fstab(4)fstab(4)NAMEfstab - 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 charac‐
ter special file name, the program must create it by inserting the let‐
ter 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 sys‐
tem currently supports the following file systems: Specifies an ISO
9660 or High Sierra Formatted (CD-ROM) file system. Specifies a Uni‐
versal Disk Format (UDF) formatted file system. 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. 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. Specifies a local UNIX file system (Berkeley fast file sys‐
tem). Specifies the memory file system (RAM Disk). (See mfs(8).)
Specifies a local Advanced File System (AdvFS). Specifies the PC File
System. Specifies the DCE Distributed File System. Specifies the DCE
Episode File System. Specifies the File on File Mounting system (used
by streams). Specifies the File Descriptor File System (used by
streams). 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. Speci‐
fies that the file system is mounted with read-only access. Specifies
that the file system is mounted with read-write access. Specifies that
the file system is mounted with read-write access. Specifies that the
file system can be mounted even if it was not cleanly unmounted. This
is only for UFS. 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 quo‐
tas 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 speci‐
fied by the mount point. For example, the quotas for the file
system on which /usr is mounted are located in the /usr direc‐
tory. 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 sys‐
tems. 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 sys‐
tem 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 sequen‐
tially, 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 numer‐
ically 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), quo‐
taoff(8)fsck(8), umount(8)fstab(4)
