blkid - locate/print block device attributes


   blkid -L label | -U uuid

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

   blkid -p [-O offset] [-o format] [-S size] [-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 the attributes
   (tokens, NAME=value pairs) from the content  metadata  (e.g.  LABEL  or
   UUID fields).

   It  is  recommended  to  use  lsblk(8) command to get information about
   block devices rather than blkid.  lsblk(8) provides  more  information,
   better  control  on  output  formatting  and  it  does not require root
   permissions to get actual information.

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

   Note  that  blkid  reads information directly from devices and for non-
   root users it returns cached unverified information.  It is  better  to
   use  lsblk  --fs  to  get  a  user-friendly overview of filesystems and
   devices.  lsblk(8) is also easy to use in  scripts.   blkid  is  mostly
   designed for system services and to test libblkid functionality.

   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 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.

   -c cachefile
          Read  from  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 /dev/null.

   -d     Don't   encode   non-printing   characters.    The  non-printing
          characters are encoded by ^ and M- notation  by  default.   Note
          that  the  -o udev output format uses a different encoding which
          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  information  about  I/O Limits (aka I/O topology).  The
          'export' output format is automatically  enabled.   This  option
          can be used together with the -p option.

   -k     List all known filesystems and RAIDs and exit.

   -l     Look  up  only  one  device  that  matches  the search parameter
          specified with the -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  filesystem  label;  this  is
          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

          Unfortunately, the original blkid(8) from e2fsprogs uses the  -L
          option as a synonym for -o list.  For better portability, 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-
          separated) 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
          Use  the  specified  output  format.   Note  that  the  order of
          variables and devices is not fixed.  See also  option  -s.   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).

                 This  output  format  is  DEPRECATED  in  favour  of  the
                 lsblk(8) command.

          device print  the device name only; this output format is always
                 enabled for the -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
                 partitions.  This output format is DEPRECATED.

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

                 The  non-printing  characters  are  encoded  by  ^ and M-
                 notation  and  all  potentially  unsafe  characters   are

   -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  (bypassing  the

          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  -p  (for  example  PART_ENTRY_UUID=  vs

   -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
          Override the size of device/file (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-
          separated)  list  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:

            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 filesystem uuid.  For more
          details see the -L option.

   -V     Display version number and exit.


   If the specified device or device addressed by specified token  (option
   -t)  was  found  and  it's possible to gather any information about the
   device, an exit code 0 is returned.  Note the option -s filters  output
   tags, but it does not affect return code.

   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 an ambivalent low-level probing result was detected, an exit code of
   8 is returned.


   The  standard  location  of  the  /etc/blkid.conf  config  file  can be
   overridden by  the  environment  variable  BLKID_CONF.   The  following
   options control the libblkid library:

          Sends  uevent when /dev/disk/by-{label,uuid,partuuid,partlabel}/
          symlink does not match with LABEL, UUID, PARTUUID  or  PARTLABEL
          on the device.  Default is "yes".

          Overrides the standard location of the cache file.  This setting
          can  be  overridden  by  the  environment  variable  BLKID_FILE.
          Default  is  /run/blkid/,  or /etc/ on systems
          without a /run directory.

          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
          /dev/disk/by-* symlinks and the "scan" method  scans  all  block
          devices from the /proc/partitions file.


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


   Setting LIBBLKID_DEBUG=all enables debug output.


   libblkid(3), findfs(8), wipefs(8), lsblk(8),


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

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