.\" $NetBSD: fstab.5,v 1.44.2.1 2020/02/12 19:44:27 martin Exp $ .\" .\" Copyright (c) 1980, 1989, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)fstab.5 8.1 (Berkeley) 6/5/93 .\" .Dd September 15, 2019 .Dt FSTAB 5 .Os .Sh NAME .Nm fstab .Nd file system table for devices, types, and mount points .Sh SYNOPSIS .In fstab.h .Sh DESCRIPTION The file .Nm contains descriptive information about the various file systems. .Nm is only read by programs, and not written; it is the duty of the system administrator to properly create and maintain this file. Each file system is described on a separate line; fields on each line are separated by tabs or spaces. Lines beginning with .Dq # are comments. The order of records in .Nm is important because .Xr fsck 8 , .Xr mount 8 , and .Xr umount 8 sequentially iterate through .Nm doing their respective tasks. .Pp Each configuration line/record in .Nm has the format: .Dl fs_spec fs_file fs_vfstype fs_mntops fs_freq fs_passno .Pp The first field, .Pq Fa fs_spec , describes the block special device or remote file system to be mounted. For file systems of type .Em ffs , the special file name is the block special file name, and not the character special file name. If a program needs the character special file name, the program must create it by appending a .Dq r after the last .Dq / in the special file name. .Pp If the first field is of the form .Dq NAME= then all the .Xr dk 4 wedge partitions are searched for one that has a wedge name equal to .Ar and the device corresponding to it is selected. .Pp If the first field starts with the prefix .Dq ROOT. the prefix is replaced with .Dq /dev/[root_device] , where .Bq root_device is the value of the .Dq kern.root_device sysctl. .Pp The second field, .Pq Fa fs_file , describes the mount point for the file system. For swap and dump partitions, this field should be specified as .Dq none . .Pp The third field, .Pq Fa fs_vfstype , describes the type of the file system. The system currently supports these file systems: .Bl -tag -width filecore -offset indent .It Em adosfs an .Tn AmigaDOS file system. .It Em cd9660 an .Tn ISO 9660 CD-ROM file system. .It Em ext2fs an implementation of the Linux .Dq Second Extended File-system . .It Em fdesc an implementation of .Pa /dev/fd . .It Em ffs a local .Ux file system. .It Em filecore a file system for .Tn RISC\ OS . .It Em kernfs various and sundry kernel statistics. .It Em lfs a log-structured file-system. .It Em mfs a local memory-based .Ux file system. .It Em msdos an .Tn MS-DOS .Dq FAT file system . .It Em nfs a Sun Microsystems compatible .Dq Network File System . .It Em ntfs a file system used by .Tn Windows NT . Still experimental. .It Em null a loop-back file system, allowing parts of the system to be viewed elsewhere. .It Em overlay a demonstration of layered file systems. .It Em portal a general file system interface, currently supports TCP and FS mounts. .It Em procfs a local file system of process information. .It Em ptyfs a pseudo-terminal device file system. .It Em smbfs a shared resource from an SMB/CIFS file server. .It Em swap a disk partition to be used for swapping and paging. .It Em tmpfs an efficient memory file system. .It Em umap a user and group re-mapping file system. .It Em union a translucent file system. .It Em zfs a ZFS file system. .El .Pp The fourth field, .Pq Fa fs_mntops , describes the mount options associated with the file system. It is formatted as a comma separated list of options. It contains at least the type of mount (see .Fa fs_type below) plus any additional options appropriate to the file system type. .Pp The option .Dq auto can be used in the .Dq noauto form to cause a file system not to be mounted automatically (with .Dq mount -a , or system boot time). .Pp If the options .Dq userquota and/or .Dq groupquota are specified, the file system is automatically processed by the .Xr quotacheck 8 command, and legacy user and/or group disk quotas are enabled with .Xr quotaon 8 . By default, file system quotas are maintained in files named .Pa quota.user and .Pa quota.group which are located at the root of the associated file system. These defaults may be overridden by putting an equal sign and an alternative absolute pathname following the quota option. Thus, if the user quota file for .Pa /tmp is stored in .Pa /var/quotas/tmp.user , this location can be specified as: .Bd -literal -offset indent userquota=/var/quotas/tmp.user .Ed .Pp It is recommended to turn on the new, in-file system quota with .Xr tunefs 8 or at .Xr newfs 8 time, and to not use the .Dq userquota or .Dq groupquota options. Migration of limits to the new in-file system quota can be handled via .Xr quotadump 8 and .Xr quotarestore 8 . .Pp The option .Dq rump is used to mount the file system using a .Xr rump 3 userspace server instead of the kernel server. .Pp The type of the mount is extracted from the .Fa fs_mntops field and stored separately in the .Fa fs_type field (it is not deleted from the .Fa fs_mntops field). If .Fa fs_type is .Dq rw or .Dq ro then the file system whose name is given in the .Fa fs_file field is normally mounted read-write or read-only on the specified special file. If .Fa fs_type is .Dq sw or .Dq dp then the special file is made available as a piece of swap or dump space by the .Xr swapctl 8 command towards the beginning of the system reboot procedure. See .Xr swapctl 8 for more information on configuring swap and dump devices. The fields other than .Fa fs_spec and .Fa fs_type are unused. If .Fa fs_type is specified as .Dq xx the entry is ignored. This is useful to show disk partitions which are currently unused. .Pp The fifth field, .Pq Fa fs_freq , is used for these file systems by the .Xr dump 8 command to determine which file systems need to be dumped. If the fifth field is not present, a value of zero is returned and .Xr dump 8 will assume that the file system does not need to be dumped. .Pp The sixth field, .Pq Fa fs_passno , is used by the .Xr fsck 8 program to determine the order in which file system checks are done at reboot time. The root file system should be specified with a .Fa fs_passno of 1, and other file systems should have a .Fa fs_passno of 2. Filesystems within a drive will be checked sequentially, but file systems on different drives will be checked at the same time to use parallelism available in the hardware. If the sixth field is not present or zero, a value of zero is returned and .Xr fsck 8 will assume that the file system does not need to be checked. .Bd -literal #define FSTAB_RW "rw" /* read-write device */ #define FSTAB_RQ "rq" /* read/write with quotas */ #define FSTAB_RO "ro" /* read-only device */ #define FSTAB_SW "sw" /* swap device */ #define FSTAB_DP "dp" /* dump device */ #define FSTAB_XX "xx" /* ignore totally */ struct fstab { char *fs_spec; /* block special device name */ char *fs_file; /* file system path prefix */ char *fs_vfstype; /* type of file system */ char *fs_mntops; /* comma separated mount options */ char *fs_type; /* rw, ro, sw, or xx */ int fs_freq; /* dump frequency, in days */ int fs_passno; /* pass number on parallel fsck */ }; .Ed .Pp The proper way to read records from .Pa fstab is to use the routines .Xr getfsent 3 , .Xr getfsspec 3 , and .Xr getfsfile 3 . .Sh FILES .Bl -tag -width /etc/fstab .It Pa /etc/fstab The location of .Nm configuration file. .It Pa /usr/share/examples/fstab/ Some useful configuration examples. .El .Sh EXAMPLES To use .Dq NAME on a non-GPT disk, use: .Bd -literal NAME=sb2k5Root/a / ffs rw,log 1 1 NAME=sb2k5Root/b none swap sw,dp 0 0 .Ed .Pp For a .Xr gpt 8 disk, use: .Bd -literal NAME=firstpartition / ffs rw,log 1 1 NAME=secondpartition none swap sw,dp 0 0 .Ed .Sh SEE ALSO .Xr getfsent 3 , .Xr getfsspecname 3 , .Xr mount 8 , .Xr swapctl 8 .Sh HISTORY The .Nm file format appeared in .Bx 4.0 .