1.\" $NetBSD: fstab.5,v 1.34 2007/05/19 14:43:20 wiz Exp $ 2.\" 3.\" Copyright (c) 1980, 1989, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)fstab.5 8.1 (Berkeley) 6/5/93 31.\" 32.Dd March 9, 2007 33.Dt FSTAB 5 34.Os 35.Sh NAME 36.Nm fstab 37.Nd filesystem table for devices, types, and mount points 38.Sh SYNOPSIS 39.In fstab.h 40.Sh DESCRIPTION 41The file 42.Nm 43contains descriptive information about the various file systems. 44.Nm 45is only read by programs, and not written; 46it is the duty of the system administrator to properly create 47and maintain this file. 48Each filesystem is described on a separate line; 49fields on each line are separated by tabs or spaces. Lines beginning 50with 51.Dq # 52are comments. 53The order of records in 54.Nm 55is important because 56.Xr fsck 8 , 57.Xr mount 8 , 58and 59.Xr umount 8 60sequentially iterate through 61.Nm 62doing their respective tasks. 63.Pp 64Each configuration line/record in 65.Nm 66has the format: 67.Dl fs_spec fs_file fs_vfstype fs_mntops fs_freq fs_passno 68.Pp 69The first field, 70.Pq Fa fs_spec , 71describes the block special device or 72remote filesystem to be mounted. 73For filesystems of type 74.Em ffs , 75the special file name is the block special file name, 76and not the character special file name. 77If a program needs the character special file name, 78the program must create it by appending a 79.Dq r 80after the 81last 82.Dq / 83in the special file name. 84.Pp 85The second field, 86.Pq Fa fs_file , 87describes the mount point for the filesystem. 88For swap and dump partitions, this field should be specified as 89.Dq none . 90.Pp 91The third field, 92.Pq Fa fs_vfstype , 93describes the type of the filesystem. 94The system currently supports these filesystems: 95.Bl -tag -width filecore -offset indent 96.It Em adosfs 97an 98.Tn AmigaDOS 99filesystem. 100.It Em cd9660 101an 102.Tn ISO 1039660 CD-ROM filesystem. 104.It Em ext2fs 105an implementation of the Linux 106.Dq Second Extended File-system . 107.It Em fdesc 108an implementation of 109.Pa /dev/fd . 110.It Em ffs 111a local 112.Ux 113filesystem. 114.It Em filecore 115a filesystem for 116.Tn RISC\ OS . 117.It Em kernfs 118various and sundry kernel statistics. 119.It Em lfs 120a log-structured file-system. 121.It Em mfs 122a local memory-based 123.Ux 124filesystem. 125.It Em msdos 126an 127.Tn MS-DOS 128.Dq FAT filesystem . 129.It Em nfs 130a Sun Microsystems compatible 131.Dq Network File System . 132.It Em ntfs 133a filesystem used by 134.Tn Windows NT . 135Still experimental. 136.It Em null 137a loop-back filesystem, allowing parts of the system to be viewed 138elsewhere. 139.It Em overlay 140a demonstration of layered filesystems. 141.It Em portal 142a general filesystem interface, currently supports TCP and FS mounts. 143.It Em procfs 144a local filesystem of process information. 145.It Em ptyfs 146a pseudo-terminal device file system. 147.It Em smbfs 148a shared resource from an SMB/CIFS file server. 149.It Em swap 150a disk partition to be used for swapping and paging. 151.It Em tmpfs 152an efficient memory file system. 153.It Em umap 154a user and group re-mapping filesystem. 155.It Em union 156a translucent filesystem. 157.El 158.Pp 159The fourth field, 160.Pq Fa fs_mntops , 161describes the mount options associated with the filesystem. 162It is formatted as a comma separated list of options. 163It contains at least the type of mount (see 164.Fa fs_type 165below) plus any additional options 166appropriate to the filesystem type. 167.Pp 168The option 169.Dq auto 170can be used in the 171.Dq noauto 172form to cause 173a file system not to be mounted automatically (with 174.Dq mount -a 175, 176or system boot time). 177.Pp 178If the options 179.Dq userquota 180and/or 181.Dq groupquota 182are specified, 183the filesystem is automatically processed by the 184.Xr quotacheck 8 185command, and user and/or group disk quotas are enabled with 186.Xr quotaon 8 . 187By default, 188filesystem quotas are maintained in files named 189.Pa quota.user 190and 191.Pa quota.group 192which are located at the root of the associated filesystem. 193These defaults may be overridden by putting an equal sign 194and an alternative absolute pathname following the quota option. 195Thus, if the user quota file for 196.Pa /tmp 197is stored in 198.Pa /var/quotas/tmp.user , 199this location can be specified as: 200.Bd -literal -offset indent 201userquota=/var/quotas/tmp.user 202.Ed 203.Pp 204The type of the mount is extracted from the 205.Fa fs_mntops 206field and stored separately in the 207.Fa fs_type 208field (it is not deleted from the 209.Fa fs_mntops 210field). 211If 212.Fa fs_type 213is 214.Dq rw 215or 216.Dq ro 217then the filesystem whose name is given in the 218.Fa fs_file 219field is normally mounted read-write or read-only on the 220specified special file. 221If 222.Fa fs_type 223is 224.Dq sw 225or 226.Dq dp 227then the special file is made available as a piece of swap 228or dump 229space by the 230.Xr swapctl 8 231command towards the beginning of the system reboot procedure. 232See 233.Xr swapctl 8 234for more information on configuring swap and dump devices. 235The fields other than 236.Fa fs_spec 237and 238.Fa fs_type 239are unused. 240If 241.Fa fs_type 242is specified as 243.Dq xx 244the entry is ignored. 245This is useful to show disk partitions which are currently unused. 246.Pp 247The fifth field, 248.Pq Fa fs_freq , 249is used for these filesystems by the 250.Xr dump 8 251command to determine which filesystems need to be dumped. 252If the fifth field is not present, a value of zero is returned and 253.Xr dump 8 254will assume that the filesystem does not need to be dumped. 255.Pp 256The sixth field, 257.Pq Fa fs_passno , 258is used by the 259.Xr fsck 8 260program to determine the order in which filesystem checks are done 261at reboot time. 262The root filesystem should be specified with a 263.Fa fs_passno 264of 1, and other filesystems should have a 265.Fa fs_passno 266of 2. 267Filesystems within a drive will be checked sequentially, 268but filesystems on different drives will be checked at the 269same time to use parallelism available in the hardware. 270If the sixth field is not present or zero, 271a value of zero is returned and 272.Xr fsck 8 273will assume that the filesystem does not need to be checked. 274.Bd -literal 275#define FSTAB_RW "rw" /* read-write device */ 276#define FSTAB_RQ "rq" /* read/write with quotas */ 277#define FSTAB_RO "ro" /* read-only device */ 278#define FSTAB_SW "sw" /* swap device */ 279#define FSTAB_DP "dp" /* dump device */ 280#define FSTAB_XX "xx" /* ignore totally */ 281 282struct fstab { 283 char *fs_spec; /* block special device name */ 284 char *fs_file; /* filesystem path prefix */ 285 char *fs_vfstype; /* type of filesystem */ 286 char *fs_mntops; /* comma separated mount options */ 287 char *fs_type; /* rw, ro, sw, or xx */ 288 int fs_freq; /* dump frequency, in days */ 289 int fs_passno; /* pass number on parallel fsck */ 290}; 291.Ed 292.Pp 293The proper way to read records from 294.Pa fstab 295is to use the routines 296.Xr getfsent 3 , 297.Xr getfsspec 3 , 298and 299.Xr getfsfile 3 . 300.Sh FILES 301.Bl -tag -width /etc/fstab 302.It Pa /etc/fstab 303The location of 304.Nm 305configuration file. 306.It Pa /usr/share/examples/fstab/ 307Some useful configuration examples. 308.El 309.Sh SEE ALSO 310.Xr getfsent 3 , 311.Xr mount 8 , 312.Xr swapctl 8 313.Sh HISTORY 314The 315.Nm 316file format appeared in 317.Bx 4.0 . 318