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diff --git a/misc-utils/wipefs.8 b/misc-utils/wipefs.8 new file mode 100644 index 0000000..303e661 --- /dev/null +++ b/misc-utils/wipefs.8 @@ -0,0 +1,148 @@ +.\" Copyright 2009 by Karel Zak. All Rights Reserved. +.\" This file may be copied under the terms of the GNU Public License. +.\" +.TH WIPEFS 8 "December 2014" "util-linux" "System Administration" +.SH NAME +wipefs \- wipe a signature from a device +.SH SYNOPSIS +.B wipefs +.RB [ options ] +.IR device ... +.sp +.B wipefs +.RB [ \-\-backup ] +.B \-o +.I offset +.IR device ... +.sp +.B wipefs +.RB [ \-\-backup ] +.B \-a +.IR device ... +.SH DESCRIPTION +.B wipefs +can erase filesystem, raid or partition-table signatures (magic strings) from +the specified +.I device +to make the signatures invisible for libblkid. +.B wipefs +does not erase the filesystem itself nor any other data from the device. + +When used without any options, wipefs lists all visible filesystems and the +offsets of their basic signatures. The default output is subject to change. +So whenever possible, you should avoid using default outputs in your scripts. +Always explicitly define expected columns by using +.B \-\-output +.I columns-list +in environments where a stable output is required. + +.B wipefs +calls the BLKRRPART ioctl when it has erased a partition-table signature +to inform the kernel about the change. The ioctl is called as the last step +and when all specified signatures from all specified devices are already erased. +This feature can be used to wipe content on partitions devices as well as partition +table on a disk device, for example by \fBwipefs \-a /dev/sdc1 /dev/sdc2 /dev/sdc\fR. + +Note that some filesystems and some partition tables store more magic strings on +the device (e.g., FAT, ZFS, GPT). The +.B wipefs +command (since v2.31) lists all the offset where a magic strings have been +detected. + +When option \fB\-a\fR is used, all magic strings that are visible for libblkid are +erased. In this case the +.B wipefs +scans the device again after each modification (erase) until no magic string is found. + +Note that by default +.B wipefs +does not erase nested partition tables on non-whole disk devices. +For this the option \fB\-\-force\fR is required. + +.SH OPTIONS +.TP +.BR \-a , " \-\-all" +Erase all available signatures. The set of erased signatures can be +restricted with the \fB\-t\fR option. +.TP +.BR \-b , " \-\-backup" +Create a signature backup to the file $HOME/wipefs-<devname>-<offset>.bak. +For more details see the \fBEXAMPLE\fR section. +.TP +.BR \-f , " \-\-force" +Force erasure, even if the filesystem is mounted. This is required in +order to erase a partition-table signature on a block device. +.TP +.BR \-h , " \-\-help" +Display help text and exit. +.TP +.BR \-J , " \-\-json" +Use JSON output format. +.TP +\fB\-\-lock\fR[=\fImode\fR] +Use exclusive BSD lock for device or file it operates. The optional argument +\fImode\fP can be \fByes\fR, \fBno\fR (or 1 and 0) or \fBnonblock\fR. If the \fImode\fR +argument is omitted, it defaults to \fB"yes"\fR. This option overwrites +environment variable \fB$LOCK_BLOCK_DEVICE\fR. The default is not to use any +lock at all, but it's recommended to avoid collisions with udevd or other +tools. +.TP +.BR \-i , " \-\-noheadings" +Do not print a header line. +.TP +.BR \-O , " \-\-output " \fIlist\fP +Specify which output columns to print. Use \-\-help to +get a list of all supported columns. +.TP +.BR \-n , " \-\-no\-act" +Causes everything to be done except for the write() call. +.TP +.BR \-o , " \-\-offset " \fIoffset\fP +Specify the location (in bytes) of the signature which should be erased from the +device. The \fIoffset\fR number may include a "0x" prefix; then the number will be +interpreted as a hex value. It is possible to specify multiple \fB\-o\fR options. +.sp +The \fIoffset\fR argument may be followed by the multiplicative +suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB +(the "iB" is optional, e.g., "K" has the same meaning as "KiB"), or the suffixes +KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB. +.TP +.BR \-p , " \-\-parsable" +Print out in parsable instead of printable format. Encode all potentially unsafe +characters of a string to the corresponding hex value prefixed by '\\x'. +.TP +.BR \-q , " \-\-quiet" +Suppress any messages after a successful signature wipe. +.TP +.BR \-t , " \-\-types " \fIlist\fP +Limit the set of printed or erased signatures. More than one type may +be specified in a comma-separated list. The list or individual types +can be prefixed with 'no' to specify the types on which no action should be +taken. For more details see mount(8). +.TP +.BR \-V , " \-\-version" +Display version information and exit. +.SH ENVIRONMENT +.IP LIBBLKID_DEBUG=all +enables libblkid debug output. +.IP LOCK_BLOCK_DEVICE=<mode> +use exclusive BSD lock. The mode is "1" or "0". See \fB\-\-lock\fR for more details. +.SH EXAMPLE +.TP +.B wipefs /dev/sda* +Prints information about sda and all partitions on sda. +.TP +.B wipefs \-\-all \-\-backup /dev/sdb +Erases all signatures from the device /dev/sdb and creates a signature backup +file ~/wipefs-sdb-<offset>.bak for each signature. +.TP +.B dd if=~/wipefs-sdb-0x00000438.bak of=/dev/sdb seek=$((0x00000438)) bs=1 conv=notrunc +Restores an ext2 signature from the backup file ~/wipefs-sdb-0x00000438.bak. +.SH AUTHORS +Karel Zak <kzak@redhat.com> +.SH SEE ALSO +.BR blkid (8), +.BR findfs (8) +.SH AVAILABILITY +The wipefs command is part of the util-linux package and is available from +https://www.kernel.org/pub/linux/utils/util-linux/. |