.\" This file may be copied under the terms of the GNU Public License.
.\"
.\" Based on uuidgen, Mon Sep 17 10:42:12 2000, Andreas Dilger
-.TH BLKID 8 "February 2009" "Linux" "MAINTENANCE COMMANDS"
+.TH BLKID 8 "February 2011" "Linux" "MAINTENANCE COMMANDS"
.SH NAME
-blkid \- command\-line utility to locate/print block device attributes
+blkid \- locate/print block device attributes
.SH SYNOPSIS
.B blkid
.RB \-L
.IR list ]
.RB [ \-u
.IR list ]
-.I device
-[\fIdevice\fR ...]
+.IR device " ... "
.in -9
.B blkid
.IR format ]
.RB [ \-s
.IR tag ]
-.I device
-[\fIdevice\fR ...]
+.IR device " ... "
.SH DESCRIPTION
The
.B blkid
-program is the command-line interface to working with
+program is the command-line interface to working with the
.BR libblkid (3)
-library. It can determine the type of content (e.g. filesystem, swap)
-a block device holds, and also attributes (tokens, NAME=value pairs)
+library. It can determine the type of content (e.g. filesystem or swap)
+that a block device holds, and also attributes (tokens, NAME=value pairs)
from the content metadata (e.g. LABEL or UUID fields).
.PP
.B blkid
has two main forms of operation: either searching for a device with a
specific NAME=value pair, or displaying NAME=value pairs for one or
-more devices.
+more specified devices.
.SH OPTIONS
The \fIsize\fR and \fIoffset\fR arguments may be followed by binary (2^N)
suffixes KiB, MiB, GiB, TiB, PiB and EiB (the "iB" is optional, e.g. "K" has the
Display a usage message and exit.
.TP
.B \-i
-Display I/O Limits (aka I/O topology) information. The 'export' output format is
-automatically enabled. This option could be used together with \fB-p\fR option.
+Display I/O Limits (aka I/O topology) information. The 'export' output format is
+automatically enabled. This option can be used together with the \fB-p\fR option.
.TP
.B \-l
-Look up one device that matches the search parameter specified using
-the
+Look up only one device that matches the search parameter specified with the
.B \-t
option. If there are multiple devices that match the specified search
parameter, then the device with the highest priority is returned, and/or
.B blkid
will print all of the devices that match the search parameter.
.TP
-.B \-L " label "
-Look up one device that uses the label (same as: -l -o device -t
-LABEL=<label>). This look up method is able to reliable use /dev/disk/by-label
-udev symlinks (depends on setting in /etc/blkid.conf). Avoid to use the
-symlinks directly. It is not reliable to use the symlinks without verification.
+.BI \-L " label"
+Look up the device that uses this \fIlabel\fR (equal to: -l -o device -t
+LABEL=<label>). This lookup method is able to reliably use /dev/disk/by-label
+udev symlinks (dependent on a setting in /etc/blkid.conf). Avoid using the
+symlinks directly; it is not reliable to use the symlinks without verification.
The \fB-L\fR option works on systems with and without udev.
Unfortunately, the original
.B blkid(8)
from e2fsprogs use the \fB-L\fR option as a
-synonym to the \fB-o list\fR option. For better portability use "-l -o device
--t LABEL=<label>" and "-o list" in your scripts rather than -L option.
+synonym for the \fB-o list\fR option. For better portability, use \fB-l -o device
+-t LABEL=<label>\fR and \fB-o list\fR in your scripts rather than the \fB-L\fR option.
.TP
-.B \-n " list "
-Restrict probing functions to defined (comma separated) list of superblock types (names).
-The list can be prefixed with "no" to specify the types which should be ignored.
+.BI \-n " list "
+Restrict the probing functions to the specified (comma-separated) \fIlist\fR of
+superblock types (names).
+The list items may be prefixed with "no" to specify the types which should be ignored.
For example:
.sp
blkid -p -n vfat,ext3,ext4 /dev/sda1
.sp
probes for vfat, ext3 and ext4 filesystems, and
.sp
- blkid -p -u nominix /dev/sda1
+ blkid -p -n nominix /dev/sda1
.sp
-probes for all supported formats exclude minix filesystem. This option is
-useful with
-\fB-p\fR only.
+probes for all supported formats except minix filesystems.
+This option is only useful together with \fB-p\fR.
.TP
.BI \-o " format"
Display
print the value of the tags
.TP
.B list
-print the devices in a user-friendly format, this output format is unsupported
+print the devices in a user-friendly format; this output format is unsupported
for low-level probing (\fB-p\fR or \fB-i\fR)
.TP
.B device
-print the device name only, this output format is always enabled for \fB-L\fR
+print the device name only; this output format is always enabled for \fB-L\fR
and \fB-U\fR options
.TP
.B udev
-print key="value" pairs for easy import into the udev environment. The keys are
-prefixed by ID_FS_ or ID_PART_ prefixes.
+print key="value" pairs for easy import into the udev environment; the keys are
+prefixed by ID_FS_ or ID_PART_ prefixes
-The udev output returns ID_FS_AMBIVALENT tag if more superblocks are detected,
+The udev output returns the ID_FS_AMBIVALENT tag if more superblocks are detected,
and ID_PART_ENTRY_* tags are always returned for all partitions including empty
partitions.
.TP
.B export
-print key=value pairs for easy import into the environment. This output format
-is automatically enabled when I/O Limits (\fB-i\fR option) are requested.
+print key=value pairs for easy import into the environment; this output format
+is automatically enabled when I/O Limits (\fB-i\fR option) are requested
.RE
.TP
.BI \-O " offset"
-Probe at the given offset (only useful with \fB-p\fR). This option could be
-used together with \fB-i\fR option.
+Probe at the given \fIoffset\fR (only useful with \fB-p\fR). This option can be
+used together with the \fB-i\fR option.
.TP
.BI \-p
Switch to low-level superblock probing mode (bypass cache).
If there are no devices specified on the command line, all block devices
will be searched; otherwise only the specified devices are searched.
.TP
-.B \-u " list "
-Restrict probing functions to defined (comma separated) list of "usage" types.
-Supported usage types are: filesystem, raid, crypto and other. The list can be
-prefixed with "no" to specify the usage types which should be ignored. For example:
+.BI \-u " list "
+Restrict the probing functions to the specified (comma-separated) \fIlist\fR of "usage" types.
+Supported usage types are: filesystem, raid, crypto and other. The list items may be
+prefixed with "no" to specify the usage types which should be ignored. For example:
.sp
blkid -p -u filesystem,other /dev/sda1
.sp
-probes for all filesystems and others (e.g. swap) formats, and
+probes for all filesystem and other (e.g. swap) formats, and
.sp
blkid -p -u noraid /dev/sda1
.sp
-probes for all supported formats exclude RAIDs. This option is useful with
-\fB-p\fR only.
+probes for all supported formats except RAIDs.
+This option is only useful together with \fB-p\fR.
.TP
-.B \-U " uuid "
-Look up one device that uses the uuid. For more details see the \fB-L\fR option.
+.BI \-U " uuid "
+Look up the device that uses this \fIuuid\fR. For more details see the \fB-L\fR option.
.TP
.B \-v
Display version number and exit.
.I writecachefile
instead of writing it to the default cache file
.IR /etc/blkid.tab .
-If you don't want to save the cache to the default file, specify
+If you don't want to save the cache at all, specify
.IR /dev/null.
-If not specified it will be the same file as that given by the
+If not specified, it will be the same file as that given with the
.B \-c
option.
.TP
devices, 0 is returned.
If the specified token was not found, or no (specified) devices could be
-identified an exit code of 2 is returned.
+identified, an exit code of 2 is returned.
For usage or other errors, an exit code of 4 is returned.
-If the ambivalent low-level probing result was detected an exit code of 8 is
+If the ambivalent low-level probing result was detected, an exit code of 8 is
returned.
.SH AUTHOR
.B blkid
.I device
.SH DESCRIPTION
.B wipefs
-allows to erase filesystem or raid signatures (magic strings) from the
+can erase filesystem or raid signatures (magic strings) from the specified
.I device
to make the filesystem invisible for libblkid.
.B wipefs
-does not erase the whole filesystem or any other data from the device.
-When used without options -a or -o, it lists all visible filesystems and offsets
-of their signatures.
+does not erase the filesystem itself nor any other data from the device.
+When used without options \fB-a\fR or \fB-o\fR, it lists all visible filesystems
+and the offsets of their signatures.
.SH OPTIONS
.IP "\fB\-a, \-\-all\fP"
Erase all available signatures.
.IP "\fB\-n, \-\-no\-act\fP"
Causes everything to be done except for the write() call.
.IP "\fB\-o, \-\-offset\fP \fIoffset\fP
-Specifies location (in bytes) of the signature which should be erased from the
-device. The offset number may include a "0x" prefix, and then the number will be
-read as a hex value. It is possible to specify multiple -o options.
+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.
The \fIoffset\fR argument may be followed by binary (2^N) suffixes KiB, MiB,
GiB, TiB, PiB and EiB (the "iB" is optional, e.g. "K" has the same meaning as
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