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 193The type of the mount is extracted from the 194.Fa fs_mntops 195field and stored separately in the 196.Fa fs_type 197field (it is not deleted from the 198.Fa fs_mntops 199field). 200If 201.Fa fs_type 202is 203.Dq rw 204or 205.Dq ro 206then the file system whose name is given in the 207.Fa fs_file 208field is normally mounted read-write or read-only on the 209specified special file. 210.Pp 211If 212.Fa fs_type 213is 214.Dq sw 215then the special file is made available as a piece of swap 216space by the 217.Xr swapon 8 218command at the end of the system reboot procedure. 219For swap devices, the keyword 220.Dq trimonce 221triggers the delivery of a 222.Dv BIO_DELETE 223command to the device to mark 224all blocks as unused. 225For vnode-backed swap spaces, 226.Dq file 227is supported in the 228.Fa fs_mntops 229field. 230When 231.Fa fs_spec 232is an 233.Xr md 4 234device file 235.Pq Do md Dc or Do md[0-9]* Dc 236and 237.Dq file 238is specified in 239.Fa fs_mntopts , 240an 241.Xr md 4 242device is created with the specified file used as backing store, 243and then the new device is used as swap space. 244Swap entries on 245.Pa .eli 246devices will cause automatic creation of encrypted devices. 247The 248.Dq ealgo , 249.Dq aalgo , 250.Dq keylen , 251.Dq notrim , 252and 253.Dq sectorsize 254options may be passed to control those 255.Xr geli 8 256parameters. 257The fields other than 258.Fa fs_spec 259and 260.Fa fs_type 261are unused. 262If 263.Fa fs_type 264is specified as 265.Dq xx 266the entry is ignored. 267This is useful to show disk partitions which are currently unused. 268.Pp 269The fifth field, 270.Pq Fa fs_freq , 271is used for these file systems by the 272.Xr dump 8 273command to determine which file systems need to be dumped. 274If the fifth field is not present, a value of zero is returned and 275.Nm dump 276will assume that the file system does not need to be dumped. 277If the fifth field is greater than 0, then it specifies the number of days 278between dumps for this file system. 279.Pp 280The sixth field, 281.Pq Fa fs_passno , 282is used by the 283.Xr fsck 8 284and 285.Xr quotacheck 8 286programs to determine the order in which file system and quota 287checks are done at reboot time. 288The 289.Fa fs_passno 290field can be any value between 0 and 291.Ql INT_MAX Ns -1 . 292.Pp 293The root file system should be specified with a 294.Fa fs_passno 295of 1, and other file systems should have a 296.Fa fs_passno 297of 2 or greater. 298A file system with a 299.Fa fs_passno 300value of 1 is always checked sequentially and be completed before 301another file system is processed, and it will be processed before 302all file systems with a larger 303.Fa fs_passno . 304.Pp 305For any given value of 306.Fa fs_passno , 307file systems within a drive will be checked sequentially, 308but file systems on different drives will be checked at the 309same time to utilize parallelism available in the hardware. 310Once all file system checks are complete for the current 311.Fa fs_passno , 312the same process will start over for the next 313.Fa fs_passno . 314.Pp 315If the sixth field is not present or is zero, 316a value of zero is returned and 317.Xr fsck 8 318and 319.Xr quotacheck 8 320will assume that the file system does not need to be checked. 321.Pp 322The 323.Fa fs_passno 324field can be used to implement finer control when 325the system utilities may determine that the file system resides 326on a different physical device, when it actually does not, as with a 327.Xr ccd 4 328device. 329All file systems with a lower 330.Fa fs_passno 331value will be completed before starting on file systems with a 332higher 333.Fa fs_passno 334value. 335E.g. all file systems with a 336.Fa fs_passno 337of 2 will be completed before any file systems with a 338.Fa fs_passno 339of 3 or greater are started. 340Gaps are allowed between the different 341.Fa fs_passno 342values. 343E.g. file systems listed in 344.Pa /etc/fstab 345may have 346.Fa fs_passno 347values such as 0, 1, 2, 15, 100, 200, 300, and may appear in any order 348within 349.Pa /etc/fstab . 350.Bd -literal 351#define FSTAB_RW "rw" /* read/write device */ 352#define FSTAB_RQ "rq" /* read/write with quotas */ 353#define FSTAB_RO "ro" /* read-only device */ 354#define FSTAB_SW "sw" /* swap device */ 355#define FSTAB_XX "xx" /* ignore totally */ 356 357struct fstab { 358 char *fs_spec; /* block special device name */ 359 char *fs_file; /* file system path prefix */ 360 char *fs_vfstype; /* File system type, ufs, nfs */ 361 char *fs_mntops; /* Mount options ala -o */ 362 char *fs_type; /* FSTAB_* from fs_mntops */ 363 int fs_freq; /* dump frequency, in days */ 364 int fs_passno; /* pass number on parallel fsck */ 365}; 366.Ed 367.Pp 368The proper way to read records from 369.Pa fstab 370is to use the routines 371.Xr getfsent 3 , 372.Xr getfsspec 3 , 373.Xr getfstype 3 , 374and 375.Xr getfsfile 3 . 376.Sh FILES 377.Bl -tag -width /etc/fstab -compact 378.It Pa /etc/fstab 379The file 380.Nm 381resides in 382.Pa /etc . 383.El 384.Sh EXAMPLES 385.Bd -literal 386# Device Mountpoint FStype Options Dump Pass# 387# 388# UFS file system. 389/dev/da0p2 / ufs rw 1 1 390# 391# Swap space on a block device. 392/dev/da0p1 none swap sw 0 0 393# 394# Swap space using a block device with GBDE/GELI encyption. 395# aalgo, ealgo, keylen, sectorsize options are available 396# for .eli devices. 397/dev/da1p1.bde none swap sw 0 0 398/dev/da1p2.eli none swap sw 0 0 399# 400# tmpfs. 401tmpfs /tmp tmpfs rw,size=1g,mode=1777 0 0 402# 403# UFS file system on a swap-backed md(4). /dev/md10 is 404# automatically created. If it is "md", a unit number 405# will be automatically selected. 406md10 /scratch mfs rw,-s1g 0 0 407# 408# Swap space on a vnode-backed md(4). 409md11 none swap sw,file=/swapfile 0 0 410# 411# CDROM. "noauto" option is typically used because the 412# media is removable. 413/dev/cd0 /cdrom cd9660 ro,noauto 0 0 414# 415# NFS-exported file system. "serv" is an NFS server name 416# or IP address. 417serv:/export /nfs nfs rw,noinet6 0 0 418.Ed 419.Sh SEE ALSO 420.Xr getfsent 3 , 421.Xr getvfsbyname 3 , 422.Xr strunvis 3 , 423.Xr ccd 4 , 424.Xr dump 8 , 425.Xr fsck 8 , 426.Xr geli 8 , 427.Xr mount 8 , 428.Xr quotacheck 8 , 429.Xr quotaon 8 , 430.Xr swapon 8 , 431.Xr umount 8 432.Sh HISTORY 433The 434.Nm 435file format appeared in 436.Bx 4.0 . 437