to you or anyone else
    for any damage of any kind, incidental or consequential, arising
    from the use or the inability to use this program.

    Peter Liebel                       liebel@cip.informatik.uni-wuerzburg.de
    Friedhofstr.17                     liebel@informatik.uni-wuerzburg.de
    97526  Sennfeld  (Deutschland)


