View Source: fstab(5) - Waikato Linux Users Group

Edit PageHistory Diff Info LikePages
!!NAME
fstab - static information about the filesystems
!!SYNOPSIS
 __#include <fstab.h>__
!!DESCRIPTION
The file __fstab__ contains descriptive information about the various file systems. __fstab__ is only read by programs, and not written; it is the duty of the system administrator to properly 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 __fstab__ is important because fsck(8), mount(8), and umount(8) sequentially iterate through __fstab__ doing their thing.

The first field, (''fs_spec''), describes the block special device or remote filesystem to be mounted.

For ordinary mounts it will hold (a link to) a block special device node (as created by mknod(8)) for the device to be mounted, like `/dev/cdrom' or `/dev/sdb7'. For NFS mounts one will have <host>:<dir>, e.g., `knuth.aeb.nl:/'.  For procfs, use `proc'.

Instead of giving the device explicitly, one may indicate the (ext2 or xfs) filesystem that is to be mounted by its UUID or volume label (cf. e2label(8) or xfs_admin(8)), writing LABEL=<label>  or  UUID=<uuid>, e.g.,   `LABEL=Boot'   or  `UUID=3e6be9de-8139-11d1-9106-a43f08d823a6'.        This will make the system more robust: adding or removing a  SCSI  disk        changes the disk device name but not the filesystem volume label.

The second field, (''fs_file''), describes the mount point for the filesystem. For swap partitions, this field should be specified as `none'. If the name of the mount point contains spaces these can be escaped as `040'.

The third field, (''fs_vfstype''), describes the type of the filesystem. The system currently supports these types of filesystems (and possibly others - consult ''/proc/filesystems''):

;''minix'': a local filesystem, supporting filenames of length 14 or 30 characters.
;''ext'': a local filesystem with longer filenames and larger inodes. This filesystem has been replaced by the ''ext2'' file system, and should no longer be used.
;''ext2'': a local filesystem with longer filenames, larger inodes, and lots of other features.
;''xiafs'': a local filesystem with longer filenames, larger inodes, and lots of other features.
;''xfs'': a local filesystem with journaling, scalability and lots of other features.
;''msdos'': a local filesystem for MS-DOS partitions.
;''hpfs'': a local filesystem for HPFS partitions.
;''iso9660'': a local filesystem used for CD-ROM drives.
;''nfs'': a filesystem for mounting partitions from remote systems.
;''swap'': a disk partition to be used for swapping.

If ''fs_vfstype'' is specified as ``ignore'' the entry is ignored. This is useful to show disk partitions which are currently unused.

The fourth field, (''fs_mntops''), describes the mount options associated with the filesystem.

It is formatted as a comma separated list of options. It contains at least the type of mount plus any additional options appropriate to the filesystem type. For documentation on the available options for non-nfs file systems, see mount(8). For documentation on all nfs-specific options have a look at nfs(5). Common for all types of file system are the options ``noauto'' (do not mount when mount(8).

The fifth field, (''fs_freq''), is used for these filesystems by the dump(8)[1] command to determine which filesystems need to be dumped. If the fifth field is not present, a value of zero is returned and __dump__ will assume that the filesystem does not need to be dumped.

The sixth field, (''fs_passno''), is used by the fsck(8) 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.

The proper way to read records from __fstab__ is to use the routines getmntent(3).

!!FILES
;''/etc/fstab'': The file __fstab__ resides in ''/etc''.

!!BUGS
The documentation in mount(8) is often more up-to-date.

!!SEE ALSO
getmntent(3), mount(8), swapon(8), fs(5) nfs(5)
!!HISTORY
The __fstab__ file format appeared in 4.0BSD.

[1]: the use of dump(8) is discouraged under Linux, since there is no way for it to get a consistant view of the file system.
15 pages link to fstab(5):
This page is a man page (or other imported legacy content). We are unable to automatically determine the license status of this page.
Last edited on Friday, August 15, 2003 11:11:21 am by JohnMcPherson
Edit PageHistory Diff Info LikePages