lowntfs-3g Man page

NTFS-3G(8) System Manager’s Manual NTFS-3G(8)


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


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


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.

Windows hibernation and fast restarting
On computers which can be dual-booted into Windows or Linux, Windows
has to be fully shut down before booting into Linux, otherwise the NTFS
file systems on internal disks may be left in an inconsistent state and
changes made by Linux may be ignored by Windows.

So, Windows may not be left in hibernation when starting Linux, in
order to avoid inconsistencies. Moreover, the fast restart feature
available on recent Windows systems has to be disabled. This can be
achieved by issuing as an Administrator the Windows command which dis‐
ables both hibernation and fast restarting :

powercfg /h off

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, exe‐
cution and directory browsing permissions. You can also assign permis‐
sions 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

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 permis‐
sions 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 rea‐
sons. This means that filenames are case sensitive and all characters
are allowed except ‘/’ and ‘\0’. 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.


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

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.

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.

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.

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.

Set standard permissions on created files and use standard
access control. This option is set by default when a user map‐
ping 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.

When creating a new file, set its initial protections according
to inheritance rules defined in parent directory. These rules
deviate from Posix specifications, but yield a better Windows
compatibility. The permissions option or a valid user mapping
file is required for this option to be effective.

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

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 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.

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.

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 ear‐
lier 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.

delay_mtime[= value] Only update the file modification time and the file change time
of a file when it is closed or when the indicated delay since
the previous update has elapsed. The argument is a number of
seconds, with a default value of 60. This is mainly useful for
big files which are kept open for a long time and written to
without changing their size, such as databases or file system
images mounted as loop.

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

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 dis‐
play the Windows trash bin directory by : “ls -ld ‘$RECY‐

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 list‐
ings, and when the flag is set they do not appear in Windows
directory displays either. When a file is renamed or linked
with a new name, the hidden flag is adjusted to the latest name.

This option prevents files, directories and extended attributes
to be created with a name not allowed by windows, because

– it contains some not allowed character,
– or the last character is a space or a dot,
– or the name is reserved.

The forbidden characters are the nine characters ” * / : < > ? \
| and those whose code is less than 0x20, and the reserved names
are CON, PRN, AUX, NUL, COM1..COM9, LPT1..LPT9, with no suffix
or followed by a dot.

Existing such files can still be read (and renamed).

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.

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 and on permission checking errors, when the permis‐
sions option is not set and no user mapping file is defined.
This option is on by default, and when set off (through option
no_def_opts) ownership and permissions parameters have to be

By default ntfs-3g acts as if “silent” (ignore permission errors
when permissions are not enabled), “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

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 utili‐
ties. The default is xattr.

Same as streams_interface=xattr.

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

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 Win‐
dows attribute. In such a directory, new files are created com‐
pressed and new subdirectories are themselves marked for com‐
pression. The option and the flag have no effect on existing
files. Currently this is the default option.

This option disables creating new transparently compressed files
in directories marked for compression. Existing compressed files
can still be read and updated.

This option prevents fuse from splitting write buffers into 4K
chunks, enabling big write buffers to be transferred from the
application in a single step (up to some system limit, generally
128K bytes).

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

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

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 recog‐

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 map‐
ping 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 cor‐
responding 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.


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 :


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

Mount /dev/sda1 to /mnt/windows:

ntfs-3g /dev/sda1 /mnt/windows
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
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 (the sixth and last field has to be zero
to avoid a file system check at boot time) :

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

Unmount /mnt/windows:

umount /mnt/windows

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.

Please see


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
ntfs-3g-devel@lists.sf.net address.

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

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


ntfs-3g.probe(8), ntfsprogs(8), attr(5), getfattr

ntfs-3g 2015.3.14AR.1 Mar 2014 NTFS-3G(8)