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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 April 14, 2014 .Dt FSTAB 5 .Os .Sh NAME .Nm fstab .Nd static information about the file systems .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. 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 thing. .Pp The first field, .Pq Fa fs_spec , describes the special device or remote file system to be mounted. The contents are decoded by the .Xr strunvis 3 function. This allows using spaces or tabs in the device name which would be interpreted as field separators otherwise. .Pp The second field, .Pq Fa fs_file , describes the mount point for the file system. For swap partitions, this field should be specified as .Dq none . The contents are decoded by the .Xr strunvis 3 function, as above. .Pp The third field, .Pq Fa fs_vfstype , describes the type of the file system. The system can support various file system types. Only the root, /usr, and /tmp file systems need be statically compiled into the kernel; everything else will be automatically loaded at mount time. (Exception: the FFS cannot currently be demand-loaded.) Some people still prefer to statically compile other file systems as well. .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. See the options flag .Pq Fl o in the .Xr mount 8 page and the file system specific page, such as .Xr mount_nfs 8 , for additional options that may be specified. All options that can be given to the file system specific mount commands can be used in .Nm as well. They just need to be formatted a bit differently. The arguments of the .Fl o option can be used without the preceding .Fl o flag. Other options need both the file system specific flag and its argument, separated by an equal sign. For example, mounting an .Xr msdosfs 5 filesystem, the options .Bd -literal -offset indent -o sync -o noatime -m 644 -M 755 -u foo -g bar .Ed .Pp should be written as .Bd -literal -offset indent sync,noatime,-m=644,-M=755,-u=foo,-g=bar .Ed .Pp in the option field of .Nm . .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 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 If the option .Dq failok is specified, the system will ignore any error which happens during the mount of that filesystem, which would otherwise cause the system to drop into single user mode. This option is implemented by the .Xr mount 8 command and will not be passed to the kernel. .Pp If the option .Dq noauto is specified, the file system will not be automatically mounted at system startup. Note that, for network file systems of third party types (i.e., types supported by additional software not included in the base system) to be automatically mounted at system startup, the .Va extra_netfs_types .Xr rc.conf 5 variable must be used to extend the .Xr rc 8 startup script's list of network file system types. .Pp If the option .Dq late is specified, the file system will be automatically mounted at a stage of system startup after remote mount points are mounted. For more detail about this option, see the .Xr mount 8 manual page. .Pp If the option .Dq update is specified, it indicates that the status of an already mounted file system should be changed accordingly. This allows, for example, file systems mounted read-only to be upgraded read-write and vice-versa. By default, an entry corresponding to a file systems that is already mounted is going to be skipped over when processing .Nm , unless it's a root file system, in which case logic similar to .Dq update is applied automatically. .Pp The .Dq update option is typically used in conjunction with two .Nm files. The first .Nm file is used to set up the initial set of file systems. The second .Nm file is then run to update the initial set of file systems and to add additional file systems. .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. .Pp If .Fa fs_type is .Dq sw then the special file is made available as a piece of swap space by the .Xr swapon 8 command at the end of the system reboot procedure. For swap devices, the keyword .Dq trimonce triggers the delivery of a .Dv BIO_DELETE command to the device. This command marks the device's blocks as unused, except those that might store a disk label. This marking can erase a crash dump. To delay .Nm swapon for a device until after .Nm savecore has copied the crash dump to another location, use the .Dq late option. For vnode-backed swap spaces, .Dq file is supported in the .Fa fs_mntops field. When .Fa fs_spec is an .Xr md 4 device file .Pq Do md Dc or Do md[0-9]* Dc and .Dq file is specified in .Fa fs_mntopts , an .Xr md 4 device is created with the specified file used as backing store, and then the new device is used as swap space. Swap entries on .Pa .eli devices will cause automatic creation of encrypted devices. The .Dq ealgo , .Dq aalgo , .Dq keylen , .Dq notrim , and .Dq sectorsize options may be passed to control those .Xr geli 8 parameters. 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 .Nm dump will assume that the file system does not need to be dumped. If the fifth field is greater than 0, then it specifies the number of days between dumps for this file system. .Pp The sixth field, .Pq Fa fs_passno , is used by the .Xr fsck 8 and .Xr quotacheck 8 programs to determine the order in which file system and quota checks are done at reboot time. The .Fa fs_passno field can be any value between 0 and .Ql INT_MAX Ns -1 . .Pp 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 or greater. A file system with a .Fa fs_passno value of 1 is always checked sequentially and be completed before another file system is processed, and it will be processed before all file systems with a larger .Fa fs_passno . .Pp For any given value of .Fa fs_passno , file systems within a drive will be checked sequentially, but file systems on different drives will be checked at the same time to utilize parallelism available in the hardware. Once all file system checks are complete for the current .Fa fs_passno , the same process will start over for the next .Fa fs_passno . .Pp If the sixth field is not present or is zero, a value of zero is returned and .Xr fsck 8 and .Xr quotacheck 8 will assume that the file system does not need to be checked. .Pp The .Fa fs_passno field can be used to implement finer control when the system utilities may determine that the file system resides on a different physical device, when it actually does not, as with a .Xr ccd 4 device. All file systems with a lower .Fa fs_passno value will be completed before starting on file systems with a higher .Fa fs_passno value. E.g. all file systems with a .Fa fs_passno of 2 will be completed before any file systems with a .Fa fs_passno of 3 or greater are started. Gaps are allowed between the different .Fa fs_passno values. E.g. file systems listed in .Pa /etc/fstab may have .Fa fs_passno values such as 0, 1, 2, 15, 100, 200, 300, and may appear in any order within .Pa /etc/fstab . .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_XX "xx" /* ignore totally */ struct fstab { char *fs_spec; /* block special device name */ char *fs_file; /* file system path prefix */ char *fs_vfstype; /* File system type, ufs, nfs */ char *fs_mntops; /* Mount options ala -o */ char *fs_type; /* FSTAB_* from fs_mntops */ 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 , .Xr getfstype 3 , and .Xr getfsfile 3 . .Sh FILES .Bl -tag -width /etc/fstab -compact .It Pa /etc/fstab The file .Nm resides in .Pa /etc . .El .Sh EXAMPLES .Bd -literal # Device Mountpoint FStype Options Dump Pass# # # UFS file system. /dev/da0p2 / ufs rw 1 1 # # Swap space on a block device. /dev/da0p1 none swap sw 0 0 # # Swap space using a block device with GBDE/GELI encryption. # aalgo, ealgo, keylen, sectorsize options are available # for .eli devices. /dev/da1p1.bde none swap sw 0 0 /dev/da1p2.eli none swap sw 0 0 # # tmpfs. tmpfs /tmp tmpfs rw,size=1g,mode=1777 0 0 # # UFS file system on a swap-backed md(4). /dev/md10 is # automatically created. If it is "md", a unit number # will be automatically selected. md10 /scratch mfs rw,-s1g 0 0 # # Swap space on a vnode-backed md(4). md11 none swap sw,file=/swapfile 0 0 # # CDROM. "noauto" option is typically used because the # media is removable. /dev/cd0 /cdrom cd9660 ro,noauto 0 0 # # NFS-exported file system. "serv" is an NFS server name # or IP address. serv:/export /nfs nfs rw,noinet6 0 0 .Ed .Sh SEE ALSO .Xr getfsent 3 , .Xr getvfsbyname 3 , .Xr strunvis 3 , .Xr ccd 4 , .Xr dump 8 , .Xr fsck 8 , .Xr geli 8 , .Xr mount 8 , .Xr quotacheck 8 , .Xr quotaon 8 , .Xr swapon 8 , .Xr umount 8 .Sh HISTORY The .Nm file format appeared in .Bx 4.0 .