2.11BSD/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, _f_s__s_p_e_c, describes the block special device
or remote filesystem to be mounted. For filesystems of type
_u_f_s, 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, _f_s__f_i_l_e, describes the mount point for the
filesystem. For swap partitions, this field should be
specified as ``none''.
The third field, _f_s__v_f_s_t_y_p_e, describes the type of the
filesystem. The system currently supports only two types of
filesystems:
_u_f_s a local UNIX filesystem
_s_w_a_p a disk partition to be used for swapping
The fourth field, _f_s__m_n_t_o_p_s, 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 _f_s__t_y_p_e 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 _q_u_o_t_a_s 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 /_t_m_p is stored in /_v_a_r/_q_u_o_t_a_s/_t_m_p._u_s_e_r, this
location can be specified as:
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FSTAB(5) UNIX Programmer's Manual FSTAB(5)
quotas=/var/quotas/tmp.user
The type of the mount is extracted from the _f_s__m_n_t_o_p_s field
and stored separately in the _f_s__t_y_p_e field (it is not
deleted from the _f_s__m_n_t_o_p_s field). If _f_s__t_y_p_e is ``rw'' or
``ro'' then the filesystem whose name is given in the
_f_s__f_i_l_e field is normally mounted read-write or read-only on
the specified special file. If _f_s__t_y_p_e 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 _f_s__s_p_e_c and _f_s__t_y_p_e are
unused. If _f_s__t_y_p_e is specified as ``xx'' the entry is
ignored. This is useful to show disk partitions which are
currently unused.
The fifth field, _f_s__f_r_e_q, 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, _f_s__p_a_s_s_n_o, 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 _f_s__p_a_s_s_n_o of 1, and other filesystems should have a
_f_s__p_a_s_s_n_o 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 _f_s_t_a_b is to use the rou-
tines getfsent(3), getfsspec(3), getfstype(3), and getfs-
file(3).
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FSTAB(5) UNIX Programmer's Manual FSTAB(5)
FILES
/_e_t_c/_f_s_t_a_b The file fstab resides in /_e_t_c.
SEE ALSO
getfsent(3)
HISTORY
The fstab file format appeared in 4.0BSD.
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