SYNOPSIS

       zeroer

DESCRIPTION

       The  zeroer  utility can be used to flush the empty space on a disk. In
       contrary to the dd utility, zeroer doesn't wipe  existing  files  on  a
       partition.  It  overwrites  the  unallocated disk space around existing
       files, which means that deleted files cannot be restored anymore  after
       processing  a  certain  partition  with zeroer. The utility's principle
       consists in writing huge zero-padded memory blocks to a file. To a cer-
       tain  extent  this  works  similarly  to the dd program, however zeroer
       dynamically reduces the blockwriter's buffer  size  when  the  disk  is
       going  to  be  full.  Thus,  smaller fragments of unallocated partition
       space are also flushed, even though the largest unallocated disk  areas
       can be written with huge blocks and this means more speed.

       zeroer's  principle  is  quite  simple  and  there is no guarantee that
       zeroer works reliably on every file system, because zeroer doesn't know
       the  way  a file system works exactly. However, most file systems use a
       mix of a centralized disk block addressing  table  (e.g.  inodes,  file
       allocation  table) and multiple peripheral directory/ file descriptors.
       zeroer has been multi-pass tested on UFS, FAT and  NTFS  and  the  test
       results show that zeroer operates quite reliably on those file systems.

TODO

       The current version of zeroer doesn't remove  file  or  directory  meta
       data  like file and directory names, sizes, dates, modes. Only a file's
       content is overwritten. Metadata scrambling will be  implemented  in  a
       future release.

LICENSE

       zeroer is released under the GPL.

THANKS

       Emanuel Haupt <ehaupt@FreeBSD.org> for creating a FreeBSD port.



David Schneider                       0.1                            zeroer(1)