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1 | .\" Copyright (c) 1980, 1989, 1991 The Regents of the University of California. |
2 | .\" All rights reserved. | |
3 | .\" | |
4 | .\" Redistribution and use in source and binary forms, with or without | |
5 | .\" modification, are permitted provided that the following conditions | |
6 | .\" are met: | |
7 | .\" 1. Redistributions of source code must retain the above copyright | |
8 | .\" notice, this list of conditions and the following disclaimer. | |
9 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
10 | .\" notice, this list of conditions and the following disclaimer in the | |
11 | .\" documentation and/or other materials provided with the distribution. | |
12 | .\" 3. All advertising materials mentioning features or use of this software | |
13 | .\" must display the following acknowledgement: | |
14 | .\" This product includes software developed by the University of | |
15 | .\" California, Berkeley and its contributors. | |
16 | .\" 4. Neither the name of the University nor the names of its contributors | |
17 | .\" may be used to endorse or promote products derived from this software | |
18 | .\" without specific prior written permission. | |
19 | .\" | |
20 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
21 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
22 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
23 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
24 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
25 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
26 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
27 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
28 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
29 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
30 | .\" SUCH DAMAGE. | |
31 | .\" | |
32 | .\" @(#)fstab.5 6.5 (Berkeley) 5/10/91 | |
33 | .\" | |
14160b7b | 34 | .TH FSTAB 5 "February 2015" "util-linux" "File Formats" |
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35 | .SH NAME |
36 | fstab \- static information about the filesystems | |
37 | .SH SYNOPSIS | |
46f057ed | 38 | .I /etc/fstab |
6dbe3af9 KZ |
39 | .SH DESCRIPTION |
40 | The file | |
b9f23bf7 | 41 | .B fstab |
14160b7b | 42 | contains descriptive information about the filesystems the system can mount. |
6dbe3af9 KZ |
43 | .B fstab |
44 | is only read by programs, and not written; it is the duty of the system | |
14160b7b | 45 | administrator to properly create and maintain this file. The order of records in |
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46 | .B fstab |
47 | is important because | |
2b6fc908 KZ |
48 | .BR fsck (8), |
49 | .BR mount (8), | |
3bd8d70c | 50 | and |
2b6fc908 | 51 | .BR umount (8) |
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52 | sequentially iterate through |
53 | .B fstab | |
54 | doing their thing. | |
55 | ||
14160b7b PC |
56 | Each filesystem is described on a separate line. |
57 | Fields on each line are separated by tabs or spaces. | |
58 | Lines starting with '#' are comments. Blank lines are ignored. | |
59 | .PP | |
60 | The following is a typical example of an | |
61 | .B fstab | |
62 | entry: | |
63 | .sp | |
64 | .RS 7 | |
65 | LABEL=t-home2 /home ext4 defaults,auto_da_alloc 0 2 | |
66 | .RE | |
67 | ||
abe3d704 KZ |
68 | .B The first field |
69 | .RI ( fs_spec ). | |
70 | .RS | |
f52eed86 KZ |
71 | This field describes the block special device, remote filesystem or filesystem |
72 | image for loop device to be mounted or swap file or swap partition to be enabled. | |
7eda085c | 73 | .LP |
14160b7b | 74 | For ordinary mounts, it will hold (a link to) a block special |
7eda085c | 75 | device node (as created by |
dbeb1d73 | 76 | .BR mknod (2)) |
7eda085c | 77 | for the device to be mounted, like `/dev/cdrom' or `/dev/sdb7'. |
14160b7b PC |
78 | For NFS mounts, this field is <host>:<dir>, e.g., `knuth.aeb.nl:/'. |
79 | For filesystems with no storage, any string can be used, and will show up in | |
80 | .BR df (1) | |
81 | output, for example. Typical usage is `proc' for procfs; `mem', `none', | |
82 | or `tmpfs' for tmpfs. Other special filesystems, like udev and sysfs, | |
83 | are typically not listed in | |
84 | .BR fstab . | |
7eda085c | 85 | .LP |
14160b7b PC |
86 | LABEL=<label> or UUID=<uuid> may be given instead of a device name. |
87 | This is the recommended method, as device names are often a coincidence | |
88 | of hardware detection order, and can change when other disks are added or removed. | |
89 | For example, `LABEL=Boot' or `UUID=3e6be9de\%-8139\%-11d1\%-9106\%-a43f08d823a6'. | |
90 | (Use a filesystem-specific tool like | |
91 | .BR e2label (8), | |
92 | .BR xfs_admin (8), | |
c07ebfa1 | 93 | or |
14160b7b PC |
94 | .BR fatlabel (8) |
95 | to set LABELs on filesystems). | |
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96 | |
97 | It's also possible to use PARTUUID= and PARTLABEL=. These partitions identifiers | |
71e87708 | 98 | are supported for example for GUID Partition Table (GPT). |
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99 | |
100 | See | |
71e87708 | 101 | .BR mount (8), |
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102 | .BR blkid (8) |
103 | or | |
104 | .BR lsblk (8) | |
14160b7b | 105 | for more details about device identifiers. |
3e90c89f | 106 | |
7c97f740 KZ |
107 | .LP |
108 | Note that | |
109 | .BR mount (8) | |
110 | uses UUIDs as strings. The string representation of the UUID should be based on | |
111 | lower case characters. | |
abe3d704 | 112 | .RE |
6dbe3af9 | 113 | |
abe3d704 KZ |
114 | .B The second field |
115 | .RI ( fs_file ). | |
116 | .RS | |
c768892f | 117 | This field describes the mount point (target) for the filesystem. For swap partitions, this |
7eda085c | 118 | field should be specified as `none'. If the name of the mount point |
6db1b1b1 AH |
119 | contains spaces or tabs these can be escaped as `\\040' and '\\011' |
120 | respectively. | |
abe3d704 | 121 | .RE |
6dbe3af9 | 122 | |
abe3d704 KZ |
123 | .B The third field |
124 | .RI ( fs_vfstype ). | |
125 | .RS | |
14160b7b PC |
126 | This field describes the type of the filesystem. Linux supports many |
127 | filesystem types: ext4, xfs, btrfs, f2fs, vfat, ntfs, hfsplus, | |
128 | tmpfs, sysfs, proc, iso9660, udf, squashfs, nfs, cifs, and many more. | |
129 | For more details, see | |
ffc43748 | 130 | .BR mount (8). |
abe3d704 | 131 | |
ffc43748 KZ |
132 | An entry |
133 | .I swap | |
134 | denotes a file or partition to be used | |
135 | for swapping, cf.\& | |
136 | .BR swapon (8). | |
137 | An entry | |
f92dc20f KZ |
138 | .I none |
139 | is useful for bind or move mounts. | |
6dbe3af9 | 140 | |
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141 | More than one type may be specified in a comma-separated list. |
142 | ||
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143 | .BR mount (8) |
144 | and | |
145 | .BR umount (8) | |
abe3d704 KZ |
146 | support filesystem |
147 | .IR subtypes . | |
148 | The subtype is defined by '.subtype' suffix. For | |
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149 | example 'fuse.sshfs'. It's recommended to use subtype notation rather than add |
150 | any prefix to the first fstab field (for example 'sshfs#example.com' is | |
208848ef | 151 | deprecated). |
abe3d704 | 152 | .RE |
e31597d8 | 153 | |
abe3d704 KZ |
154 | .B The fourth field |
155 | .RI ( fs_mntops ). | |
156 | .RS | |
157 | This field describes the mount options associated with the filesystem. | |
6dbe3af9 | 158 | |
14160b7b PC |
159 | It is formatted as a comma-separated list of options. |
160 | It contains at least the type of mount | |
161 | .RB ( ro | |
162 | or | |
163 | .BR rw ), | |
164 | plus any additional options appropriate to the filesystem | |
165 | type (including performance-tuning options). | |
166 | For details, see | |
167 | .BR mount (8) | |
168 | or | |
37f243ed KZ |
169 | .BR swapon (8). |
170 | ||
14160b7b | 171 | Basic filesystem-independent options are: |
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172 | .TP |
173 | .B defaults | |
174 | use default options: rw, suid, dev, exec, auto, nouser, and async. | |
175 | .TP | |
176 | .B noauto | |
1c4c6024 | 177 | do not mount when "mount \-a" is given (e.g., at boot time) |
abe3d704 KZ |
178 | .TP |
179 | .B user | |
180 | allow a user to mount | |
181 | .TP | |
182 | .B owner | |
183 | allow device owner to mount | |
184 | .TP | |
185 | .B comment | |
12b41eac KZ |
186 | or |
187 | .B x-<name> | |
abe3d704 KZ |
188 | for use by fstab-maintaining programs |
189 | .TP | |
190 | .B nofail | |
191 | do not report errors for this device if it does not exist. | |
192 | .RE | |
6dbe3af9 | 193 | |
abe3d704 KZ |
194 | .B The fifth field |
195 | .RI ( fs_freq ). | |
196 | .RS | |
14160b7b | 197 | This field is used by |
6dbe3af9 | 198 | .BR dump (8) |
14160b7b PC |
199 | to determine which filesystems need to be dumped. |
200 | Defaults to zero (don't dump) if not present. | |
abe3d704 | 201 | .RE |
6dbe3af9 | 202 | |
abe3d704 KZ |
203 | .B The sixth field |
204 | .RI ( fs_passno ). | |
205 | .RS | |
14160b7b | 206 | This field is used by |
6dbe3af9 | 207 | .BR fsck (8) |
14160b7b PC |
208 | to determine the order in which filesystem checks are done at |
209 | boot time. The root filesystem should be specified with a | |
6dbe3af9 | 210 | .I fs_passno |
14160b7b | 211 | of 1. Other filesystems should have a |
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212 | .I fs_passno |
213 | of 2. Filesystems within a drive will be checked sequentially, but | |
214 | filesystems on different drives will be checked at the same time to utilize | |
14160b7b PC |
215 | parallelism available in the hardware. |
216 | Defaults to zero (don't fsck) if not present. | |
85efb656 | 217 | .RE |
6dbe3af9 | 218 | |
67e63c12 MK |
219 | .SH FILES |
220 | .IR /etc/fstab , | |
221 | .I <fstab.h> | |
222 | ||
12b41eac | 223 | .SH NOTES |
6dbe3af9 KZ |
224 | The proper way to read records from |
225 | .B fstab | |
226 | is to use the routines | |
ca618233 KZ |
227 | .BR getmntent (3) |
228 | or | |
229 | .BR libmount . | |
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230 | |
231 | The keyword | |
232 | .B ignore | |
14160b7b | 233 | as a filesystem type (3rd field) is no longer supported by the pure |
12b41eac | 234 | libmount based mount utility (since util-linux v2.22). |
ade04bb8 MK |
235 | .SH HISTORY |
236 | The ancestor of this | |
237 | .B fstab | |
238 | file format appeared in 4.0BSD. | |
239 | .\" But without comment convention, and options and vfs_type. | |
5a829806 | 240 | .SH SEE ALSO |
f053ff1e MK |
241 | .BR getmntent (3), |
242 | .BR fs (5), | |
12b41eac | 243 | .BR findmnt (8), |
eb63b9b8 | 244 | .BR mount (8), |
f053ff1e | 245 | .BR swapon (8) |
ffc43748 | 246 | .\" Instead there was a type rw/ro/rq/sw/xx, where xx is the present 'ignore'. |
86d62711 | 247 | .SH AVAILABILITY |
601d12fb | 248 | This man page is part of the util-linux package and is available from |
d673b74e | 249 | https://www.kernel.org/pub/linux/utils/util-linux/. |