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NTFS-3G(8) NTFS-3G(8)
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 '\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.
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 inter-
preted 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 spe-
cific 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 par-
ent 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 spe-
cial 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 map-
ping 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 usermap-
ping= 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. Alter-
nately, 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 mountabil-
ity 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 ntfs-3g-develATlists.net 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 (szakaATtuxera.com).
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 Andre, 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)
ntfs-3g 2011.4.12 February 2010 NTFS-3G(8)
