Provided by: util-linux_2.27.1-6ubuntu3_amd64 bug


       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

       -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 udev.

              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_ prefixes

                     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 escaped.

       -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 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  -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

       -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


       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  from