mount.8

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.TP
.BR replayonly
Replay the transactions which are in the journal, but do not actually
mount the file system. Mainly used by
.IR reiserfsck .
.TP
.BI resize= number
A remount option which permits online expansion of reiserfs partitions.
Instructs reiserfs to assume that the device has
.I number
blocks.
This option is designed for use with devices which are under logical
volume management (LVM).
There is a special
.I resizer
utility which can be obtained from
.IR ftp://ftp.namesys.com/pub/reiserfsprogs .

.SH "Mount options for romfs"
None.

.SH "Mount options for smbfs"
Just like
.IR nfs ", the " smbfs
implementation expects a binary argument (a
.IR "struct smb_mount_data" )
to the mount system call. This argument is constructed by
.BR smbmount (8)
and the current version of
.B mount
(2.12) does not know anything about smbfs.

.SH "Mount options for sysv"
None.

.SH "Mount options for tmpfs"
The following parameters accept a suffix
.BR k ,
.B m
or
.B g
for Ki, Mi, Gi (binary kilo, mega and giga) and can be changed on remount.
.TP
.BI 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.
.TP
.B nr_blocks=
Set number of blocks.
.TP
.B nr_inodes=
Set number of inodes.
.TP
.B mode=
Set initial permissions of the root directory.

.SH "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
.IR iso9660 .
.TP
.B gid=
Set the default group.
.TP
.B umask=
Set the default umask.
The value is given in octal.
.TP
.B uid=
Set the default user.
.TP
.B unhide
Show otherwise hidden files.
.TP
.B undelete
Show deleted files in lists.
.TP
.B strict
Set strict conformance (unused).
.TP
.B utf8
(unused).
.TP
.B iocharset
(unused).
.TP
.B bs=
Set the block size. (May not work unless 2048.)
.TP
.B novrs
Skip volume sequence recognition.
.TP
.B session=
Set the CDROM session counting from 0. Default: last session.
.TP
.B anchor=
Override standard anchor location. Default: 256.
.TP
.B volume=
Override the VolumeDesc location. (unused)
.TP
.B partition=
Override the PartitionDesc location. (unused)
.TP
.B lastblock=
Set the last block of the filesystem.
.TP
.B fileset=
Override the fileset block location. (unused)
.TP
.B rootdir=
Override the root directory location. (unused)

.SH "Mount options for ufs"
.TP
.BI 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:
.RS
.TP
.B old
Old format of ufs, this is the default, read only.
(Don't forget to give the \-r option.)
.TP
.B 44bsd
For filesystems created by a BSD-like system (NetBSD,FreeBSD,OpenBSD).
.TP
.B sun
For filesystems created by SunOS or Solaris on Sparc.
.TP
.B sunx86
For filesystems created by Solaris on x86.
.TP
.B hp
For filesystems created by HP-UX, read-only.
.TP
.B nextstep
For filesystems created by NeXTStep (on NeXT station) (currently read only).
.TP
.B nextstep-cd
For NextStep CDROMs (block_size == 2048), read-only.
.TP
.B openstep
For filesystems created by OpenStep (currently read only).
The same filesystem type is also used by Mac OS X.
.RE

.TP
.BI onerror= value
Set behaviour on error:
.RS
.TP
.B panic
If an error is encountered, cause a kernel panic.
.TP
.B [lock|umount|repair]
These mount options don't do anything at present;
when an error is encountered only a console message is printed.
.RE

.SH "Mount options for umsdos"
See mount options for msdos.
The
.B dotsOK
option is explicitly killed by
.IR umsdos .

.SH "Mount options for vfat"
First of all, the mount options for
.I fat
are recognized.
The
.B dotsOK
option is explicitly killed by
.IR vfat .
Furthermore, there are
.TP
.B 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).
.TP
.B posix
Allow two files with names that only differ in case.
.TP
.B nonumtail
First try to make a short name without sequence number,
before trying
.IR name~num.ext .
.TP
.B 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.
.TP
.B 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:
.RS
.TP
.I lower
Force the short name to lower case upon display; store a long name when 
the short name is not all upper case.
.TP
.I win95
Force the short name to upper case upon display; store a long name when
the short name is not all upper case.
.TP
.I winnt
Display the shortname as is; store a long name when the short name is 
not all lower case or all upper case.
.TP
.I mixed
Display the short name as is; store a long name when the short name is not
all upper case.
.RE

The default is "lower".

.SH "Mount options for usbfs"
.TP
\fBdevuid=\fP\fIuid\fP and \fBdevgid=\fP\fIgid\fP and \fBdevmode=\fP\fImode\fP
Set the owner and group and mode of the device files in the usbfs file system
(default: uid=gid=0, mode=0644). The mode is given in octal.
.TP
\fBbusuid=\fP\fIuid\fP and \fBbusgid=\fP\fIgid\fP and \fBbusmode=\fP\fImode\fP
Set the owner and group and mode of the bus directories in the usbfs
file system (default: uid=gid=0, mode=0555). The mode is given in octal.
.TP
\fBlistuid=\fP\fIuid\fP and \fBlistgid=\fP\fIgid\fP and \fBlistmode=\fP\fImode\fP
Set the owner and group and mode of the file
.I devices
(default: uid=gid=0, mode=0444). The mode is given in octal.

.SH "Mount options for xenix"
None.

.SH "Mount options for xfs"
.TP
.BI biosize= size
Sets the preferred buffered I/O size (default size is 64K).
.I 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
.IR size .
The preferred buffered I/O size can also be altered on an individual
file basis using the
.BR ioctl (2)
system call.
.TP
.B dmapi " / " xdsm
Enable the DMAPI (Data Management API) event callouts.
.TP
.BI 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.
.TP
.BI 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.
.TP
\fBlogdev=\fP\fIdevice\fP and \fBrtdev=\fP\fIdevice\fP
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
.BR xfs (5).
.TP
.B noalign
Data allocations will not be aligned at stripe unit boundaries.
.TP
.B noatime
Access timestamps are not updated when a file is read.
.TP
.B 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
.B norecovery
mode.
Some files or directories may not be accessible because of this.
Filesystems mounted
.B norecovery
must be mounted read-only or the mount will fail.
.TP
.B 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.
.TP
.BR quota " / " usrquota " / " uqnoenforce
User disk quota accounting enabled, and limits (optionally) enforced.
.TP
.BR grpquota " / " gqnoenforce
Group disk quota accounting enabled and limits (optionally) enforced.
.TP
\fBsunit=\fP\fIvalue\fP and \fBswidth=\fP\fIvalue\fP
Used to specify the stripe unit and width for a RAID device or a stripe
volume.
.I 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
.B swidth
option is required if the
.B sunit
option has been specified,
and must be a multiple of the
.B sunit
value.

.SH "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.

.SH "THE LOOP DEVICE"
One further possible type is a mount via the loop device. For example,
the command

.nf
.B "  mount /tmp/fdimage /mnt -t msdos -o loop=/dev/loop3,blocksize=1024"
.fi

will set up the loop device
.I /dev/loop3
to correspond to the file
.IR /tmp/fdimage ,
and then mount this device on
.IR /mnt .
This type of mount knows about three options, namely
.BR loop ", " offset " and " encryption ,
that are really options to
.BR losetup (8).
If no explicit loop device is mentioned
(but just an option `\fB\-o loop\fP' is given), then
.B mount
will try to find some unused loop device and use that.
If you are not so unwise as to make
.I /etc/mtab
a symbolic link to
.I /proc/mounts
then any loop device allocated by
.B mount
will be freed by
.BR umount .
You can also free a loop device by hand, using `losetup -d', see
.BR losetup (8).

.SH RETURN CODES
.B mount
has the following return codes (the bits can be ORed):
.TP
.BR 0
success
.TP
.BR 1
incorrect invocation or permissions
.TP
.BR 2
system error (out of memory, cannot fork, no more loop devices)
.TP
.BR 4
internal
.B mount
bug or missing
.BR nfs
support in
.B mount
.TP
.BR 8
user interrupt
.TP
.BR 16
problems writing or locking /etc/mtab
.TP
.BR 32
mount failure
.TP
.BR 64
some mount succeeded

.SH FILES
.I /etc/fstab
file system table
.br
.I /etc/mtab
table of mounted file systems
.br
.I /etc/mtab~
lock file
.br
.I /etc/mtab.tmp
temporary file
.SH "SEE ALSO"
.BR mount (2),
.BR umount (2),
.BR fstab (5),
.BR umount (8),
.BR swapon (8),
.BR nfs (5),
.BR xfs (5),
.BR e2label (8),
.BR xfs_admin (8),
.BR mountd (8),
.BR nfsd (8),
.BR mke2fs (8),
.BR tune2fs (8),
.BR losetup (8)
.SH BUGS
It is possible for a corrupted file system to cause a crash.
.PP
Some Linux file systems don't support
.B "\-o sync and \-o dirsync"
(the ext2 and ext3 file systems
.I do
support synchronous updates (a la BSD) when mounted with the
.B sync
option).
.PP
The
.B "\-o remount"
may not be able to change mount parameters (all
.IR ext2fs -specific
parameters, except
.BR  sb ,
are changeable with a remount, for example, but you can't change
.B gid
or
.B umask
for the
.IR fatfs ).
.SH HISTORY
A
.B mount
command existed in Version 5 AT&T UNIX.