Provided by: util-linux_2.20.1-1ubuntu3_i386 bug

NAME

       blkid - locate/print block device attributes

SYNOPSIS

       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 ...

DESCRIPTION

       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.

OPTIONS

       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
       EB.

       -c cachefile
              Read from cachefile instead of reading from  the  default  cache
              file  /etc/blkid.tab.   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  -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
              specified 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
              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
              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_
                     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.

              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

       -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
              partition table type (PTTYPE tag) and  partitions  (PART_ENTRY_*
              tags).

       -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-
              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 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/blkid.tab.  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.

RETURN CODE

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

AUTHOR

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

AVAILABILITY

       The  blkid  command  is part of the util-linux package and is available
       from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

SEE ALSO

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