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.Dd April 14, 2014 29.Dt FSTAB 5 30.Os 31.Sh NAME 32.Nm fstab 33.Nd static information about the file systems 34.Sh SYNOPSIS 35.In fstab.h 36.Sh DESCRIPTION 37The file 38.Nm 39contains descriptive information about the various file 40systems. 41.Nm 42is only read by programs, and not written; 43it is the duty of the system administrator to properly create 44and maintain this file. 45Each file system is described on a separate line; 46fields on each line are separated by tabs or spaces. 47The order of records in 48.Nm 49is important because 50.Xr fsck 8 , 51.Xr mount 8 , 52and 53.Xr umount 8 54sequentially iterate through 55.Nm 56doing their thing. 57.Pp 58The first field, 59.Pq Fa fs_spec , 60describes the special device or 61remote file system to be mounted. 62The contents are decoded by the 63.Xr strunvis 3 64function. 65This allows using spaces or tabs in the device name which would be 66interpreted as field separators otherwise. 67.Pp 68The second field, 69.Pq Fa fs_file , 70describes the mount point for the file system. 71For swap partitions, this field should be specified as 72.Dq none . 73The contents are decoded by the 74.Xr strunvis 3 75function, as above. 76.Pp 77The third field, 78.Pq Fa fs_vfstype , 79describes the type of the file system. 80The system can support various file system types. 81Only the root, /usr, and /tmp file systems need be statically 82compiled into the kernel; 83everything else will be automatically loaded at mount 84time. 85(Exception: the FFS cannot currently be demand-loaded.) 86Some people still prefer to statically 87compile other file systems as well. 88.Pp 89The fourth field, 90.Pq Fa fs_mntops , 91describes the mount options associated with the file system. 92It is formatted as a comma separated list of options. 93It contains at least the type of mount (see 94.Fa fs_type 95below) plus any additional options appropriate to the file system type. 96See the options flag 97.Pq Fl o 98in the 99.Xr mount 8 100page and the file system specific page, such as 101.Xr mount_nfs 8 , 102for additional options that may be specified. 103All options that can be given to the file system specific mount commands 104can be used in 105.Nm 106as well. 107They just need to be formatted a bit differently. 108The arguments of the 109.Fl o 110option can be used without the preceding 111.Fl o 112flag. 113Other options need both the file system specific flag and its argument, 114separated by an equal sign. 115For example, mounting an 116.Xr msdosfs 5 117filesystem, the options 118.Bd -literal -offset indent 119-o sync -o noatime -m 644 -M 755 -u foo -g bar 120.Ed 121.Pp 122should be written as 123.Bd -literal -offset indent 124sync,noatime,-m=644,-M=755,-u=foo,-g=bar 125.Ed 126.Pp 127in the option field of 128.Nm . 129.Pp 130If the options 131.Dq userquota 132and/or 133.Dq groupquota 134are specified, 135the file system is automatically processed by the 136.Xr quotacheck 8 137command, and user and/or group disk quotas are enabled with 138.Xr quotaon 8 . 139By default, 140file system quotas are maintained in files named 141.Pa quota.user 142and 143.Pa quota.group 144which are located at the root of the associated file system. 145These defaults may be overridden by putting an equal sign 146and an alternative absolute pathname following the quota option. 147Thus, if the user quota file for 148.Pa /tmp 149is stored in 150.Pa /var/quotas/tmp.user , 151this location can be specified as: 152.Bd -literal -offset indent 153userquota=/var/quotas/tmp.user 154.Ed 155.Pp 156If the option 157.Dq failok 158is specified, 159the system will ignore any error which happens during the mount of that filesystem, 160which would otherwise cause the system to drop into single user mode. 161This option is implemented by the 162.Xr mount 8 163command and will not be passed to the kernel. 164.Pp 165If the option 166.Dq noauto 167is specified, the file system will not be automatically 168mounted at system startup. 169Note that, for network file systems 170of third party types 171(i.e., types supported by additional software 172not included in the base system) 173to be automatically mounted at system startup, 174the 175.Va extra_netfs_types 176.Xr rc.conf 5 177variable must be used to extend the 178.Xr rc 8 179startup script's list of network file system types. 180.Pp 181If the option 182.Dq late 183is specified, the file system will be automatically mounted 184at a stage of system startup after remote mount points are mounted. 185For more detail about this option, 186see the 187.Xr mount 8 188manual page. 189.Pp 190If the option 191.Dq update 192is specified, it indicates that the status of an already mounted file 193system should be changed accordingly. 194This allows, for example, file systems mounted read-only to be upgraded 195read-write and vice-versa. 196By default, an entry corresponding to a file systems that is already 197mounted is going to be skipped over when processing 198.Nm , 199unless it's a root file system, in which case logic similar to 200.Dq update 201is applied automatically. 202.Pp 203The 204.Dq update 205option is typically used in conjunction with two 206.Nm 207files. 208The first 209.Nm 210file is used to set up the initial set of file systems. 211The second 212.Nm 213file is then run to update the initial set of file systems and 214to add additional file systems. 215.Pp 216The type of the mount is extracted from the 217.Fa fs_mntops 218field and stored separately in the 219.Fa fs_type 220field (it is not deleted from the 221.Fa fs_mntops 222field). 223If 224.Fa fs_type 225is 226.Dq rw 227or 228.Dq ro 229then the file system whose name is given in the 230.Fa fs_file 231field is normally mounted read-write or read-only on the 232specified special file. 233.Pp 234If 235.Fa fs_type 236is 237.Dq sw 238then the special file is made available as a piece of swap 239space by the 240.Xr swapon 8 241command at the end of the system reboot procedure. 242For swap devices, the keyword 243.Dq trimonce 244triggers the delivery of a 245.Dv BIO_DELETE 246command to the device. 247This command marks the device's blocks as unused, except those that 248might store a disk label. 249This marking can erase a crash dump. 250To delay 251.Nm swapon 252for a device until after 253.Nm savecore 254has copied the crash dump to another location, use the 255.Dq late 256option. 257For vnode-backed swap spaces, 258.Dq file 259is supported in the 260.Fa fs_mntops 261field. 262When 263.Fa fs_spec 264is an 265.Xr md 4 266device file 267.Pq Do md Dc or Do md[0-9]* Dc 268and 269.Dq file 270is specified in 271.Fa fs_mntopts , 272an 273.Xr md 4 274device is created with the specified file used as backing store, 275and then the new device is used as swap space. 276Swap entries on 277.Pa .eli 278devices will cause automatic creation of encrypted devices. 279The 280.Dq ealgo , 281.Dq aalgo , 282.Dq keylen , 283.Dq notrim , 284and 285.Dq sectorsize 286options may be passed to control those 287.Xr geli 8 288parameters. 289The fields other than 290.Fa fs_spec 291and 292.Fa fs_type 293are unused. 294If 295.Fa fs_type 296is specified as 297.Dq xx 298the entry is ignored. 299This is useful to show disk partitions which are currently unused. 300.Pp 301The fifth field, 302.Pq Fa fs_freq , 303is used for these file systems by the 304.Xr dump 8 305command to determine which file systems need to be dumped. 306If the fifth field is not present, a value of zero is returned and 307.Nm dump 308will assume that the file system does not need to be dumped. 309If the fifth field is greater than 0, then it specifies the number of days 310between dumps for this file system. 311.Pp 312The sixth field, 313.Pq Fa fs_passno , 314is used by the 315.Xr fsck 8 316and 317.Xr quotacheck 8 318programs to determine the order in which file system and quota 319checks are done at reboot time. 320The 321.Fa fs_passno 322field can be any value between 0 and 323.Ql INT_MAX Ns -1 . 324.Pp 325The root file system should be specified with a 326.Fa fs_passno 327of 1, and other file systems should have a 328.Fa fs_passno 329of 2 or greater. 330A file system with a 331.Fa fs_passno 332value of 1 is always checked sequentially and be completed before 333another file system is processed, and it will be processed before 334all file systems with a larger 335.Fa fs_passno . 336.Pp 337For any given value of 338.Fa fs_passno , 339file systems within a drive will be checked sequentially, 340but file systems on different drives will be checked at the 341same time to utilize parallelism available in the hardware. 342Once all file system checks are complete for the current 343.Fa fs_passno , 344the same process will start over for the next 345.Fa fs_passno . 346.Pp 347If the sixth field is not present or is zero, 348a value of zero is returned and 349.Xr fsck 8 350and 351.Xr quotacheck 8 352will assume that the file system does not need to be checked. 353.Pp 354The 355.Fa fs_passno 356field can be used to implement finer control when 357the system utilities may determine that the file system resides 358on a different physical device, when it actually does not, as with a 359.Xr ccd 4 360device. 361All file systems with a lower 362.Fa fs_passno 363value will be completed before starting on file systems with a 364higher 365.Fa fs_passno 366value. 367E.g. all file systems with a 368.Fa fs_passno 369of 2 will be completed before any file systems with a 370.Fa fs_passno 371of 3 or greater are started. 372Gaps are allowed between the different 373.Fa fs_passno 374values. 375E.g. file systems listed in 376.Pa /etc/fstab 377may have 378.Fa fs_passno 379values such as 0, 1, 2, 15, 100, 200, 300, and may appear in any order 380within 381.Pa /etc/fstab . 382.Bd -literal 383#define FSTAB_RW "rw" /* read/write device */ 384#define FSTAB_RQ "rq" /* read/write with quotas */ 385#define FSTAB_RO "ro" /* read-only device */ 386#define FSTAB_SW "sw" /* swap device */ 387#define FSTAB_XX "xx" /* ignore totally */ 388 389struct fstab { 390 char *fs_spec; /* block special device name */ 391 char *fs_file; /* file system path prefix */ 392 char *fs_vfstype; /* File system type, ufs, nfs */ 393 char *fs_mntops; /* Mount options ala -o */ 394 char *fs_type; /* FSTAB_* from fs_mntops */ 395 int fs_freq; /* dump frequency, in days */ 396 int fs_passno; /* pass number on parallel fsck */ 397}; 398.Ed 399.Pp 400The proper way to read records from 401.Pa fstab 402is to use the routines 403.Xr getfsent 3 , 404.Xr getfsspec 3 , 405.Xr getfstype 3 , 406and 407.Xr getfsfile 3 . 408.Sh FILES 409.Bl -tag -width /etc/fstab -compact 410.It Pa /etc/fstab 411The file 412.Nm 413resides in 414.Pa /etc . 415.El 416.Sh EXAMPLES 417.Bd -literal 418# Device Mountpoint FStype Options Dump Pass# 419# 420# UFS file system. 421/dev/da0p2 / ufs rw 1 1 422# 423# Swap space on a block device. 424/dev/da0p1 none swap sw 0 0 425# 426# Swap space using a block device with GBDE/GELI encryption. 427# aalgo, ealgo, keylen, sectorsize options are available 428# for .eli devices. 429/dev/da1p1.bde none swap sw 0 0 430/dev/da1p2.eli none swap sw 0 0 431# 432# tmpfs. 433tmpfs /tmp tmpfs rw,size=1g,mode=1777 0 0 434# 435# UFS file system on a swap-backed md(4). /dev/md10 is 436# automatically created. If it is "md", a unit number 437# will be automatically selected. 438md10 /scratch mfs rw,-s1g 0 0 439# 440# Swap space on a vnode-backed md(4). 441md11 none swap sw,file=/swapfile 0 0 442# 443# CDROM. "noauto" option is typically used because the 444# media is removable. 445/dev/cd0 /cdrom cd9660 ro,noauto 0 0 446# 447# NFS-exported file system. "serv" is an NFS server name 448# or IP address. 449serv:/export /nfs nfs rw,noinet6 0 0 450.Ed 451.Sh SEE ALSO 452.Xr getfsent 3 , 453.Xr getvfsbyname 3 , 454.Xr strunvis 3 , 455.Xr ccd 4 , 456.Xr dump 8 , 457.Xr fsck 8 , 458.Xr geli 8 , 459.Xr mount 8 , 460.Xr quotacheck 8 , 461.Xr quotaon 8 , 462.Xr swapon 8 , 463.Xr umount 8 464.Sh HISTORY 465The 466.Nm 467file format appeared in 468.Bx 4.0 . 469