opendarwin man page for fstab

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

NAME
     fstab -- static information about the filesystems

SYNOPSIS
     #include <fstab.h>

DESCRIPTION
     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) sequentially 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 hard-
     ware configuration and of hardware parallelism, using the constructs ``UUID'' and ``LABEL''.

     The second field, (fs_file), describes the mount point for the filesystem.  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
     options.  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 time).

     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 unused.

     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 filesystems 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).

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

SEE ALSO
     getfsent(3), diskarbitrationd(8)

HISTORY
     The fstab file format appeared in 4.0BSD.

Darwin								  March 28, 2002							    Darwin