manpage.1'. You may view
the manual page with: `docbook-to-man manpage.sgml | nroff -man |
less'.
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Thibaut">
Paumard">
February 6, 2008">
8">
<paumard@users.sourceforge.net>">
ZEROFREE">
Debian">
GNU">
GPL">
]>
&dhemail;
&dhfirstname;
&dhsurname;
2003&dhusername;
&dhdate;
&dhucpackage;
&dhsection;
&dhpackage;zero free blocks from ext2/3/4 file-systems&dhpackage;
filesystemDESCRIPTION&dhpackage; finds the unallocated,
non-zeroed blocks in an ext2, ext3, or ext4
filesystem (e.g. /dev/hda1) and
fills them with zeroes. This is useful if the device on which
this file-system resides is a disk image. In this case,
depending on the type of disk image, a secondary utility may be
able to reduce the size of the disk image after zerofree has
been run.The usual way to achieve the same result (zeroing the
unallocated blocks) is to run dd (1) to
create a file full of zeroes that takes up the entire free
space on the drive, and then delete this file. This has many
disadvantages, which zerofree alleviates:it is slow;it makes the disk image (temporarily) grow to its maximal
extent;it (temporarily) uses all free space on the disk, so other
concurrent write actions may fail.filesystem has to be unmounted or
mounted read-only for &dhpackage; to work. It
will exit with an error message if the
filesystem is mounted writable. To
remount the root file-system readonly, you can first switch to
single user runlevel (telinit 1) then use
mount -o remount,ro
filesystem.&dhpackage; has been written to be
run from GNU/Linux systems installed as guest OSes inside a
virtual machine. It may however be useful in other
situations.OPTIONSPerform a dry run (do not modify the file-system);Be verbose.SEE ALSOdd (1).AUTHORThis manual page was written by &dhusername; &dhemail; for
the &debian; system (but may be used by others). Permission is
granted to copy, distribute and/or modify this document under
the terms of the &gnu; General Public License, Version 2 or any
later version published by the Free Software Foundation.
On Debian systems, the complete text of the GNU General Public
License can be found in /usr/share/common-licenses/GPL-2.