blkid man page on ElementaryOS

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BLKID(8)		     System Administration		      BLKID(8)

       blkid - locate/print block device attributes

       blkid -L label | -U uuid

       blkid [-dghlv] [-c file] [-w file] [-o format]
	     [-s tag] [-t NAME=value] [device ...]

       blkid -p [-O offset] [-S size] [-o format] [-s tag]
		[-n list] [-u list] device ...

       blkid -i [-o format] [-s tag] device ...

       The  blkid  program  is	the command-line interface to working with the
       libblkid(3) 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).

       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.

       The  size and offset 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
       same  meaning  as  "KiB") or decimal (10^N) suffixes KB, MB, GB, PB and

       -c cachefile
	      Read from cachefile instead of reading from  the	default	 cache
	      file  /etc/   If  you want to start with a clean cache
	      (i.e. don't report devices previously scanned but not  necessar‐
	      ily available at this time), specify /dev/null.

       -d     Don't  encode  non-printing characters. The non-printing charac‐
	      ters are encoded by ^ and M- notation by default. Note  that  -o
	      udev  output  format  uses a diffrent encoding and this encoding
	      cannot be disabled.

       -g     Perform a garbage collection pass on the blkid cache  to	remove
	      devices which no longer exist.

       -h     Display a usage message and exit.

       -i     Display I/O Limits (aka I/O topology) information.  The 'export'
	      output format is automatically enabled.  This option can be used
	      together with the -p option.

       -l     Look up only one device that matches the search parameter speci‐
	      fied with -t.

       -k     List all known filesystems and RAIDs and exit.

       -t     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.
	      Device  types in order of decreasing priority are Device Mapper,
	      EVMS, LVM, MD, and  finally  regular  block  devices.   If  this
	      option  is  not  specified,  blkid will print all of the devices
	      that match the search parameter.

       -L label
	      Look up the device that uses this label (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  -L
	      option works on systems with and without udev.

	      Unfortunately,  the  original blkid(8) from e2fsprogs use the -L
	      option as a synonym for the -o list option.  For	better	porta‐
	      bility,  use  -l	-o device -t LABEL=<label> and -o list in your
	      scripts rather than the -L option.

       -n list
	      Restrict the probing functions  to  the  specified  (comma-sepa‐
	      rated)  list of superblock types (names).	 The list items may be
	      prefixed with "no" to specify the types which should be ignored.
	      For example:

		blkid -p -n vfat,ext3,ext4 /dev/sda1

	      probes for vfat, ext3 and ext4 filesystems, and

		blkid -p -n nominix /dev/sda1

	      probes for all supported formats except minix filesystems.  This
	      option is only useful together with -p.

       -o format
	      Display blkid's output using the specified format.   The	format
	      parameter may be:

	      full   print all tags (the default)

	      value  print the value of the tags

	      list   print  the devices in a user-friendly format; this output
		     format is unsupported for low-level probing (-p or -i)

	      device print the device name only; this output format is	always
		     enabled for -L and -U options

	      udev   print  key="value"	 pairs	for  easy import into the udev
		     environment; the keys are prefixed by ID_FS_ or  ID_PART_

		     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 parti‐

	      export print key=value pairs for easy import into	 the  environ‐
		     ment;  this  output  format is automatically enabled when
		     I/O Limits (-i option) are requested

       -O offset
	      Probe at the given offset (only useful with  -p).	  This	option
	      can be used together with the -i option.

       -p     Switch to low-level superblock probing mode (bypass cache).

	      Note  that low-level probing also returns information about par‐
	      tition table type	 (PTTYPE  tag)	and  partitions	 (PART_ENTRY_*

       -s tag For  each (specified) device, show only the tags that match tag.
	      It is possible to specify multiple -s 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 -s none with no other options.

       -S size
	      Overwrite device/file size (only useful with -p).

       -t NAME=value
	      Search  for  block  devices with tokens named NAME that have the
	      value value, and display any devices which  are  found.	Common
	      values  for NAME include TYPE, LABEL, and UUID.  If there are no
	      devices specified on the command line, all block devices will be
	      searched; otherwise only the specified devices are searched.

       -u list
	      Restrict	the  probing  functions	 to the specified (comma-sepa‐
	      rated) list  of  "usage"	types.	 Supported  usage  types  are:
	      filesystem,  raid, crypto and other.  The list items may be pre‐
	      fixed with "no" to specify  the  usage  types  which  should  be
	      ignored.	For example:

		blkid -p -u filesystem,other /dev/sda1

	      probes for all filesystem and other (e.g. swap) formats, and

		blkid -p -u noraid /dev/sda1

	      probes  for  all supported formats except RAIDs.	This option is
	      only useful together with -p.

       -U uuid
	      Look up the device that uses this uuid.  For  more  details  see
	      the -L option.

       -v     Display version number and exit.

       -w writecachefile
	      Write  the  device cache to writecachefile instead of writing it
	      to the default cache file /etc/	 If you don't want  to
	      save  the cache at all, specify /dev/null.  If not specified, it
	      will be the same file as that given with the -c option.

       device Display tokens from only the specified device.  It  is  possible
	      to give multiple device options on the command line.  If none is
	      given, all devices which appear in /proc/partitions  are	shown,
	      if they are recognized.

       If the specified token was found, or if any tags were shown from (spec‐
       ified) 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.

       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 returned.

       blkid was written by  Andreas  Dilger  for  libblkid  and  improved  by
       Theodore Ts'o and Karel Zak.

       The  blkid  command  is part of the util-linux package and is available

       libblkid(3) findfs(8) wipefs(8)

util-linux			 February 2011			      BLKID(8)

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