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NTFS-3G


Section: Maintenance Commands (8)
Updated: February 2010
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NAME

ntfs-3g – Third Generation Read/Write NTFS Driver
 

SYNOPSIS

ntfs-3g

[-o option[,...]]
volume mount_point


mount -t ntfs-3g

[-o option[,...]]
volume mount_point


lowntfs-3g

[-o option[,...]]
volume mount_point


mount -t lowntfs-3g

[-o option[,...]]
volume mount_point

 

DESCRIPTION

ntfs-3g is an NTFS driver, which can create, remove, rename, move
files, directories, hard links, and streams; it can read and write files,
including streams, sparse files and transparently compressed files; it can
handle special files like symbolic links, devices, and FIFOs; moreover it
provides standard management of file ownership and permissions, including
POSIX ACLs.

It comes in two variants ntfs-3g and lowntfs-3g with
a few differences mentioned below in relevant options descriptions.

The volume to be mounted can be either a block device or
an image file.
 

Access Handling and Security

By default, files and directories are owned by the effective
user and group of the mounting process, and everybody has
full read, write, execution and directory browsing permissions.
You can also assign permissions to a single user by using the
uid

and/or the
gid

options together with the
umask,

or
fmask

and
dmask

options.

Doing so, Windows users have full access to the files created by
ntfs-3g.

But, by setting the permissions option, you can benefit from the full
ownership and permissions features as defined by POSIX. Moreover, by defining
a Windows-to-Linux user mapping, the ownerships and permissions are even
applied to Windows users and conversely.

If
ntfs-3g

is set setuid-root then non-root users will
be also able to mount volumes.
 

Windows Filename Compatibility

NTFS supports several filename namespaces: DOS, Win32 and POSIX. While the
ntfs-3g driver handles all of them, it always creates new files in the
POSIX namespace for maximum portability and interoperability reasons.
This means that filenames are case sensitive and all characters are
allowed except ‘/’ and ‘’. This is perfectly legal on Windows, though
some application may get confused. The option windows_names may be
used to apply Windows restrictions to new file names.
 

Alternate Data Streams (ADS)

NTFS stores all data in streams. Every file has exactly one unnamed
data stream and can have many named data streams. The size of a file is the
size of its unnamed data stream. By default, ntfs-3g will only read
the unnamed data stream.

By using the options "streams_interface=windows", with the ntfs-3g driver
(not possible with lowntfs-3g), you will be able to read any named data
streams, simply by specifying the stream’s name after a colon.
For example:



cat some.mp3:artist


Named data streams act like normal files, so you can read from them, write to
them and even delete them (using rm). You can list all the named data streams
a file has by getting the "ntfs.streams.list" extended attribute.
 

OPTIONS

Below is a summary of the options that ntfs-3g accepts.


uid=value and gid=value

Set the owner and the group of files and directories. The values are numerical.
The defaults are the uid and gid of the current process.
umask=value


Set the bitmask of the file and directory permissions that are not
present. The value is given in octal. The default value is 0 which
means full access to everybody.
fmask=value


Set the bitmask of the file permissions that are not present.
The value is given in octal. The default value is 0 which
means full access to everybody.
dmask=value


Set the bitmask of the directory permissions that are not
present. The value is given in octal. The default value is 0 which
means full access to everybody.
usermapping=file-name


Use file file-name as the user mapping file instead of the default
.NTFS-3G/UserMapping. If file-name defines a full path, the
file must be located on a partition previously mounted. If it defines a
relative path, it is interpreted relative to the root of NTFS partition
being mounted.


When a user mapping file is defined, the options uid=, gid=,
umask=, fmask=, dmask= and silent are ignored.


permissions


Set standard permissions on created files and use standard access control.
This option is set by default when a user mapping file is present.
acl


Enable setting Posix ACLs on created files and use them for access control.
This option is only available on specific builds. It is set by default
when a user mapping file is present and the
permissions

mount option is not set.

inherit


When creating a new file, set its initial ownership and protections
according to inheritance rules defined in parent directory. These rules
deviate from Posix specifications, but yield a better Windows
compatibility.
ro


Mount filesystem read-only. Useful if Windows is hibernated or the
NTFS journal file is unclean.
locale=value


This option can be useful when wanting a language specific locale environment.
It is however discouraged as it leads to files with untranslatable chars
to not be visible.
force


This option is obsolete. It has been superseded by the recover and
norecover options.
recover


Recover and try to mount a partition which was not unmounted properly by
Windows. The Windows logfile is cleared, which may cause inconsistencies.
Currently this is the default option.
norecover


Do not try to mount a partition which was not unmounted properly by Windows.
ignore_case (only with lowntfs-3g)


Ignore character case when accessing a file (FOO, Foo, foo,
etc. designate the same file). All files are displayed with lower case in
directory listings.
remove_hiberfile


Unlike in case of read-only mount, the read-write mount is denied if
the NTFS volume is hibernated. One needs either to resume Windows and
shutdown it properly, or use this option which will remove the Windows
hibernation file. Please note, this means that the saved Windows
session will be completely lost. Use this option under your own
responsibility.
atime, noatime, relatime


The
atime

option updates inode access time for each access.


The
noatime

option disables inode access time updates which can speed up
file operations and prevent sleeping (notebook) disks spinning
up too often thus saving energy and disk lifetime.


The
relatime

option is very similar to
noatime.

It updates inode access times relative to modify or change time.
The access time is only updated if the previous access time was earlier
than the current modify or change time. Unlike
noatime

this option doesn’t break applications that need to know
if a file has been read since the last time it was modified.
This is the default behaviour.

show_sys_files


Show the metafiles in directory listings. Otherwise the default behaviour is
to hide the metafiles, which are special files used to store the NTFS
structure. Please note that even when this option is specified, "$MFT" may
not be visible due to a glibc bug. Furthermore, irrespectively of
show_sys_files, all files are accessible by name, for example you can always
do
"ls -l ‘$UpCase’".
hide_hid_files


Hide the hidden files and directories in directory listings, the hidden files
and directories being the ones whose NTFS attribute have the hidden flag set.
The hidden files will not be selected when using wildcards in commands,
but all files and directories remain accessible by full name, for example you
can always display the Windows trash bin directory by :
"ls -ld ‘$RECYCLE.BIN’".
hide_dot_files


Set the hidden flag in the NTFS attribute for created files and directories
whose first character of the name is a dot. Such files and directories
normally do not appear in directory listings, and when the flag is set
they do not appear in Windows directory displays either.
windows_names


This option prevents files, directories and extended attributes to be
created with a name not allowed by windows, either because it contains
some not allowed character (which are the nine characters " * / : < > ? | and
those whose code is less than 0x20) or because the last character is a space
or a dot. Existing such files can still be read (and renamed).
allow_other


This option overrides the security measure restricting file access
to the user mounting the filesystem. This option is only
allowed to root, but this restriction can be overridden by
the ‘user_allow_other’ option in the /etc/fuse.conf file.
max_read=value


With this option the maximum size of read operations can be set.
The default is infinite. Note that the size of read requests is
limited anyway to 32 pages (which is 128kbyte on i386).
silent


Do nothing, without returning any error, on chmod and chown operations,
when the permissions option is not set and no user mapping file
is defined. This option is on by default.
no_def_opts


By default ntfs-3g acts as if "silent" (ignore errors on chmod and chown),
"allow_other" (allow any user to access files) and "nonempty"
(allow mounting on non-empty directories) were set, and "no_def_opts"
cancels these default options.
streams_interface=value


This option controls how the user can access Alternate Data Streams (ADS) or
in other words, named data streams. It can be set to, one of none,
windows or xattr. If the option is set to none, the user
will have no access to the named data streams. If it is set to windows
(not possible with lowntfs-3g), then the user can access them just like in
Windows (eg. cat file:stream). If it’s set to xattr, then the named
data streams are mapped to xattrs and user can manipulate them using
{get,set}fattr utilities. The default is xattr.
user_xattr


Same as streams_interface=xattr.
efs_raw


This option should only be used in backup or restore situation.
It changes the apparent size of files and the behavior of read and
write operation so that encrypted files can be saved and restored
without being decrypted. The user.ntfs.efsinfo extended attribute
has also to be saved and restored for the file to be decrypted.
compression


This option enables creating new transparently compressed files in
directories marked for compression. A directory is marked for compression by
setting the bit 11 (value 0x00000800) in its Windows attribute. In such a
directory, new files are created compressed and new subdirectories are
themselves marked for compression. The option and the flag have no effect
on existing files.
nocompression


This option disables creating new transparently compressed files in directories
marked for compression. Existing compressed files can still be read and
updated. Currently this is the default option.
debug


Makes ntfs-3g to print a lot of debug output from libntfs-3g and FUSE.
no_detach


Makes ntfs-3g to not detach from terminal and print some debug output.

 

USER MAPPING

NTFS uses specific ids to record the ownership of files instead of
the uid and gid used by Linux. As a consequence a mapping
between the ids has to be defined for ownerships to be recorded into
NTFS and recognized.

By default, this mapping is fetched from the file .NTFS-3G/UserMapping
located in the NTFS partition. The option usermapping= may be used
to define another location. When the option permissions is set and
no mapping file is found, a default mapping is used.

Each line in the user mapping file defines a mapping. It is organized
in three fields separated by colons. The first field identifies a uid,
the second field identifies a gid and the third one identifies the
corresponding NTFS id, known as a SID. The uid and the gid
are optional and defining both of them for the same SID is not
recommended.

If no interoperation with Windows is needed, you can use the option
permissions to define a standard mapping. Alternately, you may define
your own mapping by setting a single default mapping with no uid and gid. In
both cases, files created on Linux will appear to Windows as owned by a
foreign user, and files created on Windows will appear to Linux as owned by
root. Just copy the example below and replace the 9 and 10-digit numbers by
any number not greater than 4294967295. The resulting behavior is the same as
the one with the option permission set with no ownership option and no user
mapping file available.



::S-1-5-21-3141592653-589793238-462643383-10000


If a strong interoperation with Windows is needed, the mapping has to be
defined for each user and group known in both system, and the SIDs used
by Windows has to be collected. This will lead to a user mapping file like :



john::S-1-5-21-3141592653-589793238-462643383-1008

mary::S-1-5-21-3141592653-589793238-462643383-1009

:smith:S-1-5-21-3141592653-589793238-462643383-513

::S-1-5-21-3141592653-589793238-462643383-10000


The utility ntfs-3g.usermap may be used to create such a user
mapping file.
 

EXAMPLES

Mount /dev/sda1 to /mnt/windows:



ntfs-3g /dev/sda1 /mnt/windows

or


mount -t ntfs-3g /dev/sda1 /mnt/windows


Mount the ntfs data partition /dev/sda3 to /mnt/data with standard Linux
permissions applied :



ntfs-3g -o permissions /dev/sda3 /mnt/data

or


mount -t ntfs-3g -o permissions /dev/sda3 /mnt/data


Read-only mount /dev/sda5 to /home/user/mnt and make user with uid 1000
to be the owner of all files:



ntfs-3g /dev/sda5 /home/user/mnt -o ro,uid=1000


/etc/fstab entry for the above:


/dev/sda5 /home/user/mnt ntfs-3g ro,uid=1000 0 0


Unmount /mnt/windows:



umount /mnt/windows


 

EXIT CODES

To facilitate the use of the
ntfs-3g

driver in scripts, an exit code is returned to give an indication of the
mountability status of a volume. Value 0 means success, and all other
ones mean an error. The unique error codes are documented in the
ntfs-3g.probe(8)

manual page.
 

KNOWN ISSUES

Please see



http://www.tuxera.com/support/


for common questions and known issues.
If you would find a new one in the latest release of
the software then please send an email describing it
in detail. You can contact the
development team on the [email protected]
address.
 

AUTHORS

ntfs-3g

was based on and a major improvement to ntfsmount and libntfs which were
written by Yura Pakhuchiy and the Linux-NTFS team. The improvements were
made, the ntfs-3g project was initiated and currently led by long time
Linux-NTFS team developer Szabolcs Szakacsits ([email protected]).
 

THANKS

Several people made heroic efforts, often over five or more
years which resulted the ntfs-3g driver. Most importantly they are
Anton Altaparmakov, Jean-Pierre André, Richard Russon, Szabolcs Szakacsits,
Yura Pakhuchiy, Yuval Fledel, and the author of the groundbreaking FUSE
filesystem development framework, Miklos Szeredi.
 

SEE ALSO

ntfs-3g.probe(8),

ntfsprogs(8),

attr(5),

getfattr(1)



 

Index



NAME

SYNOPSIS

DESCRIPTION


Access Handling and Security

Windows Filename Compatibility

Alternate Data Streams (ADS)


OPTIONS

USER MAPPING

EXAMPLES

EXIT CODES

KNOWN ISSUES

AUTHORS

THANKS

SEE ALSO



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