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

NAME
     fstab - static information about the filesystems

SYNOPSIS
     #include <fstab.h>

DESCRIPTION
     The fstab file 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 ffs, 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 an ``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 twelve types of filesystems:

           adosfs  An AmigaDOS filesystem.
           cd9660  An ISO9660 CD-ROM filesystem.
           fdesc   An implementation of /dev/fd.
           ffs     A local UNIX filesystem.
           ext2fs  A local Linux compatible ext2fs filesystem.
           kernfs  Various and sundry kernel statistics.
           mfs     A local memory-based UNIX filesystem.
           msdos   An MS-DOS FAT filesystem.
           nfs     A Sun Microsystems compatible Network File System.
           procfs  A local filesystem containing process information.
           swap    A disk partition to be used for swapping.
           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 addi-
     tional 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 at system boot
     time).

     If the options ``userquota'' and/or ``groupquota'' are specified, the
     filesystem is automatically processed by the quotacheck(8) command, and
     user and/or group disk quotas are enabled with quotaon(8). By default,
     filesystem quotas are maintained in files named quota.user and
     quota.group which are located at the root of the associated filesystem.
     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:

           userquota=/var/quotas/tmp.user

     The type of the mount is extracted from the first parameter of 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 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 is 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 fsck */
     };

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

EXAMPLES
     Here is a sample /etc/fstab file:

           /dev/sd0a / ffs rw 1 1
           /dev/sd0b none swap sw 0 0
           /dev/sd0e /var ffs rw 1 2
           #/dev/sd0f /tmp ffs rw 1 3
           /dev/sd0g /usr ffs rw 1 4
           /dev/sd0h /usr/local ffs rw 1 5
           /dev/sd0i /home ffs rw 1 6

           /dev/sd1b none swap sw 0 0
           /dev/cd0a /cdrom cd9660 ro,noauto 0 0

           /kern /kern kernfs ro 0 0
           /proc /proc procfs rw 0 0

FILES
     /etc/fstab

SEE ALSO
     getfsent(3)

HISTORY
     The fstab file format appeared in 4.0BSD.

OpenBSD 3.0                      June 5, 1993                                2
