diff options
| -rw-r--r-- | system/zerofree/zerofree.8 | 92 | ||||
| -rw-r--r-- | system/zerofree/zerofree.SlackBuild | 11 | ||||
| -rw-r--r-- | system/zerofree/zerofree.info | 10 |
3 files changed, 108 insertions, 5 deletions
diff --git a/system/zerofree/zerofree.8 b/system/zerofree/zerofree.8 new file mode 100644 index 0000000000..fb6f277e7b --- /dev/null +++ b/system/zerofree/zerofree.8 @@ -0,0 +1,92 @@ +.TH "ZEROFREE" "8" +.SH "NAME" +zerofree \(em zero free blocks from ext2, ext3 and ext4 file-systems +.SH "SYNOPSIS" +.PP +\fBzerofree\fR [\fB-n\fP] [\fB-v\fP] [\fB-f fillval\fP] \fIfilesystem\fR +.SH "DESCRIPTION" +.PP +\fBzerofree\fR finds the unallocated, +blocks with non-zero value content in an ext2, ext3 or ext4 +\fIfilesystem\fR (e.g. /dev/hda1) and +fills them with zeroes (or another octet of your choice). + + +.PP +Filling unused areas with zeroes 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. + +.PP +Filling unused areas may also be useful with solid-state +drives (SSDs). On some SSDs, filling blocks with ones (0xFF) +is reported to trigger Flash block erasure by the firmware, +possibly giving a write performance increase. + +.PP +The usual way to achieve the same result (zeroing the +unallocated blocks) is to run \fBdd\fR (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: +.IP " \(bu" 6 +it is slow; +.IP " \(bu" 6 +it makes the disk image (temporarily) grow to its maximal +extent; +.IP " \(bu" 6 +it (temporarily) uses all free space on the disk, so other +concurrent write actions may fail. + +.PP +\fIfilesystem\fR has to be unmounted or +mounted read-only for \fBzerofree\fR to work. It +will exit with an error message if the +\fIfilesystem\fR is mounted writable. To +remount the root file-system readonly, you can first switch to +single user runlevel (\fBtelinit 1\fR) then use +\fBmount \-o remount,ro +\fIfilesystem\fR\fR. + +.PP +\fBzerofree\fR has been written to be run +from GNU/Linux systems installed as guest OSes inside a virtual +machine. In this case, it is typically run from within the guest +system, and a utility is then run from the host system to shrink +disk image (\fBVBoxManage modifyhd \-\-compact\fR, +provided with virtualbox, is able to do that for some disk image +formats). + +.PP +It may however be useful in other situations: for instance +it can be used to make it more difficult to retrieve deleted +data. Beware that securely deleting sensitive data is not in +general an easy task and usually requires writing several times +on the deleted blocks. + +.SH "OPTIONS" +.IP "\fB-n\fP " 10 +Perform a dry run (do not modify the file-system); +.IP "\fB-v\fP " 10 +Be verbose; +.IP "\fB-f value\fP " 10 +Specify the octet value to fill empty blocks with (defaults to +0). Argument must be within the range 0 to 255. +.SH "SEE ALSO" +.PP +dd (1). +.SH "AUTHOR" +.PP +This manual page was written by Thibaut Paumard <paumard@users.sourceforge.net> for +the \fBDebian\fP 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. + +.PP +On Debian systems, the complete text of the GNU General Public +License can be found in /usr/share/common-licenses/GPL-2. + +.\" created by instant / docbook-to-man, Mon 31 Mar 2014, 15:41 diff --git a/system/zerofree/zerofree.SlackBuild b/system/zerofree/zerofree.SlackBuild index 239c325907..046cd21bcc 100644 --- a/system/zerofree/zerofree.SlackBuild +++ b/system/zerofree/zerofree.SlackBuild @@ -22,9 +22,11 @@ # OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF # ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +# 20141021 bkw: add man page, add sparsify, bump BUILD to 2. + PRGNAM=zerofree VERSION=${VERSION:-1.0.3} -BUILD=${BUILD:-1} +BUILD=${BUILD:-2} TAG=${TAG:-_SBo} if [ -z "$ARCH" ]; then @@ -77,6 +79,13 @@ strip --strip-unneeded $PRGNAM 2> /dev/null mkdir -p $PKG/usr/sbin cp -a $PRGNAM $PKG/usr/sbin +# This looks useful, include it. +gcc $SLKCFLAGS -Wl,-s -o $PKG/usr/sbin/sparsify $CWD/sparsify.c -lext2fs + +# man page comes from Debian. +mkdir -p $PKG/usr/man/man8 +gzip -9c $CWD/$PRGNAM.8 > $PKG/usr/man/man8/$PRGNAM.8.gz + mkdir -p $PKG/usr/doc/$PRGNAM-$VERSION cp -a COPYING $PKG/usr/doc/$PRGNAM-$VERSION cat $CWD/$PRGNAM.SlackBuild > $PKG/usr/doc/$PRGNAM-$VERSION/$PRGNAM.SlackBuild diff --git a/system/zerofree/zerofree.info b/system/zerofree/zerofree.info index 4720d45995..1a7582daa8 100644 --- a/system/zerofree/zerofree.info +++ b/system/zerofree/zerofree.info @@ -1,10 +1,12 @@ PRGNAM="zerofree" VERSION="1.0.3" HOMEPAGE="http://intgat.tigress.co.uk/rmy/uml/index.html" -DOWNLOAD="http://intgat.tigress.co.uk/rmy/uml/zerofree-1.0.3.tgz" -MD5SUM="7fffca9639a2acc9c889c49b3f94a0c6" +DOWNLOAD="http://intgat.tigress.co.uk/rmy/uml/zerofree-1.0.3.tgz \ + http://intgat.tigress.co.uk/rmy/uml/sparsify.c" +MD5SUM="7fffca9639a2acc9c889c49b3f94a0c6 \ + 919ad782c7120d1e4a9c0ccc9f45b8ef" DOWNLOAD_x86_64="" MD5SUM_x86_64="" REQUIRES="" -MAINTAINER="B Watson" -EMAIL=" yalhcru@gmail.com" +MAINTAINER="B. Watson" +EMAIL="yalhcru@gmail.com" |