mirror of https://github.com/vitalif/e2fsprogs
97 lines
3.4 KiB
Groff
97 lines
3.4 KiB
Groff
.\" Copyright 2001 Andreas Dilger (adilger@turbolinux.com)
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.\"
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.\" This man page was created for libblkid.so.1.0 from e2fsprogs-1.24.
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.\"
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.\" This file may be copied under the terms of the GNU Public License.
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.\"
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.\" Created Wed Sep 14 12:02:12 2001, Andreas Dilger
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.TH LIBBLKID 3 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
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.SH NAME
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libblkid \- block device identification library
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.SH SYNOPSIS
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.B #include <blkid/blkid.h>
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.sp
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.B cc
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.I file.c
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.B \-lblkid
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.SH DESCRIPTION
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The
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.B libblkid
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library is used to identify block devices (disks) as to their content (e.g.
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filesystem type) as well as extracting additional information such as
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filesystem labels/volume names, unique identifiers/serial numbers, etc.
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A common use is to allow use of LABEL= and UUID= tags instead of hard-coding
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specific block device names into configuration files.
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.P
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Block device information is normally kept in a cache file
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.I /etc/blkid.tab
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and is verified to still be valid before being returned to the user
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(if the user has read permission on the raw block device, otherwise not).
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The cache file also allows unprivileged users (normally anyone other
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than root, or those not in the "disk" group) to locate devices by label/id.
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.P
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Functions with "get" in their name will first search the cache (if given)
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for the specified data, and failing that will search visible block devices
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for this information. Functions with "find" in their name will only search
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the existing cache data for the specified device.
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.P
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In situations where one is getting information about a single known device,
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it does not impact performance whether the cache is used or not (unless you
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are not able to read the block device directly). If you are dealing with
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multiple devices use of the cache is highly recommended (even if empty) as
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devices will be scanned at most one time, and the on-disk cache will be
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updated if possible. There is rarely a reason not to use the cache.
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.P
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In some cases (modular kernels), block devices are not even visible until
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after they are accessed the first time, so it is critical that there is
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some way to locate these devices without enumerating only visible devices,
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so the use of the cache file is
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.B required
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in this situation.
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.SH AUTHOR
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.B libblkid
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was written by Andreas Dilger for the ext2 filesystem utilties, with input
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from Ted Ts'o.
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.SH FILES
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.TP
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.I /etc/blkid.tab
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Caches data extracted from each recognized block device.
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.SH AVAILABILITY
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.B libblkid
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is part of the e2fsprogs package since version 1.25 and is available from
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http://e2fsprogs.sourceforge.net.
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.SH COPYING
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.B libblkid
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is available under the terms of the GNU Library General Public License (LGPL),
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version 2 (or at your discretion any later version). A copy of the LGPL
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should be included with this library in the file COPYING. If not, write to
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.RS
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Free Software Foundation, Inc.
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.br
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59 Temple Place
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.br
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Suite 330
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.br
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Boston, MA 02111-1307 USA
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.RE
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.PP
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or visit
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.UR http://www.gnu.org/licenses/licenses.html#LGPL
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http://www.gnu.org/licenses/licenses.html#LGPL
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.UE
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.SH "SEE ALSO"
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.BR blkid_read_cache (3),
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.BR blkid_save_cache (3),
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.BR blkid_free_cache (3),
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.BR blkid_get_devname (3),
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.BR blkid_get_devno (3),
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.BR blkid_probe_all (3),
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.BR blkid_token_to_tag (3),
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.BR blkid_free_dev (3),
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.BR blkid_find_tag_dev (3),
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.BR blkid_find_tag_cache (3),
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.BR blkid_get_tag_cache (3),
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.BR blkid_get_tagname_devname (3),
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.BR blkid_get_token (3),
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.BR blkid.tab (7)
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