MNTENT(5) UNIX Programmer's Manual MNTENT(5)
NAME
mntent, fstab - static information about filesystems
SYNOPSIS
#include <mntent.h>
DESCRIPTION
NOTE: Unless NetInfo is disabled, /etc/fstab is accessed
only at boot time, when it's used to mount all file systems
of type 4.3.
The file /etc/fstab describes the file systems and swapping
partitions used by the local machine. It is created by the
system administrator using a text editor, and processed by
commands which mount, unmount, check consistency of, dump
and restore file systems, and by the system in providing
swap space.
It consists of a number of lines of the form:
fsname dir type opts freq passno
an example of which would be:
/dev/xy0a / 4.3 rw,noquota 1 2
The entries in this file are accessed using the routines in
getmntent(3), which returns a structure of the following
form:
struct mntent {
char *mnt_fsname; /* file system name */
char *mnt_dir; /* file system path prefix */
char *mnt_type; /* 4.3, nfs, dos, macintosh, nucfs, cfs, or ignore */
char *mnt_opts; /* ro, etc. */
int mnt_freq; /* dump frequency, in days */
int mnt_passno; /* pass number on parallel fsck */
};
There is one entry per line in the file, and the fields are
separated by white space. A ``#'' as the first non-white
character indicates a comment.
The mnt_opts field consists of a string of comma separated
options. Some of the options are common to all filesystem
types, and others only make sense for a single filesystem
type. It is important to specify that a removable filesys-
tem (such as floppy disk) is removable, or ro if a filesys-
tem is read-only. See mount(8) for a more complete descrip-
tion of the options available.
The mnt_type field determines how the mnt_fsname, and
mnt_opts fields will be interpreted. Below is a list of the
file system types currently supported and the way each of
them interprets these fields. See
/NextDeveloper/Headers/bsd/mntent.h for additional, though
unsupported, file system types.
4.3
mnt_fsname Must be a block special device.
mnt_opts Valid opts are: ro, rw, suid, nosuid.
nfs
mnt_fsname servername:volumename to be mounted
mnt_opts Valid opts are: ro, rw, nosuid, hard, soft,
bg, fg, retry, rsize, wsize, timeo,
retrans, port, intr, net, secure, grpid,
nosub, multi, acregmin, acregmax, noac,
acdirmin, acdirmax.
dos
mnt_fsname Must be a raw device.
mnt_opts Ignored.
NOTE: This file system does not support SCSI hard
disks, CD-ROMs, or 2.88 MB floppies; it supports only
720KB and 1.4 MB floppies. To mount a dos volume, the
appropriate loadable kernel server must already be
loaded into the system.
macintosh
mnt_fsname Must be a raw device.
mnt_opts Ignored.
NOTE: To mount a macintosh volume, the appropriate
loadable kernel server must already be loaded into the
system.
nucfs (NetWare UNIX Client file system)
mnt_fsname servername:volumename to be mounted
mnt_opts Valid opts are: ro, uid=someuser.
NOTE: To mount a nucfs volume you must be root. In
addition, either root must be authenticated to the
NetWare server, or the mount option uid=someuser must
be included to specify the UNIX user name or uid of a
NeXT user who is already authenticated to the NetWare
server.
cfs (CD-ROM file system)
mnt_fsname Must be a raw device.
mnt_opts Ignored.
NOTE: To mount a cfs volume, the appropriate loadable
kernel server must already be loaded into the system.
If the mnt_type is specified as ``ignore'' the entry is
ignored. This is useful to show disk partitions which are
currently not used. Disks that are specified as as
``ignore'' are also not automounted by the Workspace in
NEXTSTEP. This is useful when your disk has data in a for-
mat that NEXTSTEP doesn't recognize, and you want it to
ignore the disk.
The field mnt_freq indicates how often each partition should
be dumped by the dump(8) command (and triggers that
command's w option which tells which file systems should be
dumped). Most systems set the mnt_freq field to 1, indicat-
ing that the file systems are dumped each day.
The final field mnt_passno is used by the disk consistency
check program fsck(8) to allow overlapped checking of file
systems during a reboot. All file systems with mnt_passno
of 1 are first checked simultaneously, then all file systems
with mnt_passno of 2, and so on. It is usual to make the
mnt_passno of the root file system have the value 1, and
then check one file system on each available disk drive in
each subsequent pass to the exhaustion of file system parti-
tions.
/etc/fstab is only read by programs, and not written; it is
the duty of the system administrator to properly create and
maintain this file. The order of records in /etc/fstab is
important because fsck, mount, and umount process the file
sequentially; file systems must appear after file systems
they are mounted within.
FILES
/etc/fstab
SEE ALSO
fsck(8), getmntent(3), mount(8), quotacheck(8), quotaon(8),
umount(8)