1.\" $OpenBSD: fstab.5,v 1.42 2009/06/08 17:03:15 jmc Exp $ 2.\" $NetBSD: fstab.5,v 1.5.2.1 1995/11/16 20:11:11 pk Exp $ 3.\" 4.\" Copyright (c) 1980, 1989, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)fstab.5 8.1 (Berkeley) 6/5/93 32.\" 33.Dd $Mdocdate: June 8 2009 $ 34.Dt FSTAB 5 35.Os 36.Sh NAME 37.Nm fstab 38.Nd static information about the filesystems 39.Sh SYNOPSIS 40.Fd #include <fstab.h> 41.Sh DESCRIPTION 42The 43.Nm 44file contains descriptive information about the various file systems. 45.Nm 46is only read by programs, and not written; 47it is the duty of the system administrator to properly create 48and maintain this file. 49Each filesystem is described on a separate line; 50fields on each line are separated by tabs or spaces. 51Lines beginning with the 52.Sq # 53character are comments and are ignored. 54The order of records in 55.Nm 56is important because 57.Xr fsck 8 58and 59.Xr mount 8 60sequentially iterate through 61.Nm 62doing their thing. 63.Pp 64A line has the following format: 65.Bd -literal -offset indent 66fs_spec fs_file fs_vfstype fs_mntops fs_freq fs_passno 67.Ed 68.Pp 69The first field, 70.Fa fs_spec , 71describes the block special device or remote filesystem to be mounted. 72For filesystems of type ffs 73.Pq Xr mount_ffs 8 , 74the special file name is the block special file name, 75and not the character special file name. 76For filesystems of type mfs 77.Pq Xr mount_mfs 8 , 78the special file name is typically that of the primary swap area; 79if the keyword 80.Dq swap 81is used instead of a special file name, 82default configuration parameters are used. 83If a program needs the character special file name, 84the program must create it by appending an 85.Dq r 86after the last 87.Dq / 88in the special file name. 89.Pp 90The second field, 91.Fa fs_file , 92describes the mount point for the filesystem. 93For swap partitions, this field should be specified as 94.Dq none . 95.Pp 96The third field, 97.Fa fs_vfstype , 98describes the type of the filesystem. 99The system currently supports the following types of filesystems: 100.Pp 101.Bl -tag -width indent -offset indent -compact 102.It cd9660 103An ISO 9660 CD-ROM filesystem. 104.It ext2fs 105A local Linux compatible ext2fs 106filesystem. 107.It ffs 108A local 109.Ux 110filesystem. 111.It mfs 112A local memory-based 113.Ux 114filesystem. 115.It msdos 116An 117.Tn MS-DOS 118FAT filesystem. 119.It nfs 120A Sun Microsystems compatible Network File System. 121.It ntfs 122An NTFS filesystem. 123.It procfs 124A local filesystem containing process information. 125.It swap 126A disk partition to be used for swapping. 127.It udf 128A UDF filesystem. 129.It vnd 130A VND image file. 131.El 132.Pp 133The fourth field, 134.Fa fs_mntops , 135describes the mount options associated with the filesystem. 136It is formatted as a comma separated list of options. 137It contains at least the type of mount (see 138.Fa fs_type 139below) plus any additional options appropriate to the filesystem type. 140.Pp 141The option 142.Dq auto 143can be used in the 144.Dq noauto 145form to cause 146a file system not to be mounted automatically (with 147.Ic mount -A 148or 149.Ic mount -a , 150or at system boot time). 151.Pp 152If the options 153.Dq userquota 154and/or 155.Dq groupquota 156are specified, the filesystem is automatically processed by the 157.Xr quotacheck 8 158command, and user and/or group disk quotas are enabled with 159.Xr quotaon 8 . 160By default, filesystem quotas are maintained in files named 161.Pa quota.user 162and 163.Pa quota.group 164which are located at the root of the associated filesystem. 165These defaults may be overridden by putting an equal sign 166and an alternative absolute pathname following the quota option. 167Thus, if the user quota file for 168.Pa /tmp 169is stored in 170.Pa /var/quotas/tmp.user , 171this location can be specified as: 172.Bd -literal -offset indent 173userquota=/var/quotas/tmp.user 174.Ed 175.Pp 176The type of the mount is extracted from the first parameter of the 177.Fa fs_mntops 178field and stored separately in the 179.Fa fs_type 180field (it is not deleted from the 181.Fa fs_mntops 182field). 183If 184.Fa fs_type 185is 186.Dq rw 187or 188.Dq ro 189then the filesystem whose name is given in the 190.Fa fs_file 191field is normally mounted read-write or read-only on the 192specified special file. 193If 194.Fa fs_type 195is 196.Dq sw 197then the special file is made available as a piece of swap space by the 198.Xr swapon 8 199command at the end of the system reboot procedure. 200The fields other than 201.Fa fs_spec 202and 203.Fa fs_type 204are unused. 205If 206.Fa fs_type 207is specified as 208.Dq xx 209the entry is ignored. 210This is useful to show disk partitions which are currently unused. 211.Pp 212The fifth field, 213.Fa fs_freq , 214is used by the 215.Fl W 216and 217.Fl w 218options of 219.Xr dump 8 220to recommend which filesystems should be backed up. 221The value specifies the number of days 222after which a dump is regarded as being old; 223if it is not present, a value of zero is returned and 224.Xr dump 8 225will assume that the filesystem does not need to be dumped. 226.Pp 227The sixth field, 228.Fa fs_passno , 229is used by the 230.Xr fsck 8 231program to determine the order in which filesystem checks are done 232at reboot time. 233The root filesystem should be specified with a 234.Fa fs_passno 235of 1, and other filesystems should have a 236.Fa fs_passno 237of 2. 238Filesystems within a drive will be checked sequentially, 239but filesystems on different drives will be checked at the 240same time to utilize parallelism available in the hardware. 241If the sixth field is not present or is zero, 242a value of zero is returned and 243.Xr fsck 8 244will assume that the filesystem does not need to be checked. 245.Bd -literal 246#define FSTAB_RW "rw" /* read-write device */ 247#define FSTAB_RO "ro" /* read-only device */ 248#define FSTAB_SW "sw" /* swap device */ 249#define FSTAB_XX "xx" /* ignore totally */ 250 251struct fstab { 252 char *fs_spec; /* block special device name */ 253 char *fs_file; /* filesystem path prefix */ 254 char *fs_vfstype; /* type of filesystem */ 255 char *fs_mntops; /* comma separated mount options */ 256 char *fs_type; /* rw, ro, sw, or xx */ 257 int fs_freq; /* dump frequency, in days */ 258 int fs_passno; /* pass number on parallel fsck */ 259}; 260.Ed 261.Pp 262The proper way to read records from 263.Pa fstab 264is to use the routines 265.Xr getfsent 3 , 266.Xr getfsspec 3 , 267and 268.Xr getfsfile 3 . 269.Sh FILES 270.Bl -tag -width /etc/fstab -compact 271.It Pa /etc/fstab 272.El 273.Sh EXAMPLES 274Here is a sample 275.Pa /etc/fstab 276file: 277.Bd -literal -offset indent 278/dev/sd0a / ffs rw 1 1 279/dev/sd0e /var ffs rw,nodev,nosuid 1 2 280#/dev/sd0f /tmp ffs rw,nodev,nosuid 1 2 281swap /tmp mfs rw,nodev,nosuid,-s=153600 0 0 282/dev/sd0g /usr ffs rw,nodev 1 2 283/dev/sd0h /usr/local ffs rw,nodev 1 2 284/dev/sd0i /home ffs rw,nodev,nosuid 1 2 285/dev/sd0j /usr/src ffs rw,nodev,nosuid,softdep 1 2 286/dev/sd1b none swap sw 0 0 287/dev/cd0a /cdrom cd9660 ro,noauto 0 0 288server:/export/ports /usr/ports nfs rw,nodev,nosuid,soft,intr 0 0 289.Ed 290.Sh SEE ALSO 291.Xr quota 1 , 292.Xr getfsent 3 , 293.Xr fsck 8 , 294.Xr mount 8 , 295.Xr quotacheck 8 , 296.Xr quotaon 8 297.Sh HISTORY 298The 299.Nm 300file format appeared in 301.Bx 4.0 . 302