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Text File  |  1987-04-20  |  4KB  |  126 lines
  1.           DELZ (Delete file entirely)             Steven Holzner
  2.           Command
  3.           Copyright (c) 1986, Ziff-Davis Publishing Co.
  4.           _______________________________________________________
  5.  
  6.           Purpose:  Allows you to delete a file absolutely by
  7.                     writing over the sector(s) it occupies.
  8.  
  9.           Format:   DELZ
  10.  
  11.                     then
  12.  
  13.                     DEL/Z [d:][path][filename[.ext]]
  14.  
  15.           Remarks:  DOS does not delete files by overwriting
  16.                     them.  Rather, the sectors used by the
  17.                     "erased" file are simply made available for
  18.                     use by subsequently written files.  Until
  19.                     they are so used, however, the original file
  20.                     can be recovered with UNDEL.COM (included in
  21.                     these utilities) or by using a comparable
  22.                     commercial product.
  23.  
  24.                     Because it overwrites the sectors used by a
  25.                     file, DELZ provides complete deletion.  A
  26.                     memory-resident utility, it attaches itself
  27.                     to DOS when loaded, normally as a command
  28.                     entered through your AUTOEXEC.BAT file.
  29.                     Thereafter, until you reboot, it provides a
  30.                     /Z (for "zero out") option for the DEL
  31.                     command.
  32.  
  33.           Example:  The disk from which you boot up your PC on
  34.                     drive A: has a copy of DELZ.COM on it, and
  35.                     the disk in drive B: has a file called
  36.                     TAXCHEAT.85 that you wish to ensure is
  37.                     completely obliterated.  From the A> prompt
  38.                     you enter DELZ to load the command into
  39.                     memory.  Then you enter
  40.  
  41.                          DEL/Z B:TAXCHEAT.85
  42.  
  43.                     Even if the TAXCHEAT.85 file is unerased, its
  44.                     original contents will now be unrecoverable.
  45.                     (The contents of that file will, in fact, be
  46.                     the machine language code of DELZ.COM
  47.                     itself.)
  48.  
  49.                     Notes:
  50.  
  51.                     1.   The Z in DEL/Z must be typed uppercase.
  52.                          The use of the global characters ? and *
  53.                          is supported.
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  62.                                  Page -1-
  63.                   2.   Because of possible conflicts with other
  64.                          memory-resident programs and utilities,
  65.                          you must check whether DELZ can be
  66.                          installed on your own system.  While
  67.                          SideKick has caused no reported
  68.                          difficulties, running XyWrite II or III,
  69.                          with or without its XYKBD.COM file, is
  70.                          impossible after DELZ is made resident.
  71.  
  72.                     3.   The use of DELZ.COM is likely to be
  73.                          reasonably infrequent, but sometimes it
  74.                          will be absolutely necessary.  If you
  75.                          find at those times that co-residency
  76.                          conflicts prevent putting it in your
  77.                          AUTOEXEC.BAT file, you may wish to keep
  78.                          a bootable disk (formatted with the /S
  79.                          option) with a copy of DELZ.COM and an
  80.                          AUTOEXEC.BAT file that loads the
  81.                          program.  If you then boot up from this
  82.                          disk you can destroy any file(s) you
  83.                          wish, remove the DELZ disk, and reboot
  84.                          your computer normally.
  85.  
  86.                     4.   Requires DOS 2.0 or higher.
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  125.                                  Page -2-
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