libblkid

LIBBLKID(3)                    Programmer's Manual                   LIBBLKID(3)



NAME
       libblkid - block device identification library

SYNOPSIS
       #include <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
       identifiers/serial numbers. A common use is to allow use of LABEL= and
       UUID= tags instead of hard-coding specific block device names into
       configuration files.

       The low-level part of the library also allows the extraction of
       information about partitions and block device topology.

       The high-level part of the library keeps information about block devices
       in a cache file 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 (normally
       anyone other than root, or those not in the "disk" group) to locate
       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
       device, it does not impact performance whether the cache is used or not
       (unless you are not able to read the block device directly).

       The high-level part of the library supports two methods to evaluate
       LABEL/UUID. It reads information directly from a block device or read
       information from /dev/disk/by-* udev symlinks. The udev is preferred
       method by default.

       If you are dealing with multiple devices, use of the cache is highly
       recommended (even if empty) as devices will be scanned at most one time
       and the on-disk cache will be updated if possible.

       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 situation.

CONFIGURATION FILE
       The standard location of the /etc/blkid.conf config file can be
       overridden by the environment variable BLKID_CONF. For more details about
       the config file see blkid(8) man page.

AUTHORS
       libblkid was written by Andreas Dilger for the ext2 filesystem utilities,
       with input from Ted Ts’o. The library was subsequently heavily modified
       by Ted Ts’o.

       The low-level probing code was rewritten by Karel Zak.

COPYING
       libblkid is available under the terms of the GNU Library General Public
       License (LGPL), version 2 (or at your discretion any later version).

SEE ALSO
       blkid(8), findfs(8)

REPORTING BUGS
       For bug reports, use the issue tracker at
       https://github.com/karelzak/util-linux/issues.

AVAILABILITY
       The libblkid library is part of the util-linux package since version
       2.15. It can be downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>.



util-linux 2.37.2                  2021-06-02                        LIBBLKID(3)