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fstab(4)
NAME
fstab - Static information about mounted file systems
SYNOPSIS
/etc/fstab
DESCRIPTION
The /etc/fstab file contains descriptive information about the known file
systems and the disk partitions used. In Tru64 UNIX Version 5.0, the
descriptive information for partitions used in swapping and dumping moved
to the /etc/sysconfigtab file. The /etc/fstab file is read by various
programs. When you install the operating system, the local file systems
are included in the /etc/fstab file. Each file system is described on a
separate line; fields on each line are separated by tabs or spaces. When
you boot the system, only the file systems specified in the /etc/fstab file
are mounted.
The following is an example of an /etc/fstab file:
/dev/disk/dsk2a / ufs rw 1 1
/dev/disk/dsk0g /usr ufs rw 1 2
/dev/disk/dsk2g /var ufs rw 1 2
/dev/disk/dsk3c /usr/users ufs rw 1 2
/usr/share/man@rabbit /usr/share/man nfs ro,bg 0 0
usr_dmn#user1 /usr/user1 advfs rw,userquota,groupquota 0 2
The order of the lines in the /etc/fstab file is important because the
fsck, mount, and umount commands read the file sequentially from top to
bottom.
The syntax of a line in the /etc/fstab file is as follows. Note that lines
beginning with a hash (#) sign are ignored. Blank lines are also ignored.
file_spec mnt_point fs_type mnt_options backup fsck
The first field, (file_spec), describes the block special device, the
remote file system directory, or the AdvFS fileset to be mounted. For UFS
file systems, 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 inserting the letter r in the
appropriate place in the device special file name. For example,
/dev/rdisk/dsk0g. For mfs file systems, file_spec can also specify switches
to the mfs command, separated by commas. For example, you can specify a
size of 1024 sectors and the number of bytes per inode as 1024 by passing
the following arguments:
-s1024,-i2048 /mfsdir mfs rw
See mfs(8) for more information.
The second field, (mnt_point), specifies the mount point for the file
system or remote directory.
The third field, (fs_type), specifies the type of file system. The system
currently supports the following file systems:
cdfs
Specifies an ISO 9660 or High Sierra Formatted (CD-ROM) file system.
dvdfs
Specifies a Universal Disk Format (UDF) formatted file system.
nfs Specifies a Network File System (NFS) protocol. The mount command tries
a Version 3 mount first. If does not get a response, it then tries a
Version 2 mount. See mount(8) for more information on NFS mount
options.
procfs
Specifies a /proc file system, which allows you to access and
manipulate running processes as if they were files. The /proc file
system is used for debugging purposes. You must specify 0 (zero) in
the freq and order fields because the /proc file system should not be
backed up or checked.
ufs Specifies a local UNIX file system (Berkeley fast file system).
mfs Specifies the memory file system (RAM Disk). (See mfs(8).)
advfs
Specifies a local Advanced File System (AdvFS).
pcfs
Specifies the PC File System.
dfs Specifies the DCE Distributed File System.
efs Specifies the DCE Episode File System.
ffm Specifies the File on File Mounting system (used by streams).
fdfs
Specifies the File Descriptor File System (used by streams).
nfsv3
Specifies the Network File System (NFS) Version 3 protocol.
The fourth field, (mnt_options), describes the mount options associated
with the file system or partition. It is formatted as a comma separated
list of options and must contain, at a minimum, one of the mount options
ro, rq, or rw. You cannot use the options dirty, userquota, or groupquota
unless you also specify one of the minimum options.
ro Specifies that the file system is mounted with read-only access.
rq Specifies that the file system is mounted with read-write access.
rw Specifies that the file system is mounted with read-write access.
dirty
Specifies that the file system can be mounted even if it was not
cleanly unmounted. This is only for UFS.
userquota [=filename] and groupquota [=filename]
If quotas are to be enforced for users or groups, one or both of the
options must be specified. If userquota is specified, user quotas are
to be enforced. If groupquota is specified, group quotas are to be
enforced. See also quotaon(8) and quotaoff(8).
These options can also specify the location of the quota files; either
userquota, groupquota, or both can be specified. When the quota
commands (for example, quotacheck and quotaon) are run, they first
access the quota files. By default, user and group quotas for a file
system are contained in the quota.user and quota.group files, which are
located in the directory specified by the mount point. For example, the
quotas for the file system on which /usr is mounted are located in the
/usr directory. You also can specify another file name and location.
For example:
userquota=/var/quotas/tmp.user
Note that quota options apply only to UFS and AdvFS file systems.
xx Specifies that the file system entry should be ignored.
There are no default mount options. The mount operation fails if you do not
specify a mount option or if you specify an incorrect mount option. See
mount(8) for a complete list and description of valid mount options for the
various file system types.
The fifth field, (backup), is used by the dump command to determine which
file systems need to be backed up. If the fifth field is not present, a
value of zero is returned and dump assumes that the file system does not
need to be backed up. AdvFS ignores this field.
For UFS file systems, the sixth field, (pass number), is used by the fsck
and quotacheck commands to determine the order in which file system checks
are done at reboot time. For the root file system, specify 1 in the pass
field. For other UFS file systems specify 2 or higher in the pass number
field.
For AdvFS filesets, the sixth field is a pass number field that allows the
quotacheck command to perform all of the consistency checks needed for the
fileset. For the root file system, specify 1 n the pass field. For other
AdvFS file systems specify 2 or higher in the pass number field.
File systems that are on the same disk or domain are checked sequentially,
but file systems on different disks or domains but with the same greater
than 1 pass number are checked at the same time to utilize parallelism
available in the hardware. When all the file systems in a pass have
completed their checks, then the file systems with the numerically next
higher pass number will be processed.
The UFS per disk drive logic is based on the /dev/disk/dsk0a syntax where
different partition letters are treated as being on the same disk drive.
Partitions layered on top of an LSM device may not follow this naming
convention. In this case unique pass numbers may be used to sequence fsck
and quotacheck processing.
If the sixth field is not present or zero, a value of zero is returned and
the fsck command assumes that the file system does not need to be checked.
The following information is from the /usr/include/fstab.h file:
struct fstab {
char *fs_spec; /* block special device name */
char *fs_file; /* file system path prefix */
char *fs_vfstype; /* type of file system */
char *fs_mntops; /* comma separated mount options */
char *fs_type; /* rw, ro, or xx */
int fs_freq; /* dump frequency, in days */
int fs_passno; /* pass number on parallel dump */
};
You can read records from the /etc/fstab file by using the getfsent(),
getfsspec(), getfstype(), and getfsfile() routines.
SEE ALSO
Files: /usr/include/fstab.h
Commands: advfs(4), getfsent(3), fsck(8), mount(8) quataon(8), quotaoff(8)
fsck(8), umount(8)
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Alphabetical
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