1.\" Copyright (c) 1980, 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. 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.\" $FreeBSD$ 30.\" 31.Dd April 14, 2014 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 device or 64remote file system to be mounted. 65The contents are decoded by the 66.Xr strunvis 3 67function. 68This allows using spaces or tabs in the device name which would be 69interpreted as field separators otherwise. 70.Pp 71The second field, 72.Pq Fa fs_file , 73describes the mount point for the file system. 74For swap partitions, this field should be specified as 75.Dq none . 76The contents are decoded by the 77.Xr strunvis 3 78function, as above. 79.Pp 80The third field, 81.Pq Fa fs_vfstype , 82describes the type of the file system. 83The system can support various file system types. 84Only the root, /usr, and /tmp file systems need be statically 85compiled into the kernel; 86everything else will be automatically loaded at mount 87time. 88(Exception: the FFS cannot currently be demand-loaded.) 89Some people still prefer to statically 90compile other file systems as well. 91.Pp 92The fourth field, 93.Pq Fa fs_mntops , 94describes the mount options associated with the file system. 95It is formatted as a comma separated list of options. 96It contains at least the type of mount (see 97.Fa fs_type 98below) plus any additional options appropriate to the file system type. 99See the options flag 100.Pq Fl o 101in the 102.Xr mount 8 103page and the file system specific page, such as 104.Xr mount_nfs 8 , 105for additional options that may be specified. 106All options that can be given to the file system specific mount commands 107can be used in 108.Nm 109as well. 110They just need to be formatted a bit differently. 111The arguments of the 112.Fl o 113option can be used without the preceding 114.Fl o 115flag. 116Other options need both the file system specific flag and its argument, 117separated by an equal sign. 118For example, mounting an 119.Xr msdosfs 5 120filesystem, the options 121.Bd -literal -offset indent 122-o sync -o noatime -m 644 -M 755 -u foo -g bar 123.Ed 124.Pp 125should be written as 126.Bd -literal -offset indent 127sync,noatime,-m=644,-M=755,-u=foo,-g=bar 128.Ed 129.Pp 130in the option field of 131.Nm . 132.Pp 133If the options 134.Dq userquota 135and/or 136.Dq groupquota 137are specified, 138the file system is automatically processed by the 139.Xr quotacheck 8 140command, and user and/or group disk quotas are enabled with 141.Xr quotaon 8 . 142By default, 143file system quotas are maintained in files named 144.Pa quota.user 145and 146.Pa quota.group 147which are located at the root of the associated file system. 148These defaults may be overridden by putting an equal sign 149and an alternative absolute pathname following the quota option. 150Thus, if the user quota file for 151.Pa /tmp 152is stored in 153.Pa /var/quotas/tmp.user , 154this location can be specified as: 155.Bd -literal -offset indent 156userquota=/var/quotas/tmp.user 157.Ed 158.Pp 159If the option 160.Dq failok 161is specified, 162the system will ignore any error which happens during the mount of that filesystem, 163which would otherwise cause the system to drop into single user mode. 164This option is implemented by the 165.Xr mount 8 166command and will not be passed to the kernel. 167.Pp 168If the option 169.Dq noauto 170is specified, the file system will not be automatically 171mounted at system startup. 172Note that, for network file systems 173of third party types 174(i.e., types supported by additional software 175not included in the base system) 176to be automatically mounted at system startup, 177the 178.Va extra_netfs_types 179.Xr rc.conf 5 180variable must be used to extend the 181.Xr rc 8 182startup script's list of network file system types. 183.Pp 184If the option 185.Dq late 186is specified, the file system will be automatically mounted 187at a stage of system startup after remote mount points are mounted. 188For more detail about this option, 189see the 190.Xr mount 8 191manual page. 192.Pp 193If the option 194.Dq update 195is specified, it indicates that the status of an already mounted file 196system should be changed accordingly. 197This allows, for example, file systems mounted read-only to be upgraded 198read-write and vice-versa. 199By default, an entry corresponding to a file systems that is already 200mounted is going to be skipped over when processing 201.Nm , 202unless it's a root file system, in which case logic similar to 203.Dq update 204is applied automatically. 205.Pp 206The 207.Dq update 208option is typically used in conjuction with two 209.Nm 210files. 211The first 212.Nm 213file is used to set up the initial set of file systems. 214The second 215.Nm 216file is then run to update the initial set of file systems and 217to add additional file systems. 218.Pp 219The type of the mount is extracted from the 220.Fa fs_mntops 221field and stored separately in the 222.Fa fs_type 223field (it is not deleted from the 224.Fa fs_mntops 225field). 226If 227.Fa fs_type 228is 229.Dq rw 230or 231.Dq ro 232then the file system whose name is given in the 233.Fa fs_file 234field is normally mounted read-write or read-only on the 235specified special file. 236.Pp 237If 238.Fa fs_type 239is 240.Dq sw 241then the special file is made available as a piece of swap 242space by the 243.Xr swapon 8 244command at the end of the system reboot procedure. 245For swap devices, the keyword 246.Dq trimonce 247triggers the delivery of a 248.Dv BIO_DELETE 249command to the device to mark 250all blocks as unused. 251For vnode-backed swap spaces, 252.Dq file 253is supported in the 254.Fa fs_mntops 255field. 256When 257.Fa fs_spec 258is an 259.Xr md 4 260device file 261.Pq Do md Dc or Do md[0-9]* Dc 262and 263.Dq file 264is specified in 265.Fa fs_mntopts , 266an 267.Xr md 4 268device is created with the specified file used as backing store, 269and then the new device is used as swap space. 270Swap entries on 271.Pa .eli 272devices will cause automatic creation of encrypted devices. 273The 274.Dq ealgo , 275.Dq aalgo , 276.Dq keylen , 277.Dq notrim , 278and 279.Dq sectorsize 280options may be passed to control those 281.Xr geli 8 282parameters. 283The fields other than 284.Fa fs_spec 285and 286.Fa fs_type 287are unused. 288If 289.Fa fs_type 290is specified as 291.Dq xx 292the entry is ignored. 293This is useful to show disk partitions which are currently unused. 294.Pp 295The fifth field, 296.Pq Fa fs_freq , 297is used for these file systems by the 298.Xr dump 8 299command to determine which file systems need to be dumped. 300If the fifth field is not present, a value of zero is returned and 301.Nm dump 302will assume that the file system does not need to be dumped. 303If the fifth field is greater than 0, then it specifies the number of days 304between dumps for this file system. 305.Pp 306The sixth field, 307.Pq Fa fs_passno , 308is used by the 309.Xr fsck 8 310and 311.Xr quotacheck 8 312programs to determine the order in which file system and quota 313checks are done at reboot time. 314The 315.Fa fs_passno 316field can be any value between 0 and 317.Ql INT_MAX Ns -1 . 318.Pp 319The root file system should be specified with a 320.Fa fs_passno 321of 1, and other file systems should have a 322.Fa fs_passno 323of 2 or greater. 324A file system with a 325.Fa fs_passno 326value of 1 is always checked sequentially and be completed before 327another file system is processed, and it will be processed before 328all file systems with a larger 329.Fa fs_passno . 330.Pp 331For any given value of 332.Fa fs_passno , 333file systems within a drive will be checked sequentially, 334but file systems on different drives will be checked at the 335same time to utilize parallelism available in the hardware. 336Once all file system checks are complete for the current 337.Fa fs_passno , 338the same process will start over for the next 339.Fa fs_passno . 340.Pp 341If the sixth field is not present or is zero, 342a value of zero is returned and 343.Xr fsck 8 344and 345.Xr quotacheck 8 346will assume that the file system does not need to be checked. 347.Pp 348The 349.Fa fs_passno 350field can be used to implement finer control when 351the system utilities may determine that the file system resides 352on a different physical device, when it actually does not, as with a 353.Xr ccd 4 354device. 355All file systems with a lower 356.Fa fs_passno 357value will be completed before starting on file systems with a 358higher 359.Fa fs_passno 360value. 361E.g. all file systems with a 362.Fa fs_passno 363of 2 will be completed before any file systems with a 364.Fa fs_passno 365of 3 or greater are started. 366Gaps are allowed between the different 367.Fa fs_passno 368values. 369E.g. file systems listed in 370.Pa /etc/fstab 371may have 372.Fa fs_passno 373values such as 0, 1, 2, 15, 100, 200, 300, and may appear in any order 374within 375.Pa /etc/fstab . 376.Bd -literal 377#define FSTAB_RW "rw" /* read/write device */ 378#define FSTAB_RQ "rq" /* read/write with quotas */ 379#define FSTAB_RO "ro" /* read-only device */ 380#define FSTAB_SW "sw" /* swap device */ 381#define FSTAB_XX "xx" /* ignore totally */ 382 383struct fstab { 384 char *fs_spec; /* block special device name */ 385 char *fs_file; /* file system path prefix */ 386 char *fs_vfstype; /* File system type, ufs, nfs */ 387 char *fs_mntops; /* Mount options ala -o */ 388 char *fs_type; /* FSTAB_* from fs_mntops */ 389 int fs_freq; /* dump frequency, in days */ 390 int fs_passno; /* pass number on parallel fsck */ 391}; 392.Ed 393.Pp 394The proper way to read records from 395.Pa fstab 396is to use the routines 397.Xr getfsent 3 , 398.Xr getfsspec 3 , 399.Xr getfstype 3 , 400and 401.Xr getfsfile 3 . 402.Sh FILES 403.Bl -tag -width /etc/fstab -compact 404.It Pa /etc/fstab 405The file 406.Nm 407resides in 408.Pa /etc . 409.El 410.Sh EXAMPLES 411.Bd -literal 412# Device Mountpoint FStype Options Dump Pass# 413# 414# UFS file system. 415/dev/da0p2 / ufs rw 1 1 416# 417# Swap space on a block device. 418/dev/da0p1 none swap sw 0 0 419# 420# Swap space using a block device with GBDE/GELI encyption. 421# aalgo, ealgo, keylen, sectorsize options are available 422# for .eli devices. 423/dev/da1p1.bde none swap sw 0 0 424/dev/da1p2.eli none swap sw 0 0 425# 426# tmpfs. 427tmpfs /tmp tmpfs rw,size=1g,mode=1777 0 0 428# 429# UFS file system on a swap-backed md(4). /dev/md10 is 430# automatically created. If it is "md", a unit number 431# will be automatically selected. 432md10 /scratch mfs rw,-s1g 0 0 433# 434# Swap space on a vnode-backed md(4). 435md11 none swap sw,file=/swapfile 0 0 436# 437# CDROM. "noauto" option is typically used because the 438# media is removable. 439/dev/cd0 /cdrom cd9660 ro,noauto 0 0 440# 441# NFS-exported file system. "serv" is an NFS server name 442# or IP address. 443serv:/export /nfs nfs rw,noinet6 0 0 444.Ed 445.Sh SEE ALSO 446.Xr getfsent 3 , 447.Xr getvfsbyname 3 , 448.Xr strunvis 3 , 449.Xr ccd 4 , 450.Xr dump 8 , 451.Xr fsck 8 , 452.Xr geli 8 , 453.Xr mount 8 , 454.Xr quotacheck 8 , 455.Xr quotaon 8 , 456.Xr swapon 8 , 457.Xr umount 8 458.Sh HISTORY 459The 460.Nm 461file format appeared in 462.Bx 4.0 . 463