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MOUNT
!!!MOUNT
NAME
SYNOPSIS
DESCRIPTION
OPTIONS
FILESYSTEM SPECIFIC MOUNT OPTIONS
Mount options for adfs
Mount options for affs
Mount options for coherent
Mount options for devpts
Mount options for ext
Mount options for ext2
Mount options for ext3
Mount options for fat
Mount options for hpfs
Mount options for iso9660
Mount options for minix
Mount options for msdos
Mount options for ncp
Mount options for nfs
Mount options for ntfs
Mount options for proc
Mount options for reiserfs
Mount options for romfs
Mount options for smbfs
Mount options for sysv
Mount options for tmpfs
Mount options for udf
Mount options for ufs
Mount options for umsdos
Mount options for vfat
Mount options for xenix
Mount options for xfs
Mount options for xiafs
THE LOOP DEVICE
FILES
SEE ALSO
BUGS
HISTORY
----
!!NAME


mount - mount a file system
!!SYNOPSIS


__mount [[-lhV]__


__mount -a [[-fFnrsvw] [[-t__ ''vfstype''__]
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__


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.
(The customary choice ''none'' is less fortunate: the
error message `none busy' from __umount__ can be
confusing.)


Most devices are indicated by a file name (of a block
special device), like ''/dev/sda1'', but there are other
possibilities. For example, in the case of an NFS mount,
''device'' may look like ''knuth.cwi.nl:/dir''. It is
possible to indicate a block special device using its volume
label or UUID (see the -L and -U options
below).


The file ''/etc/fstab'' (see fstab(5)), may
contain lines describing what devices are usually mounted
where, using which options. This file is used in three
ways:


(i) The command


__mount -a [[-t__ ''type''__]__


(usually given in a bootscript) causes all file systems
mentioned in ''fstab'' (of the proper type) 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 arguments 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 contents. 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.
!!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 __-w__ option, when
present.


Options available for the __mount__ command:


__-V__


Output version.


__-h__


Print a help message.


__-v__


Verbose mode.


__-p__ ''num''


If the mount requires a passphrase to be entered, read it
from file descriptor ''num'' instead of from the
terminal.


__-a__


Mount all filesystems (of the given types) mentioned in
''fstab''.


__-F__


(Used in conjunction with __-a__.) Fork off a new
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 undefined 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 earlier with the -n option.


__-l__


Add the ext2, ext3 and XFS labels in the mount output. 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 necessary
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 are currently
supported are: ''adfs'', ''affs'', ''autofs'',
''coda'', ''coherent'', ''cramfs'', ''devpts'',
''efs'', ''ext'', ''ext2'', ''ext3'',
''hfs'', ''hpfs'', ''iso9660'', ''jfs'',
''minix'', ''msdos'', ''ncpfs'', ''nfs'',
''ntfs'', ''proc'', ''qnx4'', ''reiserfs'',
''romfs'', ''smbfs'', ''sysv'', ''tmpfs'',
''udf'', ''ufs'', ''umsdos'', ''vfat'',
''xenix'', ''xfs'', ''xiafs''. Note that coherent,
sysv and xenix are equivalent and that ''xenix'' and
''coherent'' will be removed at some point in the future
-- use ''sysv'' instead. Since kernel version 2.1.21 the
types ''ext'' and ''xiafs'' do not exist
anymore.


For most types all the __mount__ program has to do is
issue a simple mount(2) system call, and no detailed
knowledge of the filesystem type is 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
possible 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'', ''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
''devpts'', ''proc'' and
''nfs'').


Note that the __auto__ type may be useful for
user-mounted floppies. Creating a file
''/etc/filesystems'' can be useful 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.


More than one type may be specified in a comma separated
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__


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.


__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-group-identifier
bits to take effect. (This seems safe, but is in fact rather
unsafe if you have suidperl(1) installed.)


__nouser__


Forbid an ordinary (i.e., non-root) user to mount the file
system. This is the default.


__remount__


Attempt to remount an already-mounted file system. This is
commonly used to change the mount flags for a file system,
especially to make a readonly file system writeable. It does
not change device or mount point.


__ro__


Mount the file system read-only.


__rw__


Mount the file system read-write.


__suid__


Allow set-user-identifier or set-group-identifier bits to
take effect.


__sync__


All I/O to the file system should be done
synchronously.


__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__).


__encryption__


Specifies an encryption algorithm to use. Used in
conjunction with the __loop__ option.


__keybits__


Specifies the key size to use for an encryption algorithm.
Used in conjunction with the __loop__ and
__encryption__ options.
!!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' permissions and
'other' permissions, respectively (default: 0700 and 0077,
respectively). See also
''/usr/src/linux/Documentation/filesystems/adfs.txt''.
!!Mount options for affs


__uid=__''value'' and
__gid=__''value''


Set the owner and group of the root of the file system
(default: uid=gid=0, but with option __uid__ or
__gid__ without specified value, the uid and gid of the
current process are taken).


__setuid=__''value'' and
__setgid=__''value''


Set the owner and group of all files.


__mode=__''value''


Set the mode of all files to ''value''
''


__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,
traditionally 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/''''


__uid=__''value'' and
__gid=__''value''


This sets the owner or the group of newly created PTYs to
the specified values. When nothing is specified, they will
be set to the UID and GID of the creating process. For
example, if there is a tty group with GID 5, then
__gid=5__ will cause newly created PTYs to belong to the
tty group.


__mode=__''value''


Set the mode of newly created PTYs to the specified value.
The default is 0600. A value of __mode=620__ and
__gid=5__ makes
__
!!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 system, 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 checking, 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 read-only, or panic and
halt the system.) The default is set in the filesystem
superblock, and can be changed using
__tune2fs__(8).


__grpid__ or __bsdgroups__ / __nogrpid__ or
__sysvgroups__


These options define what group id a newly created file
gets. When __grpid__ is set, it takes the group id of the
directory in which it is created; otherwise (the default) it
takes the fsgid of the current process, unless the directory
has the setgid bit set, in which case it takes the gid from
the parent directory, and also gets the setgid bit set if it
is a directory itself.


__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 damaged.
(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
__


__grpquota__ / __noquota__ / __quota__ /
__usrquota__


These options are accepted but ignored.


__nouid32__


Disables 32-bit UIDs and GIDs. This is for interoperability
with older kernels which only store and expect 16-bit
values.
!!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 current
format.


__journal=inum__


When a journal already exists, this option is ignored.
Otherwise, it specifies the number of the inode which will
represent the ext3 file system's journal file; ext3 will
create a new journal, overwriting the old contents of the
file whose inode number is ''inum''.


__noload__


Do not load the ext3 file system's journal on
mounting.


__data=journal__ / __data=ordered__ /
__data=writeback__


Specifies the journalling mode for file data. Metadata is
always journaled.


__journal__


All data is committed into the journal prior 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-throughput option. It guarantees internal file
system integrity, however it can allow old data to appear in
files after a crash and journal recovery.
!!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.


__check=__''value''


Three different levels of pickyness can be
chosen:


__r[[elaxed]__


Upper and lower case are accepted and equivalent, long name
parts are truncated (e.g. ''verylongname.foobar'' becomes
''verylong.foo''), leading and embedded spaces are
accepted in each name part (name and
extension).


__n[[ormal]__


Like


__s[[trict]__


Like


__codepage=__''value''


Sets the codepage for converting to shortname characters 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
''


__binary__


no translation is performed. This is the
default.


__text__


CRLF


__auto__


CRLF
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-kernel text
conversion. Several people have had their data ruined by
this translation. Beware!


For file systems mounted in binary mode, a conversion 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 list
of file system parameters will be printed (these data are
also printed if the parameters appear to be
inconsistent).


__fat=12__ / __fat=16__ / __fat=32__


Specify a 12, 16 or 32 bit fat. This overrides the automatic
FAT type detection routine. Use with caution!


__iocharset=__''value''


Character set to use for converting between 8 bit characters
and 16 bit Unicode characters. The default is iso8859-1.
Long filenames are stored on disk in Unicode
format.


__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 particular,
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


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 (except
that it is read-only, of course).


__norock__


Disable the use of Rock Ridge extensions, even if available.
Cf. __map__.


__nojoliet__


Disable the use of Microsoft Joliet extensions, even if
available. Cf. __map__.


__check=r[[elaxed]__ / __check=s[[trict]__


With __check=relaxed__, a filename is first converted to
lower case before doing the lookup. This is probably only
meaningful together with __norock__ and
__map=normal__. (Default:
__check=strict__.)


__uid=__''value'' and
__gid=__''value''


Give all files in the file system the indicated user or
group id, possibly overriding the information 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 settings 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.)
!!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 writeable
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,''
__mounthost=__''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__. For details,
see nfs(5).


Especially useful options include


__rsize=8192,wsize=8192__


This will make your nfs connection much faster than with the
default buffer size of 1024. (NFSv2 does not work with
larger values of __rsize__ and
__wsize__.)


__hard__


The program accessing a file on a NFS mounted file system
will hang when the server crashes. The process cannot be
interrupted or killed unless you also specify __intr__.
When the NFS server is back online the program will continue
undisturbed from where it was. This is probably what you
want.


__soft__


This option allows the kernel to time out if the nfs server
is not responding for some time. The time can be specified
with __timeo=time__. This option might be useful if your
nfs server sometimes doesn't respond or will be rebooted
while some process tries to get a file from the server.
Usually it just causes lots of trouble.


__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


__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 suppressed.


__uid=__''value'', __gid=__''value'' and
__umask=__''value''


Set the file permission on the filesystem. By default, the
files are owned by root and not readable by somebody
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 reiserfs


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 newly created
objects. This file system will no longer be compatible with
reiserfs 3.5 tools.


__hash=rupasov__ / __hash=tea__ / __hash=r5__ /
__hash=detect__


Choose which hash function reiserfs will use to find files
within directories.


__rupasov__


A hash invented by Yury Yu. Rupasov. It is fast and
preserves locality, mapping lexicographically close file
names to close hash values. This option should not be used,
as it causes a high probability of hash
collisions.


__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
collisions 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 function is in
use by examining the file system being mounted, and to write
this information 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 performance
improvements in some situations.


__no_unhashed_relocation__


Tunes the block allocator. This may provide performance
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 performance
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. Implementation 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''.


__resize=__''number''


A remount option which permits online expansion of reiserfs
partitions. Instructs reiserfs to assume that the device has
''number'' blocks. This option is designed for use with
devices which are under logical volume management (LVM).
There is a special ''resizer'' utility which can be
obtained from
''ftp://ftp.namesys.com/pub/reiserfsprogs''.
!!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


__gid=__


Set the default group.


__umask=__


Set the default umask.


__uid=__


Set the default user.


__unhide__


Show otherwise hidden files.


__undelete__


Show deleted files in lists.


__strict__


Set strict conformance (unused).


__utf8__


(unused).


__iocharset__


(unused).


__bs=__


Set the block size. (May not work unless 2048.)


__novrs__


Skip volume sequence recognition.


__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 operating
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.


__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.


__openstep__


For filesystems created by OpenStep (currently read
only).


__onerror=__''value''


Set behaviour on error:


__panic__


If an error is encountered, cause a kernel
panic.


__[[lock|umount|repair]__


These mount options don't do anything at 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
explicitly 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''. Furthermore, 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


__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 Unicode 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.
!!Mount options for xenix


None.
!!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 pagesize, 13 (8K bytes) is also a valid
''size''. The preferred 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
callouts.


__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 performance on some workloads at the cost of the
memory 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.


__norecovery__


The filesystem will be mounted without running log recovery.
If the filesystem was not cleanly unmounted, it is likely to
be inconsistent when mounted in __norecovery__ mode. Some
files or directories may not be accessible because of this.
Filesystems mounted __norecovery__ must be mounted
read-only or the mount will fail.


__osyncisdsync__


Make writes to files opened with the O_SYNC flag set behave
as if the O_DSYNC flag had been used instead. This can
result in better performance without compromising data
safety. However if this 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 losetup(8). If the mount requires a passphrase, you will be prompted for one unless you specify a file descriptor to read from instead with the __--pass-fd__ option. 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).
!!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__ (the
ext2 and ext3 file systems ''do'' support synchronous
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
__
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