table of contents
FSTAB(5) | File Formats | FSTAB(5) |
NAME¶
fstab - static information about the filesystemsSYNOPSIS¶
/etc/fstabDESCRIPTION¶
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. Lines starting with '#' are comments, blank lines are ignored. 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).This field 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 filesystem that is
to be mounted by its UUID or 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'.
It's also possible to use PARTUUID= and PARTLABEL=. These partitions identifiers
are supported for example for GUID Partition Table (GPT).
See mount(8), blkid(8) or lsblk(8) for more details about
devices identifiers.
Note that mount(8) uses UUIDs as strings. The string representation of
the UUID should be based on lower case characters.
The second field (fs_file).
This field 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).
This field describes the type of the filesystem. Linux
supports lots of filesystem types, such as adfs, affs,
autofs, coda, coherent, cramfs, devpts,
efs, ext2, ext3, hfs, hpfs, iso9660,
jfs, minix, msdos, ncpfs, nfs, ntfs,
proc, qnx4, reiserfs, romfs, smbfs,
sysv, tmpfs, udf, ufs, umsdos, vfat,
xenix, xfs, and possibly others. For more details, see
mount(8).
For the filesystems currently supported by the running kernel, see
/proc/filesystems.
An entry swap denotes a file or partition to be used for swapping, cf.
swapon(8). An entry none is useful for bind or move mounts.
mount(8) and umount(8) support filesystem subtypes. The
subtype is defined by '.subtype' suffix. For example 'fuse.sshfs'. It's
recommended to use subtype notation rather than add any prefix to the first
fstab field (for example 'sshfs#example.com' is deprecated).
The fourth field (fs_mntops).
This field 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 mount options, see mount(8). For
documentation on the available swap options, see swapon(8).
Basic file system independent options are:
The fifth field (fs_freq).
- defaults
- use default options: rw, suid, dev, exec, auto, nouser, and async.
- noauto
- do not mount when "mount -a" is given (e.g., at boot time)
- user
- allow a user to mount
- owner
- allow device owner to mount
- comment
- or x-<name> for use by fstab-maintaining programs
- nofail
- do not report errors for this device if it does not exist.
This field is used for these filesystems by the
dump(8) 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).
This field 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.
NOTES¶
The proper way to read records from fstab is to use the routines getmntent(3) or libmount. The keyword ignore as filesystem type (3rd field) is not more supported by the pure libmount based mount utility (since util-linux v2.22).FILES¶
/etc/fstab, <fstab.h>SEE ALSO¶
findmnt(8), mount(8), swapon(8), fs(5), getmntent(3)HISTORY¶
The ancestor of this fstab file format appeared in 4.0BSD.AVAILABILITY¶
This man page is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.August 2010 | util-linux |