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) 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
     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
     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).

EXAMPLES

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

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