1.\" $NetBSD: fstab.5,v 1.36 2009/01/11 22:03:56 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 January 11, 2009 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. 50Lines beginning 51with 52.Dq # 53are comments. 54The order of records in 55.Nm 56is important because 57.Xr fsck 8 , 58.Xr mount 8 , 59and 60.Xr umount 8 61sequentially iterate through 62.Nm 63doing their respective tasks. 64.Pp 65Each configuration line/record in 66.Nm 67has the format: 68.Dl fs_spec fs_file fs_vfstype fs_mntops fs_freq fs_passno 69.Pp 70The first field, 71.Pq Fa fs_spec , 72describes the block special device or 73remote filesystem to be mounted. 74For filesystems of type 75.Em ffs , 76the special file name is the block special file name, 77and not the character special file name. 78If a program needs the character special file name, 79the program must create it by appending a 80.Dq r 81after the 82last 83.Dq / 84in the special file name. 85.Pp 86The second field, 87.Pq Fa fs_file , 88describes the mount point for the filesystem. 89For swap and dump partitions, this field should be specified as 90.Dq none . 91.Pp 92The third field, 93.Pq Fa fs_vfstype , 94describes the type of the filesystem. 95The system currently supports these filesystems: 96.Bl -tag -width filecore -offset indent 97.It Em adosfs 98an 99.Tn AmigaDOS 100filesystem. 101.It Em cd9660 102an 103.Tn ISO 1049660 CD-ROM filesystem. 105.It Em ext2fs 106an implementation of the Linux 107.Dq Second Extended File-system . 108.It Em fdesc 109an implementation of 110.Pa /dev/fd . 111.It Em ffs 112a local 113.Ux 114filesystem. 115.It Em filecore 116a filesystem for 117.Tn RISC\ OS . 118.It Em kernfs 119various and sundry kernel statistics. 120.It Em lfs 121a log-structured file-system. 122.It Em mfs 123a local memory-based 124.Ux 125filesystem. 126.It Em msdos 127an 128.Tn MS-DOS 129.Dq FAT filesystem . 130.It Em nfs 131a Sun Microsystems compatible 132.Dq Network File System . 133.It Em ntfs 134a filesystem used by 135.Tn Windows NT . 136Still experimental. 137.It Em null 138a loop-back filesystem, allowing parts of the system to be viewed 139elsewhere. 140.It Em overlay 141a demonstration of layered filesystems. 142.It Em portal 143a general filesystem interface, currently supports TCP and FS mounts. 144.It Em procfs 145a local filesystem of process information. 146.It Em ptyfs 147a pseudo-terminal device file system. 148.It Em smbfs 149a shared resource from an SMB/CIFS file server. 150.It Em swap 151a disk partition to be used for swapping and paging. 152.It Em tmpfs 153an efficient memory file system. 154.It Em umap 155a user and group re-mapping filesystem. 156.It Em union 157a translucent filesystem. 158.El 159.Pp 160The fourth field, 161.Pq Fa fs_mntops , 162describes the mount options associated with the filesystem. 163It is formatted as a comma separated list of options. 164It contains at least the type of mount (see 165.Fa fs_type 166below) plus any additional options 167appropriate to the filesystem type. 168.Pp 169The option 170.Dq auto 171can be used in the 172.Dq noauto 173form to cause 174a file system not to be mounted automatically (with 175.Dq mount -a 176, 177or system boot time). 178.Pp 179If the options 180.Dq userquota 181and/or 182.Dq groupquota 183are specified, 184the filesystem is automatically processed by the 185.Xr quotacheck 8 186command, and user and/or group disk quotas are enabled with 187.Xr quotaon 8 . 188By default, 189filesystem quotas are maintained in files named 190.Pa quota.user 191and 192.Pa quota.group 193which are located at the root of the associated filesystem. 194These defaults may be overridden by putting an equal sign 195and an alternative absolute pathname following the quota option. 196Thus, if the user quota file for 197.Pa /tmp 198is stored in 199.Pa /var/quotas/tmp.user , 200this location can be specified as: 201.Bd -literal -offset indent 202userquota=/var/quotas/tmp.user 203.Ed 204.Pp 205The option 206.Dq rump 207is used to mount the file system using a 208.Xr rump 3 209userspace server instead of the kernel server. 210.Pp 211The type of the mount is extracted from the 212.Fa fs_mntops 213field and stored separately in the 214.Fa fs_type 215field (it is not deleted from the 216.Fa fs_mntops 217field). 218If 219.Fa fs_type 220is 221.Dq rw 222or 223.Dq ro 224then the filesystem whose name is given in the 225.Fa fs_file 226field is normally mounted read-write or read-only on the 227specified special file. 228If 229.Fa fs_type 230is 231.Dq sw 232or 233.Dq dp 234then the special file is made available as a piece of swap 235or dump 236space by the 237.Xr swapctl 8 238command towards the beginning of the system reboot procedure. 239See 240.Xr swapctl 8 241for more information on configuring swap and dump devices. 242The fields other than 243.Fa fs_spec 244and 245.Fa fs_type 246are unused. 247If 248.Fa fs_type 249is specified as 250.Dq xx 251the entry is ignored. 252This is useful to show disk partitions which are currently unused. 253.Pp 254The fifth field, 255.Pq Fa fs_freq , 256is used for these filesystems by the 257.Xr dump 8 258command to determine which filesystems need to be dumped. 259If the fifth field is not present, a value of zero is returned and 260.Xr dump 8 261will assume that the filesystem does not need to be dumped. 262.Pp 263The sixth field, 264.Pq Fa fs_passno , 265is used by the 266.Xr fsck 8 267program to determine the order in which filesystem checks are done 268at reboot time. 269The root filesystem should be specified with a 270.Fa fs_passno 271of 1, and other filesystems should have a 272.Fa fs_passno 273of 2. 274Filesystems within a drive will be checked sequentially, 275but filesystems on different drives will be checked at the 276same time to use parallelism available in the hardware. 277If the sixth field is not present or zero, 278a value of zero is returned and 279.Xr fsck 8 280will assume that the filesystem does not need to be checked. 281.Bd -literal 282#define FSTAB_RW "rw" /* read-write device */ 283#define FSTAB_RQ "rq" /* read/write with quotas */ 284#define FSTAB_RO "ro" /* read-only device */ 285#define FSTAB_SW "sw" /* swap device */ 286#define FSTAB_DP "dp" /* dump device */ 287#define FSTAB_XX "xx" /* ignore totally */ 288 289struct fstab { 290 char *fs_spec; /* block special device name */ 291 char *fs_file; /* filesystem path prefix */ 292 char *fs_vfstype; /* type of filesystem */ 293 char *fs_mntops; /* comma separated mount options */ 294 char *fs_type; /* rw, ro, sw, or xx */ 295 int fs_freq; /* dump frequency, in days */ 296 int fs_passno; /* pass number on parallel fsck */ 297}; 298.Ed 299.Pp 300The proper way to read records from 301.Pa fstab 302is to use the routines 303.Xr getfsent 3 , 304.Xr getfsspec 3 , 305and 306.Xr getfsfile 3 . 307.Sh FILES 308.Bl -tag -width /etc/fstab 309.It Pa /etc/fstab 310The location of 311.Nm 312configuration file. 313.It Pa /usr/share/examples/fstab/ 314Some useful configuration examples. 315.El 316.Sh SEE ALSO 317.Xr getfsent 3 , 318.Xr mount 8 , 319.Xr swapctl 8 320.Sh HISTORY 321The 322.Nm 323file format appeared in 324.Bx 4.0 . 325