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

     fstab -- static information about the filesystems

     #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 filesystem 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 diskarbitrationd(8), fsck(8), mount(8), and umount(8) sequen-
     tially iterate through fstab doing	their thing.

     The first field, (fs_spec), describes the block special device, the local
     filesystem, or the	remote filesystem to be	mounted.  The diskarbitrationd
     program supports the identification of a local filesystem uniquely	by its
     UUID or by	its volume name, irrespective of hardware configuration	and of
     hardware parallelism, using the constructs	``UUID'' and ``LABEL''.

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

     The third field, (fs_vfstype), describes the type of the filesystem.  The
     system currently supports these types of filesystems:

	   ufs	   a local UNIX	filesystem

	   nfs	   a Sun Microsystems compatible ``Network File	System''

	   swap	   a disk partition to be used for swapping

	   msdos   a DOS compatible filesystem

	   cd9660  a CD-ROM filesystem (as per ISO 9660)

	   procfs  a file system for accessing process data

	   kernfs  a file system for accessing kernel parameters

	   fdesc   an implementation of	/dev/fd

	   union   a translucent filesystem

     The fourth	field, (fs_mntops), describes the mount	options	associated
     with the filesystem.  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 filesystem type.

     The option	``auto'' can be	used in	the ``noauto'' form to cause a file
     system not	to be mounted automatically (with ``mount -a'',	or system boot

     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 filesystem 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 filesystems by the dump(8)
     command to	determine which	filesystems need to be dumped.	If the fifth
     field is not present, a value of zero is returned and dump	will assume
     that the filesystem does not need to be dumped.

     The sixth field, (fs_passno), is used by the fsck(8) program to determine
     the order in which	filesystem checks are done at reboot time.  The	root
     filesystem	should be specified with a fs_passno of	1, and other filesys-
     tems should have a	fs_passno of 2.	 Filesystems within a drive will be
     checked sequentially, but filesystems on different	drives will be checked
     at	the same time to utilize parallelism available in the hardware.	 If
     the sixth field is	not present or zero, a value of	zero is	returned and
     fsck will assume that the filesystem does not need	to be checked.

     #define FSTAB_RW	     "rw"    /*	read-write device */
     #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;	     /*	filesystem path	prefix */
	     char    *fs_vfstype;    /*	type of	filesystem */
	     char    *fs_mntops;     /*	comma separated	mount options */
	     char    *fs_type;	     /*	rw, ro,	sw, or xx */
	     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).

     UUID=DF000C7E-AE0C-3B15-B730-DFD2EF15CB91 /export ufs   ro
     UUID=FAB060E9-79F7-33FF-BE85-E1D3ABD3EDEA none    hfs   rw,noauto LA-
     BEL=The\040Volume\040Name\040Is\040This none    msdos ro

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

     getfsent(3), diskarbitrationd(8)

     The fstab file format appeared in 4.0BSD.

Darwin				March 28, 2002				Darwin


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