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zeroer(1)							     zeroer(1)

NAME
       zeroer -- wipe unallocated disk space around files

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  dy-
       namically  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  ze-
       roer  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 al-
       location	 table)	 and  multiple peripheral directory/ file descriptors.
       zeroer has been multi-pass tested on UFS, FAT and NTFS and the test re-
       sults 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)

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