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FSTAB(5)		    BSD	File Formats Manual		      FSTAB(5)

     fstab -- static information about the file	systems

     #include <fstab.h>

     The file fstab contains descriptive information about the various file
     systems.  fstab 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 fstab is important
     because fsck(8), mount(8),	and umount(8) sequentially iterate through
     fstab doing their thing.

     The first field, (fs_spec), describes the special device or remote	file
     system to be mounted.

     The second	field, (fs_file), describes the	mount point for	the file sys-
     tem.  For swap partitions,	this field should be specified as ``none''.

     The third field, (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;	every-
     thing else	will be	automatically loaded at	mount time.  (Exception: the
     UFS family	- FFS and LFS cannot currently be demand-loaded.)  Some	people
     still prefer to statically	compile	other file systems as well.

     The fourth	field, (fs_mntops), describes the mount	options	associated
     with the file system.  It is formatted as a comma separated list of op-
     tions.  It	contains at least the type of mount (see fs_type below)	plus
     any additional options appropriate	to the file system type.  See the op-
     tions flag	(-o) in	the mount(8) page and the file system specific page,
     such as 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	fstab as well.	They just need to be formatted a bit differ-
     ently.  The arguments of the -o option can	be used	without	the preceding
     -o	flag.  Other options need both the file	system specific	flag and its
     argument, separated by an equal sign.  For	example, mounting an
     msdosfs(5)	filesystem, the	options

	   -o sync -o noatime -m 644 -M	755 -u foo -g bar

     should be written as


     in	the option field of fstab.

     If	the options ``userquota'' and/or ``groupquota''	are specified, the
     file system is automatically processed by the quotacheck(8) command, and
     user and/or group disk quotas are enabled with quotaon(8).	 By default,
     file system quotas	are maintained in files	named quota.user and which are located at the root of the associated file system.
     These defaults may	be overridden by putting an equal sign and an alterna-
     tive absolute pathname following the quota	option.	 Thus, if the user
     quota file	for /tmp is stored in /var/quotas/tmp.user, this location can
     be	specified as:


     If	the option ``noauto'' is specified, the	file system will not be	auto-
     matically 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 extra_netfs_types rc.conf(5) variable	must be	used to	extend
     the rc(8) startup script's	list of	network	file system types.

     The type of the mount is extracted	from the fs_mntops field and stored
     separately	in the fs_type field (it is not	deleted	from the fs_mntops
     field).  If fs_type is ``rw'' or ``ro'' then the file system whose	name
     is	given in the fs_file field is normally mounted read-write or read-only
     on	the specified special file.  If	fs_type	is ``sw'' then the special
     file is made available as a piece of swap space by	the swapon(8) command
     at	the end	of the system reboot procedure.	 The fields other than fs_spec
     and fs_type are unused.  If fs_type is specified as ``xx''	the entry is
     ignored.  This is useful to show disk partitions which are	currently un-

     The fifth field, (fs_freq), is used for these file	systems	by the 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 dump	will assume
     that the file system does not need	to be dumped.

     The sixth field, (fs_passno), is used by the fsck(8) and quotacheck(8)
     programs to determine the order in	which file system and quota checks are
     done at reboot time.  The fs_passno field can be any value	between	0 and

     The root file system should be specified with a fs_passno of 1, and other
     file systems should have a	fs_passno of 2 or greater.  A file system with
     a 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 fs_passno.

     For any given value of 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 hard-
     ware.  Once all file system checks	are complete for the current
     fs_passno,	the same process will start over for the next fs_passno.

     If	the sixth field	is not present or is zero, a value of zero is returned
     and fsck(8) and quotacheck(8) will	assume that the	file system does not
     need to be	checked.

     The fs_passno field can be	used to	implement finer	control	when the sys-
     tem utilities may determine that the file system resides on a different
     physical device, when it actually does not, as with a ccd(4) device.  All
     file systems with a lower fs_passno value will be completed before	start-
     ing on file systems with a	higher fs_passno value.	 E.g. all file systems
     with a fs_passno of 2 will	be completed before any	file systems with a
     fs_passno of 3 or greater are started.  Gaps are allowed between the dif-
     ferent fs_passno values.  E.g. file systems listed	in /etc/fstab may have
     fs_passno values such as 0, 1, 2, 15, 100,	200, 300, and may appear in
     any order within /etc/fstab.

     #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 */

     The proper	way to read records from fstab is to use the routines
     getfsent(3), getfsspec(3),	getfstype(3), and getfsfile(3).

     /etc/fstab	 The file fstab	resides	in /etc.

     getfsent(3), getvfsbyname(3), ccd(4), dump(8), fsck(8), mount(8),
     quotacheck(8), quotaon(8),	swapon(8), umount(8)

     The fstab file format appeared in 4.0BSD.

BSD			       November	23, 2008			   BSD


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