FSTAB(5) OpenBSD 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 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 a ``r'' after the last ``/'' in the special
file name.
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 eleven types of filesystems:
adosfs An AmigaDOS filesystem
cd9660 an ISO 9660 CD-ROM filesystem
fdesc an implementation of /dev/fd
ffs a local UNIX filesystem
kernfs various and sundry kernel statistics
mfs a local memory-based UNIX filesystem
msdos a MSDOS ``FAT'' filesystem
nfs a Sun Microsystems compatible ``Network File System''
procfs a local filesystem of 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 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
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 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)
HISTORY
The fstab file format appeared in 4.0BSD.
4th Berkeley Distribution June 5, 1993 2