libblkid

LIBBLKID(3)							  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
       configuration 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
       locate devices by label/id.

       In  situations  where  one is getting information about a single known
       device, 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	 rec-
       ommended	 (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
       reason not to use the cache.

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

AUTHOR
       libblkid	 was  written by Andreas Dilger for the ext2 filesystem util-
       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	 Pub-
       lic  License  (LGPL),  version 2 (or at your discretion any later ver-
       sion).  A copy of the LGPL should be included with this library in the
       file COPYING.  If not, write to
	      Free Software Foundation, Inc.
	      59 Temple Place
	      Suite 330
	      Boston, MA  02111-1307  USA

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

SEE ALSO
       blkid_get_cache(3),	  blkid_put_cache(3),	    blkid_get_dev(3),
       blkid_probe_all(3),   blkid_get_devname(3),    blkid_get_tag_value(3),
       blkid.tab(7)



E2fsprogs version 1.35		February 2004			  LIBBLKID(3)