2.11BSD#431 - /usr/man/cat5/fstab.0

FSTAB(5)	    UNIX Programmer's 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 fsck(8), mount(8), and umount(8)
     sequentially iterate through fstab doing their thing.

     The first field, fs_spec, describes the block special device
     or remote filesystem to be mounted.  For filesystems of type
     ufs, the special file name is the block special file name,
     and not the character special file name.  If a program needs
     the character special file name, the program must create it
     by appending a ``r'' after the last ``/'' in the special
     file name.

     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 only two types of
     filesystems:

     ufs	    a local UNIX filesystem

     swap	    a disk partition to be used for swapping

     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.

     If the option ``quotas'' is specified, the filesystem is
     automatically processed by the quotacheck(8) command, and
     user disk quotas are enabled with quotaon(8).  Filesystem
     quotas are maintained in the file named quotas located at
     the root of the associated filesystem.  This restriction on
     the location of the quotas file is needlessly imposed by the
     kernel but may be lifted in the future.  Thus, if the user
     quota file for /tmp is stored in /var/quotas/tmp.user, this
     location can be specified as:


Printed 11/26/99	January 15, 1996			1


FSTAB(5)	    UNIX Programmer's Manual		 FSTAB(5)


	    quotas=/var/quotas/tmp.user

     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 pro-
     cedure.  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(8) 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(8) 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 dump */
     };

     The proper way to read records from fstab is to use the rou-
     tines getfsent(3), getfsspec(3), getfstype(3), and getfs-
     file(3).


Printed 11/26/99	January 15, 1996			2


FSTAB(5)	    UNIX Programmer's Manual		 FSTAB(5)


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

SEE ALSO
     getfsent(3)

HISTORY
     The fstab file format appeared in 4.0BSD.


Printed 11/26/99	January 15, 1996			3