SYNOPSIS
mount [-lhV]
mount -a [-fFnrsvw] [-t vfstype] [-O optlist]
mount [-fnrsvw] [-o options [,...]] device | dir
mount [-fnrsvw] [-t vfstype] [-o options] device dir
DESCRIPTION
All files accessible in a Unix system are arranged in one
big tree, the file hierarchy, rooted at /. These files
can be spread out over several devices. The mount command
serves to attach the file system found on some device to
the big file tree. Conversely, the umount(8) command will
detach it again.
The standard form of the mount command, is
mount -t type device dir
This tells the kernel to attach the file system found on
device (which is of type type) at the directory dir. The
previous contents (if any) and owner and mode of dir
become invisible, and as long as this file system remains
mounted, the pathname dir refers to the root of the file
system on device.
Three forms of invocation do not actually mount anything:
mount -h
prints a help message;
mount -V
prints a version string; and just
mount [-l] [-t type]
lists all mounted file systems (of type type). The option
-l adds the (ext2, ext3 and XFS) labels in this listing.
See below.
Since Linux 2.4.0 it is possible to remount part of the
file hierarchy somewhere else. The call is
mount --bind olddir newdir
After this call the same contents is accessible in two
places.
This call attaches only (part of) a single filesystem, not
possible submounts. The entire file hierarchy including
submounts is attached a second place using
mount --rbind olddir newdir
Since Linux 2.5.1 it is possible to atomically move a sub
tree to another place. The call is
mount --move olddir newdir
The proc file system is not associated with a special
device, and when mounting it, an arbitrary keyword, such
as proc can be used instead of a device specification.
(i) The command
mount -a [-t type] [-O optlist]
(usually given in a bootscript) causes all file systems
mentioned in fstab (of the proper type and/or having or
not having the proper options) to be mounted as indicated,
except for those whose line contains the noauto keyword.
Adding the -F option will make mount fork, so that the
filesystems are mounted simultaneously.
(ii) When mounting a file system mentioned in fstab, it
suffices to give only the device, or only the mount point.
(iii) Normally, only the superuser can mount file systems.
However, when fstab contains the user option on a line,
then anybody can mount the corresponding system.
Thus, given a line
/dev/cdrom /cd iso9660 ro,user,noauto,unhide
any user can mount the iso9660 file system found on his
CDROM using the command
mount /dev/cdrom
or
mount /cd
For more details, see fstab(5). Only the user that
mounted a filesystem can unmount it again. If any user
should be able to unmount, then use users instead of user
in the fstab line. The owner option is similar to the
user option, with the restriction that the user must be
the owner of the special file. This may be useful e.g. for
/dev/fd if a login script makes the console user owner of
this device.
The programs mount and umount maintain a list of currently
mounted file systems in the file /etc/mtab. If no argu
ments are given to mount, this list is printed.
When the proc filesystem is mounted (say at /proc), the
files /etc/mtab and /proc/mounts have very similar con
tents. The former has somewhat more information, such as
the mount options used, but is not necessarily up-to-date
(cf. the -n option below). It is possible to replace
/etc/mtab by a symbolic link to /proc/mounts, but some
information is lost that way, and in particular working
with the loop device will be less convenient, and using
the "user" option will fail.
OPTIONS
The full set of options used by an invocation of mount is
determined by first extracting the options for the file
system from the fstab table, then applying any options
specified by the -o argument, and finally applying a -r or
incarnation of mount for each device. This will do
the mounts on different devices or different NFS
servers in parallel. This has the advantage that
it is faster; also NFS timeouts go in parallel. A
disadvantage is that the mounts are done in unde
fined order. Thus, you cannot use this option if
you want to mount both /usr and /usr/spool.
-f Causes everything to be done except for the actual
system call; if it's not obvious, this ``fakes''
mounting the file system. This option is useful in
conjunction with the -v flag to determine what the
mount command is trying to do. It can also be used
to add entries for devices that were mounted ear
lier with the -n option.
-i Don't call the /sbin/mount.<filesystem> helper even
if it exists.
-l Add the ext2, ext3 and XFS labels in the mount out
put. Mount must have permission to read the disk
device (e.g. be suid root) for this to work. One
can set such a label for ext2 or ext3 using the
e2label(8) utility, or for XFS using xfs_admin(8).
-n Mount without writing in /etc/mtab. This is neces
sary for example when /etc is on a read-only file
system.
-s Tolerate sloppy mount options rather than failing.
This will ignore mount options not supported by a
filesystem type. Not all filesystems support this
option. This option exists for support of the Linux
autofs-based automounter.
-r Mount the file system read-only. A synonym is -o
ro.
-w Mount the file system read/write. This is the
default. A synonym is -o rw.
-L label
Mount the partition that has the specified label.
-U uuid
Mount the partition that has the specified uuid.
These two options require the file /proc/partitions
(present since Linux 2.1.116) to exist.
-t vfstype
The argument following the -t is used to indicate
the file system type. The file system types which
required. For a few types however (like nfs,
smbfs, ncpfs) ad hoc code is necessary. The nfs ad
hoc code is built in, but smbfs and ncpfs have a
separate mount program. In order to make it possi
ble to treat all types in a uniform way, mount will
execute the program /sbin/mount.TYPE (if that
exists) when called with type TYPE. Since various
versions of the smbmount program have different
calling conventions, /sbin/mount.smb may have to be
a shell script that sets up the desired call.
The type iso9660 is the default. If no -t option
is given, or if the auto type is specified, the
superblock is probed for the filesystem type (adfs,
bfs, cramfs, ext, ext2, ext3, hfs, hpfs, iso9660,
jfs, minix, ntfs, qnx4, reiserfs, romfs, udf, ufs,
vxfs, xfs, xiafs are supported). If this probe
fails, mount will try to read the file
/etc/filesystems, or, if that does not exist,
/proc/filesystems. All of the filesystem types
listed there will be tried, except for those that
are labeled "nodev" (e.g., devpts, proc and nfs).
If /etc/filesystems ends in a line with a single *
only, mount will read /proc/filesystems afterwards.
The auto type may be useful for user-mounted flop
pies. Creating a file /etc/filesystems can be use
ful to change the probe order (e.g., to try vfat
before msdos) or if you use a kernel module
autoloader. Warning: the probing uses a heuristic
(the presence of appropriate `magic'), and could
recognize the wrong filesystem type, possibly with
catastrophic consequences. If your data is valu
able, don't ask mount to guess.
More than one type may be specified in a comma sep
arated list. The list of file system types can be
prefixed with no to specify the file system types
on which no action should be taken. (This can be
meaningful with the -a option.)
For example, the command:
mount -a -t nomsdos,ext
mounts all file systems except those of type msdos
and ext.
-O Used in conjunction with -a, to limit the set of
filesystems to which the -a is applied. Like -t in
this regard except that it is useless except in the
context of -a. For example, the command:
mount -a -O no_netdev
mounts all file systems except those which have the
-o Options are specified with a -o flag followed by a
comma separated string of options. Some of these
options are only useful when they appear in the
/etc/fstab file. The following options apply to
any file system that is being mounted (but not
every file system actually honors them - e.g., the
sync option today has effect only for ext2, ext3
and ufs):
async All I/O to the file system should be done
asynchronously.
atime Update inode access time for each access.
This is the default.
auto Can be mounted with the -a option.
defaults
Use default options: rw, suid, dev, exec,
auto, nouser, and async.
dev Interpret character or block special devices
on the file system.
exec Permit execution of binaries.
_netdev
The filesystem resides on a device that
requires network access (used to prevent the
system from attempting to mount these
filesystems until the network has been
enabled on the system).
noatime
Do not update inode access times on this
file system (e.g, for faster access on the
news spool to speed up news servers).
noauto Can only be mounted explicitly (i.e., the -a
option will not cause the file system to be
mounted).
nodev Do not interpret character or block special
devices on the file system.
noexec Do not allow execution of any binaries on
the mounted file system. This option might
be useful for a server that has file systems
containing binaries for architectures other
than its own.
nosuid Do not allow set-user-identifier or set-
ro Mount the file system read-only.
rw Mount the file system read-write.
suid Allow set-user-identifier or set-group-iden
tifier bits to take effect.
sync All I/O to the file system should be done
synchronously.
dirsync
All directory updates within the file system
should be done synchronously. This affects
the following system calls: creat, link,
unlink, symlink, mkdir, rmdir, mknod and
rename.
user Allow an ordinary user to mount the file
system. The name of the mounting user is
written to mtab so that he can unmount the
file system again. This option implies the
options noexec, nosuid, and nodev (unless
overridden by subsequent options, as in the
option line user,exec,dev,suid).
users Allow every user to mount and unmount the
file system. This option implies the
options noexec, nosuid, and nodev (unless
overridden by subsequent options, as in the
option line users,exec,dev,suid).
--bind Remount a subtree somewhere else (so that its con
tents are available in both places). See above.
--move Move a subtree to some other place. See above.
FILESYSTEM SPECIFIC MOUNT OPTIONS
The following options apply only to certain file systems.
We sort them by file system. They all follow the -o flag.
Mount options for adfs
uid=value and gid=value
Set the owner and group of the files in the file
system (default: uid=gid=0).
ownmask=value and othmask=value
Set the permission mask for ADFS 'owner' permis
sions and 'other' permissions, respectively
(default: 0700 and 0077, respectively). See also
/usr/src/linux/Documentation/filesystems/adfs.txt.
The value is given in octal.
protect
Do not allow any changes to the protection bits on
the file system.
usemp Set uid and gid of the root of the file system to
the uid and gid of the mount point upon the first
sync or umount, and then clear this option.
Strange...
verbose
Print an informational message for each successful
mount.
prefix=string
Prefix used before volume name, when following a
link.
volume=string
Prefix (of length at most 30) used before '/' when
following a symbolic link.
reserved=value
(Default: 2.) Number of unused blocks at the start
of the device.
root=value
Give explicitly the location of the root block.
bs=value
Give blocksize. Allowed values are 512, 1024, 2048,
4096.
grpquota / noquota / quota / usrquota
These options are accepted but ignored. (However,
quota utilities may react to such strings in
/etc/fstab.)
Mount options for coherent
None.
Mount options for devpts
The devpts file system is a pseudo file system, tradition
ally mounted on /dev/pts. In order to acquire a pseudo
terminal, a process opens /dev/ptmx; the number of the
pseudo terminal is then made available to the process and
the pseudo terminal slave can be accessed as
/dev/pts/<number>.
Mount options for ext
None. Note that the `ext' file system is obsolete. Don't
use it. Since Linux version 2.1.21 extfs is no longer
part of the kernel source.
Mount options for ext2
The `ext2' file system is the standard Linux file system.
Due to a kernel bug, it may be mounted with random mount
options (fixed in Linux 2.0.4).
bsddf / minixdf
Set the behaviour for the statfs system call. The
minixdf behaviour is to return in the f_blocks
field the total number of blocks of the file sys
tem, while the bsddf behaviour (which is the
default) is to subtract the overhead blocks used by
the ext2 file system and not available for file
storage. Thus
% mount /k -o minixdf; df /k; umount /k
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/sda6 2630655 86954 2412169 3% /k
% mount /k -o bsddf; df /k; umount /k
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/sda6 2543714 13 2412169 0% /k
(Note that this example shows that one can add command
line options to the options given in /etc/fstab.)
check / check=normal / check=strict
Set checking level. When at least one of these
options is set (and check=normal is set by default)
the inodes and blocks bitmaps are checked upon
mount (which can take half a minute or so on a big
disk, and is rather useless). With strict check
ing, block deallocation checks that the block to
free is in the data zone.
check=none / nocheck
No checking is done. This is fast. Recent kernels
do not have a check option anymore - checking with
e2fsck(8) is more meaningful.
debug Print debugging info upon each (re)mount.
errors=continue / errors=remount-ro / errors=panic
Define the behaviour when an error is encountered.
(Either ignore errors and just mark the file system
erroneous and continue, or remount the file system
resgid=n and resuid=n
The ext2 file system reserves a certain percentage
of the available space (by default 5%, see
mke2fs(8) and tune2fs(8)). These options determine
who can use the reserved blocks. (Roughly: whoever
has the specified uid, or belongs to the specified
group.)
sb=n Instead of block 1, use block n as superblock. This
could be useful when the filesystem has been dam
aged. (Earlier, copies of the superblock would be
made every 8192 blocks: in block 1, 8193, 16385,
... (and one got hundreds or even thousands of
copies on a big filesystem). Since version 1.08,
mke2fs has a -s (sparse superblock) option to
reduce the number of backup superblocks, and since
version 1.15 this is the default. Note that this
may mean that ext2 filesystems created by a recent
mke2fs cannot be mounted r/w under Linux 2.0.*.)
The block number here uses 1k units. Thus, if you
want to use logical block 32768 on a filesystem
with 4k blocks, use "sb=131072".
grpquota / noquota / quota / usrquota
These options are accepted but ignored.
nouid32
Disables 32-bit UIDs and GIDs. This is for inter
operability with older kernels which only store and
expect 16-bit values.
user_xattr
Enable Extended User Attributes. See the attr(5)
manual page.
acl Enable POSIX Access Control Lists. See the acl(5)
manual page.
Mount options for ext3
The `ext3' file system is version of the ext2 file system
which has been enhanced with journalling. It supports the
same options as ext2 as well as the following additions:
journal=update
Update the ext3 file system's journal to the cur
rent format.
journal=inum
When a journal already exists, this option is
ignored. Otherwise, it specifies the number of the
to being written into the main file system.
ordered
This is the default mode. All data is
forced directly out to the main file system
prior to its metadata being committed to the
journal.
writeback
Data ordering is not preserved - data may be
written into the main file system after its
metadata has been committed to the journal.
This is rumoured to be the highest-through
put option. It guarantees internal file
system integrity, however it can allow old
data to appear in files after a crash and
journal recovery.
user_xattr
Enable Extended User Attributes. See the
attr(5) manual page.
acl Enable POSIX Access Control Lists. See the
acl(5) manual page.
Mount options for fat
(Note: fat is not a separate filesystem, but a common part
of the msdos, umsdos and vfat filesystems.)
blocksize=512 / blocksize=1024 / blocksize=2048
Set blocksize (default 512).
uid=value and gid=value
Set the owner and group of all files. (Default: the
uid and gid of the current process.)
umask=value
Set the umask (the bitmask of the permissions that
are not present). The default is the umask of the
current process. The value is given in octal.
dmask=value
Set the umask applied to directories only. The
default is the umask of the current process. The
value is given in octal. Present since 2.5.43.
fmask=value
Set the umask applied to regular files only. The
default is the umask of the current process. The
value is given in octal. Present since 2.5.43.
s[trict]
Like "normal", but names may not contain
long parts and special characters that are
sometimes used on Linux, but are not
accepted by MS-DOS are rejected. (+, =,
spaces, etc.)
codepage=value
Sets the codepage for converting to shortname char
acters on FAT and VFAT filesystems. By default,
codepage 437 is used.
conv=b[inary] / conv=t[ext] / conv=a[uto]
The fat file system can perform CRLF<-->NL (MS-DOS
text format to UNIX text format) conversion in the
kernel. The following conversion modes are avail
able:
binary no translation is performed. This is the
default.
text CRLF<-->NL translation is performed on all
files.
auto CRLF<-->NL translation is performed on all
files that don't have a "well-known binary"
extension. The list of known extensions can
be found at the beginning of fs/fat/misc.c
(as of 2.0, the list is: exe, com, bin, app,
sys, drv, ovl, ovr, obj, lib, dll, pif, arc,
zip, lha, lzh, zoo, tar, z, arj, tz, taz,
tzp, tpz, gz, tgz, deb, gif, bmp, tif, gl,
jpg, pcx, tfm, vf, gf, pk, pxl, dvi).
Programs that do computed lseeks won't like in-ker
nel text conversion. Several people have had their
data ruined by this translation. Beware!
For file systems mounted in binary mode, a conver
sion tool (fromdos/todos) is available.
cvf_format=module
Forces the driver to use the CVF (Compressed Volume
File) module cvf_module instead of auto-detection.
If the kernel supports kmod, the cvf_format=xxx
option also controls on-demand CVF module loading.
cvf_option=option
Option passed to the CVF module.
debug Turn on the debug flag. A version string and a
quiet Turn on the quiet flag. Attempts to chown or chmod
files do not return errors, although they fail. Use
with caution!
sys_immutable, showexec, dots, nodots, dotsOK=[yes|no]
Various misguided attempts to force Unix or DOS
conventions onto a FAT file system.
Mount options for hpfs
uid=value and gid=value
Set the owner and group of all files. (Default: the
uid and gid of the current process.)
umask=value
Set the umask (the bitmask of the permissions that
are not present). The default is the umask of the
current process. The value is given in octal.
case=lower / case=asis
Convert all files names to lower case, or leave
them. (Default: case=lower.)
conv=binary / conv=text / conv=auto
For conv=text, delete some random CRs (in particu
lar, all followed by NL) when reading a file. For
conv=auto, choose more or less at random between
conv=binary and conv=text. For conv=binary, just
read what is in the file. This is the default.
nocheck
Do not abort mounting when certain consistency
checks fail.
Mount options for iso9660
ISO 9660 is a standard describing a filesystem structure
to be used on CD-ROMs. (This filesystem type is also seen
on some DVDs. See also the udf filesystem.)
Normal iso9660 filenames appear in a 8.3 format (i.e.,
DOS-like restrictions on filename length), and in addition
all characters are in upper case. Also there is no field
for file ownership, protection, number of links, provision
for block/character devices, etc.
Rock Ridge is an extension to iso9660 that provides all of
these unix like features. Basically there are extensions
to each directory record that supply all of the additional
information, and when Rock Ridge is in use, the filesystem
is indistinguishable from a normal UNIX file system
uid=value and gid=value
Give all files in the file system the indicated
user or group id, possibly overriding the informa
tion found in the Rock Ridge extensions. (Default:
uid=0,gid=0.)
map=n[ormal] / map=o[ff] / map=a[corn]
For non-Rock Ridge volumes, normal name translation
maps upper to lower case ASCII, drops a trailing
`;1', and converts `;' to `.'. With map=off no
name translation is done. See norock. (Default:
map=normal.) map=acorn is like map=normal but also
apply Acorn extensions if present.
mode=value
For non-Rock Ridge volumes, give all files the
indicated mode. (Default: read permission for
everybody.) Since Linux 2.1.37 one no longer needs
to specify the mode in decimal. (Octal is indicated
by a leading 0.)
unhide Also show hidden and associated files.
block=[512|1024|2048]
Set the block size to the indicated value.
(Default: block=1024.)
conv=a[uto] / conv=b[inary] / conv=m[text] / conv=t[ext]
(Default: conv=binary.) Since Linux 1.3.54 this
option has no effect anymore. (And non-binary set
tings used to be very dangerous, possibly leading
to silent data corruption.)
cruft If the high byte of the file length contains other
garbage, set this mount option to ignore the high
order bits of the file length. This implies that a
file cannot be larger than 16MB. The `cruft'
option is set automatically if the entire CDROM has
a weird size (negative, or more than 800MB). It is
also set when volume sequence numbers other than 0
or 1 are seen.
session=x
Select number of session on multisession CD. (Since
2.3.4.)
sbsector=xxx
Session begins from sector xxx. (Since 2.3.4.)
The following options are the same as for vfat and speci
fying them only makes sense when using discs encoded using
iocharset=name
Character set to use for converting from Unicode to
ASCII. Joliet filenames are stored in Unicode for
mat, but Unix for the most part doesn't know how to
deal with Unicode. There is also an option of
doing UTF8 translations with the utf8 option.
utf8 Encode Unicode names in UTF8 format. Default is no.
Mount options for minix
None.
Mount options for msdos
See mount options for fat. If the msdos file system
detects an inconsistency, it reports an error and sets the
file system read-only. The file system can be made write
able again by remounting it.
Mount options for ncp
Just like nfs, the ncp implementation expects a binary
argument (a struct ncp_mount_data) to the mount system
call. This argument is constructed by ncpmount(8) and the
current version of mount (2.6h) does not know anything
about ncp.
Mount options for nfs
Instead of a textual option string, parsed by the kernel,
the nfs file system expects a binary argument of type
struct nfs_mount_data. The program mount itself parses
the following options of the form `tag=value', and puts
them in the structure mentioned: rsize=n, wsize=n,
timeo=n, retrans=n, acregmin=n, acregmax=n, acdirmin=n,
acdirmax=n, actimeo=n, retry=n, port=n, mountport=n, moun
thost=name, mountprog=n, mountvers=n, nfsprog=n,
nfsvers=n, namlen=n. The option addr=n is accepted but
ignored. Also the following Boolean options, possibly
preceded by no are recognized: bg, fg, soft, hard, intr,
posix, cto, ac, tcp, udp, lock, acl. For details, see
nfs(5).
Especially useful options include
rsize=8192,wsize=8192
This will make your nfs connection faster than with
the default buffer size of 4096. (NFSv2 does not
work with larger values of rsize and wsize.)
nolock Do not use locking. Do not start lockd.
Mount options for ntfs
iocharset=name
Character set to use when returning file names.
Unlike VFAT, NTFS suppresses names that contain
unconvertible characters.
utf8 Use UTF-8 for converting file names.
uni_xlate=[0|1|2]
For 0 (or `no' or `false'), do not use escape
sequences for unknown Unicode characters. For 1
(or `yes' or `true') or 2, use vfat-style 4-byte
escape sequences starting with ":". Here 2 give a
little-endian encoding and 1 a byteswapped bigen
dian encoding.
posix=[0|1]
If enabled (posix=1), the file system distinguishes
between upper and lower case. The 8.3 alias names
are presented as hard links instead of being sup
pressed.
uid=value, gid=value and umask=value
Set the file permission on the filesystem. The
umask value is given in octal. By default, the
files are owned by root and not readable by some
body else.
Mount options for proc
uid=value and gid=value
These options are recognized, but have no effect as
far as I can see.
Mount options for ramfs
Ramfs is a memory based filesystem. Mount it and you have
it. Unmount it and it is gone. Present since Linux
2.3.99pre4. There are no mount options.
Mount options for reiserfs
Reiserfs is a journaling filesystem. The reiserfs mount
options are more fully described at
http://www.namesys.com/mount-options.html.
conv Instructs version 3.6 reiserfs software to mount a
version 3.5 file system, using the 3.6 format for
tea A Davis-Meyer function implemented by Jeremy
Fitzhardinge. It uses hash permuting bits
in the name. It gets high randomness and,
therefore, low probability of hash colli
sions at come CPU cost. This may be used if
EHASHCOLLISION errors are experienced with
the r5 hash.
r5 A modified version of the rupasov hash. It
is used by default and is the best choice
unless the file system has huge directories
and unusual file-name patterns.
detect Instructs mount to detect which hash func
tion is in use by examining the file system
being mounted, and to write this informa
tion into the reiserfs superblock. This is
only useful on the first mount of an old
format file system.
hashed_relocation
Tunes the block allocator. This may provide perfor
mance improvements in some situations.
no_unhashed_relocation
Tunes the block allocator. This may provide perfor
mance improvements in some situations.
noborder
Disable the border allocator algorithm invented by
Yury Yu. Rupasov. This may provide performance
improvements in some situations.
nolog Disable journalling. This will provide slight per
formance improvements in some situations at the
cost of losing reiserfs's fast recovery from
crashes. Even with this option turned on, reiserfs
still performs all journalling operations, save for
actual writes into its journalling area. Implemen
tation of nolog is a work in progress.
notail By default, reiserfs stores small files and `file
tails' directly into its tree. This confuses some
utilities such as LILO(8). This option is used to
disable packing of files into the tree.
replayonly
Replay the transactions which are in the journal,
but do not actually mount the file system. Mainly
used by reiserfsck.
manual page.
Mount options for romfs
None.
Mount options for smbfs
Just like nfs, the smb implementation expects a binary
argument (a struct smb_mount_data) to the mount system
call. This argument is constructed by smbmount(8) and the
current version of mount (2.9w) does not know anything
about smb.
Mount options for sysv
None.
Mount options for tmpfs
The following parameters accept a suffix k, m or g for Ki,
Mi, Gi (binary kilo, mega and giga) and can be changed on
remount.
size=nbytes
Override default size of the filesystem. The size
is given in bytes, and rounded down to entire
pages. The default is half of the memory.
nr_blocks=
Set number of blocks.
nr_inodes=
Set number of inodes.
mode= Set initial permissions of the root directory.
Mount options for udf
udf is the "Universal Disk Format" filesystem defined by
the Optical Storage Technology Association, and is often
used for DVD-ROM. See also iso9660.
gid= Set the default group.
umask= Set the default umask. The value is given in
octal.
uid= Set the default user.
unhide Show otherwise hidden files.
session=
Set the CDROM session counting from 0. Default:
last session.
anchor=
Override standard anchor location. Default: 256.
volume=
Override the VolumeDesc location. (unused)
partition=
Override the PartitionDesc location. (unused)
lastblock=
Set the last block of the filesystem.
fileset=
Override the fileset block location. (unused)
rootdir=
Override the root directory location. (unused)
Mount options for ufs
ufstype=value
UFS is a file system widely used in different oper
ating systems. The problem are differences among
implementations. Features of some implementations
are undocumented, so its hard to recognize the type
of ufs automatically. That's why the user must
specify the type of ufs by mount option. Possible
values are:
old Old format of ufs, this is the default, read
only. (Don't forget to give the -r option.)
44bsd For filesystems created by a BSD-like system
(NetBSD,FreeBSD,OpenBSD).
sun For filesystems created by SunOS or Solaris
on Sparc.
sunx86 For filesystems created by Solaris on x86.
nextstep
For filesystems created by NeXTStep (on NeXT
station) (currently read only).
nextstep-cd
For NextStep CDROMs (block_size == 2048),
read-only.
present; when an error is encountered only a
console message is printed.
Mount options for umsdos
See mount options for msdos. The dotsOK option is explic
itly killed by umsdos.
Mount options for vfat
First of all, the mount options for fat are recognized.
The dotsOK option is explicitly killed by vfat. Further
more, there are
uni_xlate
Translate unhandled Unicode characters to special
escaped sequences. This lets you backup and
restore filenames that are created with any Unicode
characters. Without this option, a '?' is used when
no translation is possible. The escape character is
':' because it is otherwise illegal on the vfat
filesystem. The escape sequence that gets used,
where u is the unicode character, is: ':', (u &
0x3f), ((u>>6) & 0x3f), (u>>12).
posix Allow two files with names that only differ in
case.
nonumtail
First try to make a short name without sequence
number, before trying name~num.ext.
utf8 UTF8 is the filesystem safe 8-bit encoding of Uni
code that is used by the console. It can be be
enabled for the filesystem with this option. If
`uni_xlate' gets set, UTF8 gets disabled.
shortname=[lower|win95|winnt|mixed]
Defines the behaviour for creation and display of
filenames which fit into 8.3 characters. If a long
name for a file exists, it will always be preferred
display. There are four modes:
lower Force the short name to lower case upon dis
play; store a long name when the short name
is not all upper case.
win95 Force the short name to upper case upon dis
play; store a long name when the short name
is not all upper case.
Mount options for xfs
biosize=size
Sets the preferred buffered I/O size (default size
is 64K). size must be expressed as the logarithm
(base2) of the desired I/O size. Valid values for
this option are 14 through 16, inclusive (i.e. 16K,
32K, and 64K bytes). On machines with a 4K page
size, 13 (8K bytes) is also a valid size. The pre
ferred buffered I/O size can also be altered on an
individual file basis using the ioctl(2) system
call.
dmapi / xdsm
Enable the DMAPI (Data Management API) event call
outs.
logbufs=value
Set the number of in-memory log buffers. Valid
numbers range from 2-8 inclusive. The default
value is 8 buffers for filesystems with a blocksize
of 64K, 4 buffers for filesystems with a blocksize
of 32K, 3 buffers for filesystems with a blocksize
of 16K, and 2 buffers for all other configurations.
Increasing the number of buffers may increase per
formance on some workloads at the cost of the mem
ory used for the additional log buffers and their
associated control structures.
logbsize=value
Set the size of each in-memory log buffer. Valid
sizes are 16384 (16K) and 32768 (32K). The default
value for machines with more than 32MB of memory is
32768, machines with less memory use 16384 by
default.
logdev=device and rtdev=device
Use an external log (metadata journal) and/or real-
time device. An XFS filesystem has up to three
parts: a data section, a log section, and a real-
time section. The real-time section is optional,
and the log section can be separate from the data
section or contained within it. Refer to xfs(5).
noalign
Data allocations will not be aligned at stripe unit
boundaries.
noatime
Access timestamps are not updated when a file is
read.
option is in effect, timestamp updates from O_SYNC
writes can be lost if the system crashes.
quota / usrquota / uqnoenforce
User disk quota accounting enabled, and limits
(optionally) enforced.
grpquota / gqnoenforce
Group disk quota accounting enabled and limits
(optionally) enforced.
sunit=value and swidth=value
Used to specify the stripe unit and width for a
RAID device or a stripe volume. value must be
specified in 512-byte block units. If this option
is not specified and the filesystem was made on a
stripe volume or the stripe width or unit were
specified for the RAID device at mkfs time, then
the mount system call will restore the value from
the superblock. For filesystems that are made
directly on RAID devices, these options can be used
to override the information in the superblock if
the underlying disk layout changes after the
filesystem has been created. The swidth option is
required if the sunit option has been specified,
and must be a multiple of the sunit value.
Mount options for xiafs
None. Although nothing is wrong with xiafs, it is not used
much, and is not maintained. Probably one shouldn't use
it. Since Linux version 2.1.21 xiafs is no longer part of
the kernel source.
THE LOOP DEVICE
One further possible type is a mount via the loop device.
For example, the command
mount /tmp/fdimage /mnt -t msdos -o loop=/dev/loop3,blocksize=1024
will set up the loop device /dev/loop3 to correspond to
the file /tmp/fdimage, and then mount this device on /mnt.
This type of mount knows about three options, namely loop,
offset and encryption, that are really options to los
etup(8). If no explicit loop device is mentioned (but
just an option `-o loop' is given), then mount will try to
find some unused loop device and use that. If you are not
so unwise as to make /etc/mtab a symbolic link to
/proc/mounts then any loop device allocated by mount will
be freed by umount. You can also free a loop device by
hand, using `losetup -d', see losetup(8).
8 user interrupt
16 problems writing or locking /etc/mtab
32 mount failure
64 some mount succeeded
FILES
/etc/fstab file system table
/etc/mtab table of mounted file systems
/etc/mtab~ lock file
/etc/mtab.tmp temporary file
SEE ALSO
mount(2), umount(2), fstab(5), umount(8), swapon(8),
nfs(5), xfs(5), e2label(8), xfs_admin(8), mountd(8),
nfsd(8), mke2fs(8), tune2fs(8), losetup(8)
BUGS
It is possible for a corrupted file system to cause a
crash.
Some Linux file systems don't support -o sync and -o
dirsync (the ext2 and ext3 file systems do support syn
chronous updates (a la BSD) when mounted with the sync
option).
The -o remount may not be able to change mount parameters
(all ext2fs-specific parameters, except sb, are changeable
with a remount, for example, but you can't change gid or
umask for the fatfs).
HISTORY
A mount command existed in Version 5 AT&T UNIX.
Linux 2.0 14 September 1997 MOUNT(8)
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