1.\" Copyright (c) 1980, 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)fstab.5 8.1 (Berkeley) 06/05/93 7.\" 8.Dd 9.Dt FSTAB 5 10.Os BSD 4 11.Sh NAME 12.Nm fstab 13.Nd static information about the filesystems 14.Sh SYNOPSIS 15.Fd #include <fstab.h> 16.Sh DESCRIPTION 17The file 18.Nm fstab 19contains descriptive information about the various file 20systems. 21.Nm fstab 22is only read by programs, and not written; 23it is the duty of the system administrator to properly create 24and maintain this file. 25Each filesystem is described on a separate line; 26fields on each line are separated by tabs or spaces. 27The order of records in 28.Nm fstab 29is important because 30.Xr fsck 8 , 31.Xr mount 8 , 32and 33.Xr umount 8 34sequentially iterate through 35.Nm fstab 36doing their thing. 37.Pp 38The first field, 39.Pq Fa fs_spec , 40describes the block special device or 41remote filesystem to be mounted. 42For filesystems of type 43.Em ufs , 44the special file name is the block special file name, 45and not the character special file name. 46If a program needs the character special file name, 47the program must create it by appending a ``r'' after the 48last ``/'' in the special file name. 49.Pp 50The second field, 51.Pq Fa fs_file , 52describes the mount point for the filesystem. 53For swap partitions, this field should be specified as ``none''. 54.Pp 55The third field, 56.Pq Fa fs_vfstype , 57describes the type of the filesystem. 58The system currently supports four types of filesystems: 59.Bl -tag -width indent -offset indent 60.It Em ufs 61a local 62.Tn UNIX 63filesystem 64.It Em mfs 65a local memory-based 66.Tn UNIX 67filesystem 68.It Em nfs 69a Sun Microsystems compatible ``Network File System'' 70.It Em swap 71a disk partition to be used for swapping 72.El 73.Pp 74The fourth field, 75.Pq Fa fs_mntops , 76describes the mount options associated with the filesystem. 77It is formatted as a comma separated list of options. 78It contains at least the type of mount (see 79.Fa fs_type 80below) plus any additional options 81appropriate to the filesystem type. 82.Pp 83If the options ``userquota'' and/or ``groupquota'' are specified, 84the filesystem is automatically processed by the 85.Xr quotacheck 8 86command, and user and/or group disk quotas are enabled with 87.Xr quotaon 8 . 88By default, 89filesystem quotas are maintained in files named 90.Pa quota.user 91and 92.Pa quota.group 93which are located at the root of the associated filesystem. 94These defaults may be overridden by putting an equal sign 95and an alternative absolute pathname following the quota option. 96Thus, if the user quota file for 97.Pa /tmp 98is stored in 99.Pa /var/quotas/tmp.user , 100this location can be specified as: 101.Bd -literal -offset indent 102userquota=/var/quotas/tmp.user 103.Ed 104.Pp 105The type of the mount is extracted from the 106.Fa fs_mntops 107field and stored separately in the 108.Fa fs_type 109field (it is not deleted from the 110.Fa fs_mntops 111field). 112If 113.Fa fs_type 114is ``rw'' or ``ro'' then the filesystem whose name is given in the 115.Fa fs_file 116field is normally mounted read-write or read-only on the 117specified special file. 118If 119.Fa fs_type 120is ``sw'' then the special file is made available as a piece of swap 121space by the 122.Xr swapon 8 123command at the end of the system reboot procedure. 124The fields other than 125.Fa fs_spec 126and 127.Fa fs_type 128are unused. 129If 130.Fa fs_type 131is specified as ``xx'' the entry is ignored. 132This is useful to show disk partitions which are currently unused. 133.Pp 134The fifth field, 135.Pq Fa fs_freq , 136is used for these filesystems by the 137.Xr dump 8 138command to determine which filesystems need to be dumped. 139If the fifth field is not present, a value of zero is returned and 140.Xr dump 141will assume that the filesystem does not need to be dumped. 142.Pp 143The sixth field, 144.Pq Fa fs_passno , 145is used by the 146.Xr fsck 8 147program to determine the order in which filesystem checks are done 148at reboot time. 149The root filesystem should be specified with a 150.Fa fs_passno 151of 1, and other filesystems should have a 152.Fa fs_passno 153of 2. 154Filesystems within a drive will be checked sequentially, 155but filesystems on different drives will be checked at the 156same time to utilize parallelism available in the hardware. 157If the sixth field is not present or zero, 158a value of zero is returned and 159.Xr fsck 160will assume that the filesystem does not need to be checked. 161.Bd -literal 162#define FSTAB_RW "rw" /* read-write device */ 163#define FSTAB_RO "ro" /* read-only device */ 164#define FSTAB_SW "sw" /* swap device */ 165#define FSTAB_XX "xx" /* ignore totally */ 166 167struct fstab { 168 char *fs_spec; /* block special device name */ 169 char *fs_file; /* filesystem path prefix */ 170 char *fs_vfstype; /* type of filesystem */ 171 char *fs_mntops; /* comma separated mount options */ 172 char *fs_type; /* rw, ro, sw, or xx */ 173 int fs_freq; /* dump frequency, in days */ 174 int fs_passno; /* pass number on parallel dump */ 175}; 176.Ed 177.Pp 178The proper way to read records from 179.Pa fstab 180is to use the routines 181.Xr getfsent 3 , 182.Xr getfsspec 3 , 183.Xr getfstype 3 , 184and 185.Xr getfsfile 3 . 186.Sh FILES 187.Bl -tag -width /etc/fstab -compact 188.It Pa /etc/fstab 189The file 190.Nm fstab 191resides in 192.Pa /etc . 193.El 194.Sh SEE ALSO 195.Xr getfsent 3 196.Sh HISTORY 197The 198.Nm 199file format appeared in 200.Bx 4.0 . 201