MNTENT(5)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, 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 filesystem (such as floppy disk) is removable, or ro
if a filesystem is read-only. See mount(8) for a more complete
description 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.
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
format 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, indicating 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 partitions.
/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 ALSOfsck(8), getmntent(3), mount(8), quotacheck(8), quotaon(8), umount(8)
May 19, 1986 MNTENT(5)
