fstab(4) — File Formats
OSF — Environment_Note_Added
NAME
fstab − Static information about filesystems
SYNOPSIS
/etc/fstab
#include <fstab.h>
DESCRIPTION
The /etc/fstab file contains descriptive information about the known file systems. /etc/fstab is only read by programs and not written; by convention, you 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 /etc/fstab is important because fsck, mount, and umount sequentially iterate through /etc/fstab during their work.
The first field, (fs_spec), describes the block special device or remote filesystem to be mounted. For filesystems of type ufs, 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 the letter r after the last / (slash) in the special file name.
The second field, (fs_file), describes the mount point for the filesystem. For swap partitions, this field should be specified as none.
The third field, (fs_vfstype), describes the type of the filesystem. The system currently supports four types of filesystems:
ufsa local UNIX filesystem
nfsa Network File System
swapa disk partition to be used for swapping
s5fsa System V file system
The fourth field, (fs_mntops), describes the mount options associated with the filesystem. It is formatted as a comma separated list of options and contains at least the type of mount (see fs_type below) plus any additional options appropriate to the filesystem type.
If the options userquota and/or groupquota are specified, the filesystem is automatically processed by the quotacheck command, and disk quotas are enabled with the quotaon command. By default, filesystem quotas are maintained in files named quota.user and quota.group which are located at the root of the associated filesystem. These defaults may be overridden by putting an equal sign and an alternative absolute pathname following the quota option. Thus, if the user quota file for /tmp is stored in /var/quotas/tmp.user this location can be specified as:
userquota=/var/quotas/tmp.user
The type of the mount is extracted from the fs_mntops field and stored separately in the fs_type field. It is not deleted from the fs_mntops field. If fs_type is rw or ro then the filesystem whose name is given in the fs_file field is normally mounted read-write or read-only on the specified special file. If fs_type is sw then the special file is made available as a piece of swap space by the swapon command at the end of the system reboot procedure. The fields other than fs_spec and fs_type are unused. If fs_type is specified as xx the entry is ignored. This is useful to show disk partitions which are currently unused.
The fifth field, (fs_freq), is used for these filesystems by the dump command to determine which filesystems need to be dumped. If the fifth field is not present, a value of zero is returned and dump assumes that the filesystem does not need to be dumped.
The sixth field, (fs_passno), is used by the fsck program to determine the order in which filesystem checks are done at reboot time. The root filesystem should be specified with a fs_passno of 1, and other filesystems should have a fs_passno 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 will assume that the filesystem does not need to be checked.
#defineFSTAB_RW"rw"/∗ read-write device ∗/
#defineFSTAB_RO"ro"/∗ read-only device ∗/
#defineFSTAB_SW"sw"/∗ swap device ∗/
#defineFSTAB_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 ∗/
intfs_freq;/∗ dump frequency, in days ∗/
intfs_passno;/∗ pass number on parallel dump ∗/
};
The proper way to read records from /etc/fstab is to use the routines getfsent(), getfsspec(), getfstype(), and getfsfile().
ENVIRONMENT NOTES
This section describes system features that are not generic to OSF/1 but that are provided in this OSF/1 implementation.
ULTRIX Compatibility
Description
The third field, (fs_vfstype), describes the type of the filesystem. The system supports an additional type of filesystem:
cdfsan ISO 9660 or High Sierra Formatted (CD−ROM) filesystem
EXAMPLES
The following is an example of an /etc/fstab file:
/dev/rz2a / ufs rw 1 1
/dev/rz0g /usr ufs rw 1 2
/dev/rz2b swap1 ufs sw 0 2
/dev/rz0b swap2 ufs sw 0 2
/dev/rz2g /var ufs rw 1 2
/dev/rz3c /usr/users ufs rw 1 2
/usr/share/man@rabbit /usr/share/man nfs rw,bg 0 0