1.\" $NetBSD: fstab.5,v 1.45 2019/09/15 21:04:40 gutteridge 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 September 15, 2019 33.Dt FSTAB 5 34.Os 35.Sh NAME 36.Nm fstab 37.Nd file system 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 file system 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 file system to be mounted. 74For file systems 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 86If the first field is of the form 87.Dq NAME=<value> 88then all the 89.Xr dk 4 90wedge partitions are searched for one that has a wedge name equal to 91.Ar <value> 92and the device corresponding to it is selected. 93.Pp 94If the first field starts with the prefix 95.Dq ROOT. 96the prefix is replaced with 97.Dq /dev/[root_device] , 98where 99.Bq root_device 100is the value of the 101.Dq kern.root_device 102sysctl. 103.Pp 104The second field, 105.Pq Fa fs_file , 106describes the mount point for the file system. 107For swap and dump partitions, this field should be specified as 108.Dq none . 109.Pp 110The third field, 111.Pq Fa fs_vfstype , 112describes the type of the file system. 113The system currently supports these file systems: 114.Bl -tag -width filecore -offset indent 115.It Em adosfs 116an 117.Tn AmigaDOS 118file system. 119.It Em cd9660 120an 121.Tn ISO 1229660 CD-ROM file system. 123.It Em ext2fs 124an implementation of the Linux 125.Dq Second Extended File-system . 126.It Em fdesc 127an implementation of 128.Pa /dev/fd . 129.It Em ffs 130a local 131.Ux 132file system. 133.It Em filecore 134a file system for 135.Tn RISC\ OS . 136.It Em kernfs 137various and sundry kernel statistics. 138.It Em lfs 139a log-structured file-system. 140.It Em mfs 141a local memory-based 142.Ux 143file system. 144.It Em msdos 145an 146.Tn MS-DOS 147.Dq FAT file system . 148.It Em nfs 149a Sun Microsystems compatible 150.Dq Network File System . 151.It Em ntfs 152a file system used by 153.Tn Windows NT . 154Still experimental. 155.It Em null 156a loop-back file system, allowing parts of the system to be viewed 157elsewhere. 158.It Em overlay 159a demonstration of layered file systems. 160.It Em portal 161a general file system interface, currently supports TCP and FS mounts. 162.It Em procfs 163a local file system of process information. 164.It Em ptyfs 165a pseudo-terminal device file system. 166.It Em smbfs 167a shared resource from an SMB/CIFS file server. 168.It Em swap 169a disk partition to be used for swapping and paging. 170.It Em tmpfs 171an efficient memory file system. 172.It Em umap 173a user and group re-mapping file system. 174.It Em union 175a translucent file system. 176.It Em zfs 177a ZFS file system. 178.El 179.Pp 180The fourth field, 181.Pq Fa fs_mntops , 182describes the mount options associated with the file system. 183It is formatted as a comma separated list of options. 184It contains at least the type of mount (see 185.Fa fs_type 186below) plus any additional options 187appropriate to the file system type. 188.Pp 189The option 190.Dq auto 191can be used in the 192.Dq noauto 193form to cause 194a file system not to be mounted automatically (with 195.Dq mount -a 196, 197or system boot time). 198.Pp 199If the options 200.Dq userquota 201and/or 202.Dq groupquota 203are specified, 204the file system is automatically processed by the 205.Xr quotacheck 8 206command, and legacy user and/or group disk quotas are enabled with 207.Xr quotaon 8 . 208By default, 209file system quotas are maintained in files named 210.Pa quota.user 211and 212.Pa quota.group 213which are located at the root of the associated file system. 214These defaults may be overridden by putting an equal sign 215and an alternative absolute pathname following the quota option. 216Thus, if the user quota file for 217.Pa /tmp 218is stored in 219.Pa /var/quotas/tmp.user , 220this location can be specified as: 221.Bd -literal -offset indent 222userquota=/var/quotas/tmp.user 223.Ed 224.Pp 225It is recommended to turn on the new, in-file system quota with 226.Xr tunefs 8 227or at 228.Xr newfs 8 229time, and to not use the 230.Dq userquota 231or 232.Dq groupquota 233options. 234Migration of limits to the new in-file system quota can be handled 235via 236.Xr quotadump 8 237and 238.Xr quotarestore 8 . 239.Pp 240The option 241.Dq rump 242is used to mount the file system using a 243.Xr rump 3 244userspace server instead of the kernel server. 245.Pp 246The type of the mount is extracted from the 247.Fa fs_mntops 248field and stored separately in the 249.Fa fs_type 250field (it is not deleted from the 251.Fa fs_mntops 252field). 253If 254.Fa fs_type 255is 256.Dq rw 257or 258.Dq ro 259then the file system whose name is given in the 260.Fa fs_file 261field is normally mounted read-write or read-only on the 262specified special file. 263If 264.Fa fs_type 265is 266.Dq sw 267or 268.Dq dp 269then the special file is made available as a piece of swap 270or dump 271space by the 272.Xr swapctl 8 273command towards the beginning of the system reboot procedure. 274See 275.Xr swapctl 8 276for more information on configuring swap and dump devices. 277The fields other than 278.Fa fs_spec 279and 280.Fa fs_type 281are unused. 282If 283.Fa fs_type 284is specified as 285.Dq xx 286the entry is ignored. 287This is useful to show disk partitions which are currently unused. 288.Pp 289The fifth field, 290.Pq Fa fs_freq , 291is used for these file systems by the 292.Xr dump 8 293command to determine which file systems need to be dumped. 294If the fifth field is not present, a value of zero is returned and 295.Xr dump 8 296will assume that the file system does not need to be dumped. 297.Pp 298The sixth field, 299.Pq Fa fs_passno , 300is used by the 301.Xr fsck 8 302program to determine the order in which file system checks are done 303at reboot time. 304The root file system should be specified with a 305.Fa fs_passno 306of 1, and other file systems should have a 307.Fa fs_passno 308of 2. 309Filesystems within a drive will be checked sequentially, 310but file systems on different drives will be checked at the 311same time to use parallelism available in the hardware. 312If the sixth field is not present or zero, 313a value of zero is returned and 314.Xr fsck 8 315will assume that the file system does not need to be checked. 316.Bd -literal 317#define FSTAB_RW "rw" /* read-write device */ 318#define FSTAB_RQ "rq" /* read/write with quotas */ 319#define FSTAB_RO "ro" /* read-only device */ 320#define FSTAB_SW "sw" /* swap device */ 321#define FSTAB_DP "dp" /* dump device */ 322#define FSTAB_XX "xx" /* ignore totally */ 323 324struct fstab { 325 char *fs_spec; /* block special device name */ 326 char *fs_file; /* file system path prefix */ 327 char *fs_vfstype; /* type of file system */ 328 char *fs_mntops; /* comma separated mount options */ 329 char *fs_type; /* rw, ro, sw, or xx */ 330 int fs_freq; /* dump frequency, in days */ 331 int fs_passno; /* pass number on parallel fsck */ 332}; 333.Ed 334.Pp 335The proper way to read records from 336.Pa fstab 337is to use the routines 338.Xr getfsent 3 , 339.Xr getfsspec 3 , 340and 341.Xr getfsfile 3 . 342.Sh FILES 343.Bl -tag -width /etc/fstab 344.It Pa /etc/fstab 345The location of 346.Nm 347configuration file. 348.It Pa /usr/share/examples/fstab/ 349Some useful configuration examples. 350.El 351.Sh EXAMPLES 352To use 353.Dq NAME 354on a non-GPT disk, use: 355.Bd -literal 356NAME=sb2k5Root/a / ffs rw,log 1 1 357NAME=sb2k5Root/b none swap sw,dp 0 0 358.Ed 359.Pp 360For a 361.Xr gpt 8 362disk, use: 363.Bd -literal 364NAME=firstpartition / ffs rw,log 1 1 365NAME=secondpartition none swap sw,dp 0 0 366.Ed 367.Sh SEE ALSO 368.Xr getfsent 3 , 369.Xr getfsspecname 3 , 370.Xr mount 8 , 371.Xr swapctl 8 372.Sh HISTORY 373The 374.Nm 375file format appeared in 376.Bx 4.0 . 377