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Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)fstab.5 8.1 (Berkeley) 6/5/93 29.\" $FreeBSD: src/share/man/man5/fstab.5,v 1.11.2.8 2003/02/10 12:21:08 des Exp $ 30.\" 31.Dd March 20, 2020 32.Dt FSTAB 5 33.Os 34.Sh NAME 35.Nm fstab 36.Nd static information about the file systems 37.Sh SYNOPSIS 38.In fstab.h 39.Sh DESCRIPTION 40The file 41.Nm 42contains descriptive information about the various file 43systems. 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. 50The order of records in 51.Nm 52is important because 53.Xr fsck 8 , 54.Xr mount 8 , 55and 56.Xr umount 8 57sequentially iterate through 58.Nm 59doing their thing. 60.Pp 61The first field, 62.Pq Fa fs_spec , 63describes the special file or 64remote file system to be mounted. 65This may be a 66.Pa /dev/<path> , 67a label from a 68.Xr devtab 5 69(typically 70.Pa /etc/devtab ) , 71or a 72.Pa <host>:<path> 73for NFS. 74Note that 75.Xr devtab 5 76labels maybe augmented with a 77.Pa .suffix 78trailer. 79For example 80.Pa mydisk.s1a . 81Also note 82.Pa /dev 83based paths can mount serial numbers similar to 84.Xr devtab 5 85labels by using the path 86.Pa /dev/serno/SERIALNO[.suffix] . 87.Pp 88The second field, 89.Pq Fa fs_file , 90describes the mount point for the file system. 91For swap partitions, this field should be specified as 92.Dq none . 93.Pp 94The third field, 95.Pq Fa fs_vfstype , 96describes the type of the file system. 97The system can support various file system types. 98Only the root, 99.Pa /usr , 100and 101.Pa /tmp 102file systems need be statically 103compiled into the kernel; 104everything else will be automatically loaded at mount 105time. 106(Exception: the UFS family - FFS, MFS, and LFS cannot 107currently be demand-loaded.) Some people still prefer to statically 108compile other file systems as well. 109.Pp 110The most common file system types are: 111.Bl -tag -width ".Em HAMMER2" -offset indent 112.It Em HAMMER 113a local 114.Xr HAMMER 5 115file system 116.It Em HAMMER2 117a local HAMMER2 file system 118.It Em ufs 119a local 120.Xr ffs 5 121.Ux 122file system 123.It Em mfs 124a local memory-based 125.Ux 126file system 127.It Em nfs 128a Sun Microsystems compatible 129.Dq "Network File System" 130.It Em swap 131a disk partition to be used for swapping 132.It Em msdos 133a local 134.Xr msdos 5 135DOS compatible file system 136.It Em cd9660 137a local CD-ROM file system (as per ISO 9660) 138.\" maybe also say Rock Ridge extensions are handled ? 139.It Em procfs 140a file system for accessing process data 141.El 142.Pp 143The fourth field, 144.Pq Fa fs_mntops , 145describes the mount options associated with the file system. 146It is formatted as a comma separated list of options. 147It contains at least the type of mount (see 148.Fa fs_type 149below) plus any additional options 150appropriate to the file system type. 151See the options flag 152.Pq Fl o 153in the 154.Xr mount 8 155page and the file system specific page, such as 156.Xr mount_nfs 8 , 157for additional options that may be specified. 158.Pp 159If the options ``userquota'' and/or ``groupquota'' are specified, 160the file system is automatically processed by the 161.Xr quotacheck 8 162command, and user and/or group disk quotas are enabled with 163.Xr quotaon 8 . 164By default, 165file system quotas are maintained in files named 166.Pa quota.user 167and 168.Pa quota.group 169which are located at the root of the associated file system. 170These defaults may be overridden by putting an equal sign 171and an alternative absolute pathname following the quota option. 172Thus, if the user quota file for 173.Pa /tmp 174is stored in 175.Pa /var/quotas/tmp.user , 176this location can be specified as: 177.Bd -literal -offset indent 178userquota=/var/quotas/tmp.user 179.Ed 180.Pp 181If the option ``noauto'' is specified, the file system will not be automatically 182mounted at system startup. 183This is recommended for all remote file systems other than NFS, 184since only NFS mounts are delayed until after network initialization 185by the 186.Xr rc 8 187startup scripts. 188.Pp 189Swap partitions may specify the option ``crypt'' to automatically encrypt 190the swap partition with a random key. 191Note that you will not be able to 192recover any kernel core dumps if you use this option. 193.Pp 194The type of the mount is extracted from the 195.Fa fs_mntops 196field and stored separately in the 197.Fa fs_type 198field (it is not deleted from the 199.Fa fs_mntops 200field). 201If 202.Fa fs_type 203is ``rw'' or ``ro'' then the file system whose name is given in the 204.Fa fs_file 205field is normally mounted read-write or read-only on the 206specified special file. 207If 208.Fa fs_type 209is ``sw'' then the special file is made available as a piece of swap 210space by the 211.Xr swapon 8 212command at the end of the system reboot procedure. 213The fields other than 214.Fa fs_spec 215and 216.Fa fs_type 217are unused. 218If 219.Fa fs_type 220is specified as ``xx'' the entry is ignored. 221This is useful to show disk partitions which are currently unused. 222.Pp 223The fifth field, 224.Pq Fa fs_freq , 225is used for these file systems by the 226.Xr dump 8 227command to determine which file systems need to be dumped. 228If the fifth field is not present, a value of zero is returned and 229.Nm dump 230will assume that the file system does not need to be dumped. 231.Pp 232The sixth field, 233.Pq Fa fs_passno , 234is used by the 235.Xr fsck 8 236program to determine the order in which file system checks are done 237at reboot time. 238The root file system should be specified with a 239.Fa fs_passno 240of 1, and other file systems should have a 241.Fa fs_passno 242of 2. 243File systems within a drive will be checked sequentially, 244but file systems on different drives will be checked at the 245same time to utilize parallelism available in the hardware. 246If the sixth field is not present or is zero, 247a value of zero is returned and 248.Xr fsck 8 249will assume that the file system does not need to be checked. 250.Bd -literal 251#define FSTAB_RW "rw" /* read/write device */ 252#define FSTAB_RQ "rq" /* read/write with quotas */ 253#define FSTAB_RO "ro" /* read-only device */ 254#define FSTAB_SW "sw" /* swap device */ 255#define FSTAB_XX "xx" /* ignore totally */ 256 257struct fstab { 258 char *fs_spec; /* block special device name */ 259 char *fs_file; /* file system path prefix */ 260 char *fs_vfstype; /* File system type, ufs, nfs */ 261 char *fs_mntops; /* Mount options ala -o */ 262 char *fs_type; /* FSTAB_* from fs_mntops */ 263 int fs_freq; /* dump frequency, in days */ 264 int fs_passno; /* pass number on parallel fsck */ 265}; 266.Ed 267.Pp 268The proper way to read records from 269.Nm 270is to use the routines 271.Xr getfsent 3 , 272.Xr getfsspec 3 , 273.Xr getfstype 3 , 274and 275.Xr getfsfile 3 . 276.Sh FILES 277.Bl -tag -width /etc/fstab -compact 278.It Pa /etc/fstab 279The file 280.Nm 281resides in 282.Pa /etc . 283.El 284.Sh SEE ALSO 285.Xr getfsent 3 , 286.Xr getvfsbyname 3 , 287.Xr HAMMER 5 , 288.\".Xr HAMMER2 5 , 289.Xr dump 8 , 290.Xr fsck 8 , 291.Xr mount 8 , 292.Xr quotacheck 8 , 293.Xr quotaon 8 , 294.Xr swapon 8 , 295.Xr umount 8 296.Sh HISTORY 297The 298.Nm 299file format appeared in 300.Bx 4.0 . 301