blkid



BLKID(8)                                                              BLKID(8)




NAME

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


SYNOPSIS

       blkid  [  -hlv ] [ [ -c cachefile ] -w writecachefile ] [ -o format ] [
       -s tag ] [ -t NAME=value ] [ 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. filesystem,
       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     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 necessar-
              ily available at this time), specify /dev/null.

       -h     Display a usage message and exit.

       -l     Look up the device that matches the search  parameter  specified
              using  the  -t  option, assuming that there is only one matching
              the search parameter.  For a  system  with  a  large  number  of
              disks,  this  will  be  more  efficient  by avoiding the need to
              revalidate devices unless absolutely necessary.  If this  option
              is  not  specified,  blkid  will  use a less efficient approach,
              which allows blkid to print all of the devices  that  match  the
              search parameter.

              This option is best used for tag searches such as LABEL=data_vol
              or UUID=e280469a-d06f-4c0b-b068-44f3b576029e.  If you want blkid
              to  print  all  of the ext3 filesystems using a search parameter
              such as TYPE=ext3, then this option should not be used.

       -o     Display blkid’s output using the specified format.   The  format
              parameter  may  be  full,  (the default), value, (only print the
              value of any tags printed by blkid) or device  (only  print  the
              device name).

       -s     Show  only  the tags for each (specified) device 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.

       -t     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  search the devices specified by the
              user.

       -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 to the default file, specify
              /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 (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.


AUTHOR

       blkid was written by Andreas Dilger for libblkid.


AVAILABILITY

       blkid is part the e2fsprogs package since version 1.26 and is available
       from http://e2fsprogs.sourceforge.net.


SEE ALSO

       libblkid(3)



E2fsprogs version 1.38             June 2005                          BLKID(8)

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