+++ /dev/null
-.\" Copyright 2000 Andreas Dilger (adilger@turbolinux.com)
-.\"
-.\" This file may be copied under the terms of the GNU Public License.
-.TH BLKID 8 "March 2013" "util-linux" "System Administration"
-.SH NAME
-blkid \- locate/print block device attributes
-.SH SYNOPSIS
-.IP \fBblkid\fR
-.BI \-\-label " label"
-|
-.BI \-\-uuid " uuid"
-
-.IP \fBblkid\fR
-.RB [ \-\-no\-encoding
-.B \-\-garbage\-collect \-\-list\-one \-\-cache\-file
-.IR file ]
-.RB [ \-\-output
-.IR format ]
-.RB [ \-\-match\-tag
-.IR tag ]
-.RB [ \-\-match\-token
-.IR NAME=value ]
-.RI [ device " ...]"
-
-.IP \fBblkid\fR
-.BR \-\-probe " [" \-\-offset
-.IR offset ]
-.RB [ \-\-output
-.IR format ]
-.RB [ \-\-size
-.IR size ]
-.RB [ \-\-match\-tag
-.IR tag ]
-.RB [ \-\-match\-types
-.IR list ]
-.RB [ \-\-usages
-.IR list ]
-.RB [ \-\-no\-part\-details ]
-.IR device " ..."
-
-.IP \fBblkid\fR
-.BR \-\-info " [" \-\-output
-.IR format ]
-.RB [ \-\-match\-tag
-.IR tag ]
-.IR device " ..."
-
-.SH DESCRIPTION
-The
-.B blkid
-program is the command-line interface to working with the
-.BR libblkid (3)
-library. It can determine the type of content (e.g. filesystem or swap)
-that a block device holds, and also the attributes (tokens, NAME=value pairs)
-from the content metadata (e.g. LABEL or UUID fields).
-.PP
-.B It is recommended to use
-.BR lsblk (8)
-.B command to get information about block devices, or lsblk --fs to get an overview of filesystems, or
-.BR findmnt (8)
-.B to search in already mounted filesystems.
-.PP
-.RS
-.BR lsblk (8)
-provides more information, better control on output formatting, easy to use in
-scripts and it does not require root permissions to get actual information.
-.B blkid
-reads information directly from devices and for non-root users
-it returns cached unverified information.
-.B blkid
-is mostly designed for system services and to test libblkid functionality.
-.RE
-
-.PP
-When
-.I device
-is specified, tokens from only this device are displayed.
-It is possible to specify multiple
-.I device
-arguments on the command line.
-If none is given, all partitions or unpartitioned devices which appear in
-.I /proc/partitions
-are shown, if they are recognized.
-.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 specified devices.
-
-For security reasons
-.B blkid
-silently ignores all devices where the probing result is ambivalent (multiple
-colliding filesystems are detected). The low-level probing mode (\fB-p\fR)
-provides more information and extra return code in this case.
-It's recommended to use
-.BR wipefs (8)
-to get a detailed overview and to erase obsolete stuff (magic strings) from the device.
-
-.SH OPTIONS
-The \fIsize\fR and \fIoffset\fR arguments may be followed by the multiplicative
-suffixes like 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
-\fB\-c\fR, \fB\-\-cache\-file\fR \fIcachefile\fR
-Read from
-.I cachefile
-instead of reading from the default cache file (see the CONFIGURATION FILE section
-for more details). If you want to start with a clean cache (i.e. don't report
-devices previously scanned but not necessarily available at this time), specify
-.IR /dev/null .
-.TP
-\fB\-d\fR, \fB\-\-no\-encoding\fR
-Don't encode non-printing characters. The non-printing characters are encoded
-by ^ and M- notation by default. Note that the \fB\-\-output udev\fR output format uses
-a different encoding which cannot be disabled.
-.TP
-\fB\-D\fR, \fB\-\-no\-part\-details\fR
-Don't print information (PART_ENTRY_* tags) from partition table in low-level probing mode.
-.TP
-\fB\-g\fR, \fB\-\-garbage\-collect\fR
-Perform a garbage collection pass on the blkid cache to remove
-devices which no longer exist.
-.TP
-\fB\-h\fR, \fB\-\-help\fR
-Display a usage message and exit.
-.TP
-\fB\-i\fR, \fB\-\-info\fR
-Display information about I/O Limits (aka I/O topology). The 'export' output format is
-automatically enabled. This option can be used together with the \fB\-\-probe\fR option.
-.TP
-\fB\-k\fR, \fB\-\-list\-filesystems\fR
-List all known filesystems and RAIDs and exit.
-.TP
-\fB\-l\fR, \fB\-\-list\-one\fR
-Look up only one device that matches the search parameter specified with the \fB\-\-match\-token\fR
-option. If there are multiple devices that match the specified search
-parameter, then the device with the highest priority is returned, and/or
-the first device found at a given priority (but see below note about udev).
-Device types in order of decreasing priority are: Device Mapper, EVMS, LVM, MD,
-and finally regular block devices. If this option is not specified,
-.B blkid
-will print all of the devices that match the search parameter.
-.sp
-This option forces
-.B blkid
-to use udev when used for LABEL or UUID tokens in \fB\-\-match\-token\fR. The
-goal is to provide output consistent with another utils (like mount, etc.)
-on systems where the same tag is used for multiple devices.
-.TP
-\fB\-L\fR, \fB\-\-label\fR \fIlabel\fR
-Look up the device that uses this filesystem \fIlabel\fR; this is equal to
-.BR "--list-one --output device --match-token LABEL=\fIlabel\fR" .
-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-\-label\fR option works on systems with and without udev.
-
-Unfortunately, the original
-.BR blkid (8)
-from e2fsprogs uses the \fB-L\fR option as a
-synonym for \fB-o list\fR. For better portability, use \fB-l -o device
--t LABEL=\fIlabel\fR and \fB-o list\fR in your scripts rather than the \fB-L\fR option.
-.TP
-\fB\-n\fR, \fB\-\-match\-types\fR \fIlist\fR
-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 --probe --match-types vfat,ext3,ext4 /dev/sda1
-.sp
-probes for vfat, ext3 and ext4 filesystems, and
-.sp
- blkid --probe --match-types nominix /dev/sda1
-.sp
-probes for all supported formats except minix filesystems.
-This option is only useful together with \fB\-\-probe\fR.
-.TP
-\fB\-o\fR, \fB\-\-output\fR \fIformat\fR
-Use the specified output format. Note that the order of variables and
-devices is not fixed. See also option \fB-s\fR. The
-.I format
-parameter may be:
-.RS
-.TP
-.B full
-print all tags (the default)
-.TP
-.B value
-print the value of the tags
-.TP
-.B list
-print the devices in a user-friendly format; this output format is unsupported
-for low-level probing (\fB\-\-probe\fR or \fB\-\-info\fR).
-
-This output format is \fBDEPRECATED\fR in favour of the
-.BR lsblk (8)
-command.
-.TP
-.B device
-print the device name only; this output format is always enabled for the \fB\-\-label\fR
-and \fB\-\-uuid\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. The value may be modified to be
-safe for udev environment; allowed is plain ASCII, hex-escaping and valid UTF-8,
-everything else (including whitespaces) is replaced with '_'. The keys with
-_ENC postfix use hex-escaping for unsafe chars.
-
-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.
-
-This output format is \fBDEPRECATED\fR.
-.TP
-.B export
-print key=value pairs for easy import into the environment; this output format
-is automatically enabled when I/O Limits (\fB\-\-info\fR option) are requested.
-
-The non-printing characters are encoded by ^ and M- notation and all
-potentially unsafe characters are escaped.
-.RE
-.TP
-\fB\-O\fR, \fB\-\-offset\fR \fIoffset\fR
-Probe at the given \fIoffset\fR (only useful with \fB\-\-probe\fR). This option can be
-used together with the \fB\-\-info\fR option.
-.TP
-\fB\-p\fR, \fB\-\-probe\fR
-Switch to low-level superblock probing mode (bypassing the cache).
-
-Note that low-level probing also returns information about partition table type
-(PTTYPE tag) and partitions (PART_ENTRY_* tags). The tag names produced by
-low-level probing are based on names used internally by libblkid and it may be
-different than when executed without \fB\-\-probe\fR (for example PART_ENTRY_UUID= vs
-PARTUUID=). See also \fB\-\-no\-part\-details\fR.
-.TP
-\fB\-s\fR, \fB\-\-match\-tag\fR \fItag\fR
-For each (specified) device, show only the tags that match
-.IR tag .
-It is possible to specify multiple
-.B \-\-match\-tag
-options. If no tag is specified, then all tokens are shown for all
-(specified) devices.
-In order to just refresh the cache without showing any tokens, use
-.B "\-\-match\-tag none"
-with no other options.
-.TP
-\fB\-S\fR, \fB\-\-size\fR \fIsize\fR
-Override the size of device/file (only useful with \fB\-\-probe\fR).
-.TP
-\fB\-t\fR, \fB\-\-match\-token\fR \fINAME=value\fR
-Search for block devices with tokens named
-.I NAME
-that have the value
-.IR value ,
-and display any devices which are found.
-Common values for
-.I NAME
-include
-.BR TYPE ,
-.BR LABEL ,
-and
-.BR UUID .
-If there are no devices specified on the command line, all block devices
-will be searched; otherwise only the specified devices are searched.
-.TP
-\fB\-u\fR, \fB\-\-usages\fR \fIlist\fR
-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 --probe --usages filesystem,other /dev/sda1
-.sp
-probes for all filesystem and other (e.g. swap) formats, and
-.sp
- blkid --probe --usages noraid /dev/sda1
-.sp
-probes for all supported formats except RAIDs.
-This option is only useful together with \fB\-\-probe\fR.
-.TP
-\fB\-U\fR, \fB\-\-uuid\fR \fIuuid\fR
-Look up the device that uses this filesystem \fIuuid\fR. For more details see the
-\fB\-\-label\fR option.
-.TP
-\fB\-V\fR, \fB\-\-version\fR
-Display version number and exit.
-.SH "RETURN CODE"
-If the specified device or device addressed by specified token (option
-\fB\-\-match\-token\fR) was found and it's possible to gather any information about the
-device, an exit code 0 is returned. Note the option \fB\-\-match\-tag\fR filters output
-tags, but it does not affect return code.
-
-If the specified token was not found, or no (specified) devices could be
-identified, or it is impossible to gather any information about the device
-identifiers or device content an exit code of 2 is returned.
-
-For usage or other errors, an exit code of 4 is returned.
-
-If an ambivalent probing result was detected by low-level probing mode (\fB\-p\fR), an exit code of 8 is
-returned.
-.SH CONFIGURATION FILE
-The standard location of the
-.I /etc/blkid.conf
-config file can be overridden by the environment variable BLKID_CONF.
-The following options control the libblkid library:
-.TP
-.I SEND_UEVENT=<yes|not>
-Sends uevent when
-.I /dev/disk/by-{label,uuid,partuuid,partlabel}/
-symlink does not match with LABEL, UUID, PARTUUID or PARTLABEL on the device. Default is "yes".
-.TP
-.I CACHE_FILE=<path>
-Overrides the standard location of the cache file. This setting can be
-overridden by the environment variable BLKID_FILE. Default is
-.IR /run/blkid/blkid.tab ,
-or
-.I /etc/blkid.tab
-on systems without a /run directory.
-.TP
-.I EVALUATE=<methods>
-Defines LABEL and UUID evaluation method(s). Currently, the libblkid library
-supports the "udev" and "scan" methods. More than one method may be specified in
-a comma-separated list. Default is "udev,scan". The "udev" method uses udev
-.I /dev/disk/by-*
-symlinks and the "scan" method scans all block devices from the
-.I /proc/partitions
-file.
-.SH AUTHOR
-.B blkid
-was written by Andreas Dilger for libblkid and improved by Theodore Ts'o
-and Karel Zak.
-.SH ENVIRONMENT
-.IP "Setting LIBBLKID_DEBUG=all enables debug output."
-.SH SEE ALSO
-.BR libblkid (3),
-.BR findfs (8),
-.BR lsblk (8),
-.BR wipefs (8)
-.SH AVAILABILITY
-The blkid command is part of the util-linux package and is available from
-https://www.kernel.org/pub/linux/utils/util-linux/.
projects / thirdparty / util-linux.git / blobdiff