Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 1 | .\" Copyright 2001 Andreas Dilger (adilger@turbolinux.com) |
| 2 | .\" |
| 3 | .\" This man page was created for libblkid.so.1.0 from e2fsprogs-1.24. |
Benno Schulenberg | dcf051e | 2008-07-31 22:49:19 +0200 | [diff] [blame] | 4 | .\" |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 5 | .\" This file may be copied under the terms of the GNU Public License. |
Benno Schulenberg | dcf051e | 2008-07-31 22:49:19 +0200 | [diff] [blame] | 6 | .\" |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 7 | .\" Created Wed Sep 14 12:02:12 2001, Andreas Dilger |
| 8 | .TH LIBBLKID 3 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@" |
| 9 | .SH NAME |
| 10 | libblkid \- block device identification library |
| 11 | .SH SYNOPSIS |
| 12 | .B #include <blkid/blkid.h> |
| 13 | .sp |
| 14 | .B cc |
| 15 | .I file.c |
| 16 | .B \-lblkid |
| 17 | .SH DESCRIPTION |
| 18 | The |
| 19 | .B libblkid |
| 20 | library is used to identify block devices (disks) as to their content (e.g. |
| 21 | filesystem type) as well as extracting additional information such as |
| 22 | filesystem labels/volume names, unique identifiers/serial numbers, etc. |
| 23 | A common use is to allow use of LABEL= and UUID= tags instead of hard-coding |
| 24 | specific block device names into configuration files. |
| 25 | .P |
| 26 | Block device information is normally kept in a cache file |
| 27 | .I /etc/blkid.tab |
| 28 | and is verified to still be valid before being returned to the user |
| 29 | (if the user has read permission on the raw block device, otherwise not). |
| 30 | The cache file also allows unprivileged users (normally anyone other |
| 31 | than root, or those not in the "disk" group) to locate devices by label/id. |
Theodore Ts'o | 5010f29 | 2008-02-09 23:35:03 -0500 | [diff] [blame] | 32 | The standard location of the cache file can be overridden by the |
| 33 | environment variable BLKID_FILE. |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 34 | .P |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 35 | In situations where one is getting information about a single known device, |
| 36 | it does not impact performance whether the cache is used or not (unless you |
| 37 | are not able to read the block device directly). If you are dealing with |
Benno Schulenberg | dcf051e | 2008-07-31 22:49:19 +0200 | [diff] [blame] | 38 | multiple devices, use of the cache is highly recommended (even if empty) as |
| 39 | devices will be scanned at most one time and the on-disk cache will be |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 40 | updated if possible. There is rarely a reason not to use the cache. |
| 41 | .P |
| 42 | In some cases (modular kernels), block devices are not even visible until |
| 43 | after they are accessed the first time, so it is critical that there is |
| 44 | some way to locate these devices without enumerating only visible devices, |
| 45 | so the use of the cache file is |
| 46 | .B required |
| 47 | in this situation. |
| 48 | .SH AUTHOR |
| 49 | .B libblkid |
| 50 | was written by Andreas Dilger for the ext2 filesystem utilties, with input |
Theodore Ts'o | 2859522 | 2003-03-01 20:01:27 -0500 | [diff] [blame] | 51 | from Ted Ts'o. The library was subsequently heavily modified by Ted Ts'o. |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 52 | .SH FILES |
| 53 | .TP |
Benno Schulenberg | dcf051e | 2008-07-31 22:49:19 +0200 | [diff] [blame] | 54 | .I /etc/blkid.tab |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 55 | Caches data extracted from each recognized block device. |
| 56 | .SH AVAILABILITY |
| 57 | .B libblkid |
Theodore Ts'o | 2859522 | 2003-03-01 20:01:27 -0500 | [diff] [blame] | 58 | is part of the e2fsprogs package since version 1.33 and is available from |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 59 | http://e2fsprogs.sourceforge.net. |
| 60 | .SH COPYING |
| 61 | .B libblkid |
| 62 | is available under the terms of the GNU Library General Public License (LGPL), |
| 63 | version 2 (or at your discretion any later version). A copy of the LGPL |
| 64 | should be included with this library in the file COPYING. If not, write to |
| 65 | .RS |
| 66 | Free Software Foundation, Inc. |
| 67 | .br |
Benno Schulenberg | dcf051e | 2008-07-31 22:49:19 +0200 | [diff] [blame] | 68 | 51 Franklin St |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 69 | .br |
Benno Schulenberg | dcf051e | 2008-07-31 22:49:19 +0200 | [diff] [blame] | 70 | Fifth Floor |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 71 | .br |
Benno Schulenberg | dcf051e | 2008-07-31 22:49:19 +0200 | [diff] [blame] | 72 | Boston, MA 02110-1301 USA |
Theodore Ts'o | e12f2ae | 2003-01-23 16:45:16 -0500 | [diff] [blame] | 73 | .RE |
| 74 | .PP |
| 75 | or visit |
| 76 | .UR http://www.gnu.org/licenses/licenses.html#LGPL |
| 77 | http://www.gnu.org/licenses/licenses.html#LGPL |
| 78 | .UE |
| 79 | .SH "SEE ALSO" |
Benno Schulenberg | dcf051e | 2008-07-31 22:49:19 +0200 | [diff] [blame] | 80 | .BR blkid (8) |