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1 | .\" Copyright 2000 Andreas Dilger (adilger@turbolinux.com) |
2 | .\" | |
3 | .\" This man page was created for blkid from e2fsprogs-1.25. | |
4 | .\" | |
5 | .\" This file may be copied under the terms of the GNU Public License. | |
6 | .\" | |
7 | .\" Based on uuidgen, Mon Sep 17 10:42:12 2000, Andreas Dilger | |
fc7a1669 | 8 | .TH BLKID 8 "February 2009" "Linux" "MAINTENANCE COMMANDS" |
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9 | .SH NAME |
10 | blkid \- command\-line utility to locate/print block device attributes | |
11 | .SH SYNOPSIS | |
12 | .B blkid | |
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13 | .RB \-L |
14 | .IR label " | " | |
15 | .RB \-U | |
16 | .IR uuid | |
17 | ||
18 | .B blkid | |
19 | .RB [ \-ghlv ] | |
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20 | .RB [ \-c |
21 | .IR file ] | |
22 | .RB [ \-w | |
23 | .IR file ] | |
24 | .RB [ \-o | |
25 | .IR format ] | |
26 | .in +6 | |
27 | .RB [ \-s | |
28 | .IR tag ] | |
29 | .RB [ \-t | |
30 | .IR NAME=value ] | |
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31 | [\fIdevice\fR ...] |
32 | .in -6 | |
33 | ||
34 | .B blkid | |
35 | .RB -p | |
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36 | .RB [ \-s |
37 | .IR tag ] | |
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38 | .RB [ \-O |
39 | .IR offset ] | |
40 | .RB [ \-S | |
41 | .IR size ] | |
42 | .RB [ \-o | |
43 | .IR format ] | |
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44 | .RB [ \-s |
45 | .IR tag ] | |
46 | .in +9 | |
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47 | .RB [ \-n |
48 | .IR list ] | |
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49 | .RB [ \-u |
50 | .IR list ] | |
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51 | .I device |
52 | [\fIdevice\fR ...] | |
53 | ||
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54 | .SH DESCRIPTION |
55 | The | |
56 | .B blkid | |
57 | program is the command-line interface to working with | |
58 | .BR libblkid (3) | |
59 | library. It can determine the type of content (e.g. filesystem, swap) | |
60 | a block device holds, and also attributes (tokens, NAME=value pairs) | |
61 | from the content metadata (e.g. LABEL or UUID fields). | |
62 | .PP | |
63 | .B blkid | |
64 | has two main forms of operation: either searching for a device with a | |
65 | specific NAME=value pair, or displaying NAME=value pairs for one or | |
66 | more devices. | |
67 | .SH OPTIONS | |
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68 | The \fIsize\fR and \fIoffset\fR arguments may be followed by binary (2^N) |
69 | suffixes KiB, MiB, GiB, TiB, PiB and EiB (the "iB" is optional, e.g. "K" has the | |
70 | same meaning as "KiB") or decimal (10^N) suffixes KB, MB, GB, PB and EB. | |
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71 | .TP |
72 | .BI \-c " cachefile" | |
73 | Read from | |
74 | .I cachefile | |
75 | instead of reading from the default cache file | |
76 | .IR /etc/blkid.tab . | |
77 | If you want to start with a clean cache (i.e. don't report devices previously | |
78 | scanned but not necessarily available at this time), specify | |
79 | .IR /dev/null . | |
80 | .TP | |
81 | .B \-g | |
82 | Perform a garbage collection pass on the blkid cache to remove | |
83 | devices which no longer exist. | |
84 | .TP | |
85 | .B \-h | |
86 | Display a usage message and exit. | |
87 | .TP | |
88 | .B \-l | |
89 | Look up one device that matches the search parameter specified using | |
90 | the | |
91 | .B \-t | |
92 | option. If there are multiple devices that match the specified search | |
93 | parameter, then the device with the highest priority is returned, and/or | |
94 | the first device found at a given priority. Device types in order of | |
95 | decreasing priority are Device Mapper, EVMS, LVM, MD, and finally regular | |
96 | block devices. If this option is not specified, | |
97 | .B blkid | |
98 | will print all of the devices that match the search parameter. | |
99 | .TP | |
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100 | .B \-L " label " |
101 | Look up one device that uses the label (same as: -l -o device -t | |
102 | LABEL=<label>). This look up method is able to reliable use /dev/disk/by-label | |
103 | udev symlinks (depends on setting in /etc/blkid.conf). Avoid to use the | |
104 | symlinks directly. It is not reliable to use the symlinks without verification. | |
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105 | The \fB-L\fR option works on systems with and without udev. |
106 | ||
107 | Unfortunately, the original | |
108 | .B blkid(8) | |
109 | from e2fsprogs use the \fB-L\fR option as a | |
110 | synonym to the \fB-o list\fR option. For better portability use "-l -o device | |
111 | -t LABEL=<label>" and "-o list" in your scripts rather than -L option. | |
fc7a1669 | 112 | .TP |
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113 | .B \-n " list " |
114 | Restrict probing functions to defined (comma separated) list of superblock types (names). | |
115 | The list can be prefixed with "no" to specify the types which should be ignored. | |
116 | For example: | |
117 | .sp | |
118 | blkid -p -n vfat,ext3,ext4 /dev/sda1 | |
119 | .sp | |
120 | probes for vfat, ext3 and ext4 filesystems, and | |
121 | .sp | |
122 | blkid -p -u nominix /dev/sda1 | |
123 | .sp | |
124 | probes for all supported formats exclude minix filesystem. This option is | |
125 | useful with | |
126 | \fB-p\fR only. | |
127 | .TP | |
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128 | .BI \-o " format" |
129 | Display | |
130 | .BR blkid 's | |
131 | output using the specified format. The | |
132 | .I format | |
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133 | parameter may be: |
134 | .RS | |
51410fc6 | 135 | .TP |
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136 | .B full |
137 | print all tags (the default) | |
138 | .TP | |
139 | .B value | |
140 | print the value of the tags | |
141 | .TP | |
142 | .B list | |
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143 | print the devices in a user-friendly format, this output format is unsupported |
144 | for low-level probing (\fB-p\fR) | |
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145 | .TP |
146 | .B device | |
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147 | print the device name only, this output format is always enabled for \fB-L\fR |
148 | and \fB-U\fR options | |
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149 | .TP |
150 | .B udev | |
151 | vol_id compatible mode; usable in udev rules | |
152 | .RE | |
153 | .TP | |
8ab912cf | 154 | .BI \-O " offset" |
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155 | Probe at the given offset (only useful with \fB-p\fR). |
156 | .TP | |
157 | .BI \-p | |
7711e215 | 158 | Switch to low-level probing mode (bypass cache) |
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159 | .TP |
160 | .BI \-s " tag" | |
161 | For each (specified) device, show only the tags that match | |
162 | .IR tag . | |
163 | It is possible to specify multiple | |
164 | .B \-s | |
165 | options. If no tag is specified, then all tokens are shown for all | |
166 | (specified) devices. | |
167 | In order to just refresh the cache without showing any tokens, use | |
168 | .B "-s none" | |
169 | with no other options. | |
170 | .TP | |
8ab912cf | 171 | .BI \-S " size" |
0bdd2f97 | 172 | Overwrite device/file size (only useful with \fB-p\fR). |
02a8a21a | 173 | .TP |
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174 | .BI \-t " NAME" = "value" |
175 | Search for block devices with tokens named | |
176 | .I NAME | |
177 | that have the value | |
178 | .IR value , | |
179 | and display any devices which are found. | |
180 | Common values for | |
181 | .I NAME | |
182 | include | |
183 | .BR TYPE , | |
184 | .BR LABEL , | |
185 | and | |
186 | .BR UUID . | |
187 | If there are no devices specified on the command line, all block devices | |
188 | will be searched; otherwise only the specified devices are searched. | |
189 | .TP | |
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190 | .B \-u " list " |
191 | Restrict probing functions to defined (comma separated) list of "usage" types. | |
192 | Supported usage types are: filesystem, raid, crypto and other. The list can be | |
193 | prefixed with "no" to specify the usage types which should be ignored. For example: | |
194 | .sp | |
195 | blkid -p -u filesystem,other /dev/sda1 | |
196 | .sp | |
197 | probes for all filesystems and others (e.g. swap) formats, and | |
198 | .sp | |
199 | blkid -p -u noraid /dev/sda1 | |
200 | .sp | |
201 | probes for all supported formats exclude RAIDs. This option is useful with | |
202 | \fB-p\fR only. | |
203 | .TP | |
204 | .B \-U " uuid " | |
205 | Look up one device that uses the uuid. For more details see the \fB-L\fR option. | |
206 | .TP | |
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207 | .B \-v |
208 | Display version number and exit. | |
209 | .TP | |
210 | .BI \-w " writecachefile" | |
211 | Write the device cache to | |
212 | .I writecachefile | |
213 | instead of writing it to the default cache file | |
214 | .IR /etc/blkid.tab . | |
215 | If you don't want to save the cache to the default file, specify | |
216 | .IR /dev/null. | |
217 | If not specified it will be the same file as that given by the | |
218 | .B \-c | |
219 | option. | |
220 | .TP | |
221 | .I device | |
222 | Display tokens from only the specified device. It is possible to | |
223 | give multiple | |
224 | .I device | |
225 | options on the command line. If none is given, all devices which | |
226 | appear in | |
227 | .I /proc/partitions | |
228 | are shown, if they are recognized. | |
229 | .SH "RETURN CODE" | |
230 | If the specified token was found, or if any tags were shown from (specified) | |
231 | devices, 0 is returned. If the specified token was not found, or no | |
232 | (specified) devices could be identified, an exit code of 2 is returned. | |
233 | For usage or other errors, an exit code of 4 is returned. | |
234 | .SH AUTHOR | |
235 | .B blkid | |
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236 | was written by Andreas Dilger for libblkid and improved by Theodore Ts'o |
237 | and Karel Zak. | |
51410fc6 | 238 | .SH AVAILABILITY |
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239 | The blkid command is part of the util-linux-ng package and is available from |
240 | ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/. | |
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241 | .SH "SEE ALSO" |
242 | .BR libblkid (3) | |
fc7a1669 | 243 | .BR findfs (8) |
c49057d2 | 244 | .BR wipefs (8) |