blkid

BLKID(8)							     BLKID(8)



NAME
       blkid - command-line utility to locate/print block device attributes

SYNOPSIS
       blkid  ]...   [ -h ] [ [ -c cachefile ] -s savecachefile ] [ -p ] [ -t
       token ]...  [ -v ] [ device ...	]

DESCRIPTION
       The blkid program is the command-line interface to working with	libu-
       uid(3)  library.	  It can determine the type of content (e.g. filesys-
       tem,  swap)  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 devices.

OPTIONS
       -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.

       -h     Display a usage message and exit.

       -p     Probe all available devices.  This is the default when display-
	      ing tokens.  When searching for a token normally the cache file
	      is used to locate the device and only that device is probed (to
	      ensure cache coherency) and all devices are probed only if  the
	      token cannot be found in the cache.

       -s     tag  tag	is  of the form NAME and the resulting token is shown
	      for each (specified) device that has such a tag.	It is  possi-
	      ble  to  specify multiple 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
	      -s none with no other options.

       -t     token token is of the form NAME=value and that  specific	token
	      is searched for in the cache or among all visible block devices
	      and additionally any specified devices.  If that token  is  not
	      found,  no  output  is  shown.   Common values for NAME include
	      TYPE, LABEL, and UUID.

       -v     Display version number and exit.

RETURN VALUE
       The  UUID  of  the   form   1b4e28ba-2fa1-11d2-883f-b9a761bde3fb	  (in
       printf(3)  format  "%08x-%04x-%04x-%04x-%012x") is output to the stan-
       dard output.

       -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 to the default file,	spec-
	      ify  /dev/null.	If  not specified it will be the same file as
	      that given by 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 return 2.  For
       usage or other errors return 4.

AUTHOR
       blkid was written by Andreas Dilger for libblkid.

AVAILABILITY
       blkid is part the e2fsprogs package since version 1.26 and  is  avail-
       able from http://e2fsprogs.sourceforge.net.

SEE ALSO
       libblkid(3)



E2fsprogs version 1.35		February 2004			     BLKID(8)