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LIBBLKID(3)		   Library Functions Manual		   LIBBLKID(3)

NAME
       libblkid	- block	device identification library

SYNOPSIS
       #include	<blkid/blkid.h>

       cc file.c -lblkid

DESCRIPTION
       The  libblkid  library  is used to identify block devices (disks) as to
       their content (e.g.  filesystem type) as	well as	extracting  additional
       information  such  as  filesystem  labels/volume	 names,	unique identi-
       fiers/serial numbers, etc.  A common use	is to allow use	of LABEL=  and
       UUID= tags instead of hard-coding specific block	device names into con-
       figuration files.

       Block  device  information  is  normally	  kept	 in   a	  cache	  file
       /etc/blkid.tab  and is verified to still	be valid before	being returned
       to the user (if the user	has read permission on the raw	block  device,
       otherwise  not).	  The  cache file also allows unprivileged users (nor-
       mally anyone other than root, or	those not in the "disk"	group) to  lo-
       cate  devices by	label/id.  The standard	location of the	cache file can
       be overridden by	the environment	variable BLKID_FILE.

       In situations where one is getting information about a single known de-
       vice,  it  does not impact performance whether the cache	is used	or not
       (unless you are not able	to read	the block device  directly).   If  you
       are  dealing  with  multiple devices, use of the	cache is highly	recom-
       mended (even if empty) as devices will be scanned at most one time  and
       the  on-disk cache will be updated if possible.	There is rarely	a rea-
       son not to use the cache.

       In some cases (modular kernels),	block devices are not even visible un-
       til  after  they	 are  accessed	the first time,	so it is critical that
       there is	some way to locate these devices without enumerating only vis-
       ible  devices,  so the use of the cache file is required	in this	situa-
       tion.

AUTHOR
       libblkid	was written by Andreas Dilger for the ext2  filesystem	utili-
       ties,  with  input from Ted Ts'o.  The library was subsequently heavily
       modified	by Ted Ts'o.

FILES
       /etc/blkid.tab
	      Caches data extracted from each recognized block device.

AVAILABILITY
       libblkid	is part	of the e2fsprogs package since	version	 1.33  and  is
       available from http://e2fsprogs.sourceforge.net.

COPYING
       libblkid	is available under the terms of	the GNU	Library	General	Public
       License (LGPL), version 2 (or at	your discretion	any later version).  A
       copy of the LGPL	should be included with	this library in	the file COPY-
       ING.  If	not, write to
	      Free Software Foundation,	Inc.
	      51 Franklin St
	      Fifth Floor
	      Boston, MA  02110-1301  USA

       or	  visit		http://www.gnu.org/licenses/licenses.html#LGPL
       <http://www.gnu.org/licenses/licenses.html#LGPL>

SEE ALSO
       blkid(8)

E2fsprogs version 1.45.6	  March	2020			   LIBBLKID(3)

NAME | SYNOPSIS | DESCRIPTION | AUTHOR | FILES | AVAILABILITY | COPYING | SEE ALSO

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