DragonFly On-Line Manual Pages

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
       certain 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)