How do I use 'chmod' on an NTFS (or FAT32) partition?

Question

I have a script that I need to execute on an NTFS partition. The script's permission is set to 600.

I attempted to modify the permissions by running chmod 755 script.sh, which doesn't report a failure or anything - but it also doesn't change the permissions on the file:

$ stat script.sh

  File: `script.sh'
  Size: 297070      Blocks: 584        IO Block: 4096   regular file
Device: 811h/2065d  Inode: 35515       Links: 1
Access: (0600/-rw-------)  Uid: ( 1000/  xxxxxx)   Gid: ( 1000/  xxxxxx)
Access: 2010-09-30 14:05:16.041621000 -0700
Modify: 2010-09-30 14:05:05.070157000 -0700
Change: 2010-09-30 14:05:05.070475000 -0700

$ chmod 755 script.sh
$ stat script.sh

  File: `script.sh'
  Size: 297070      Blocks: 584        IO Block: 4096   regular file
Device: 811h/2065d  Inode: 35515       Links: 1
Access: (0600/-rw-------)  Uid: ( 1000/  xxxxxx)   Gid: ( 1000/  xxxxxx)
Access: 2010-09-30 14:05:16.041621000 -0700
Modify: 2010-09-30 14:05:05.070157000 -0700
Change: 2010-09-30 14:05:05.070475000 -0700

As you can see, it remains unchanged.

Answer 1

The mode is determined by the partition's mount options (you cannot change it via chmod).

For '755' on files and '777' on directories you would use something like

sudo mount -t ntfs -o rw,auto,user,fmask=0022,dmask=0000 /dev/whatever /mnt/whatever

Answer 2

Contrary to what most people believe, NTFS is a POSIX-compatible¹ filesystem, and it is possible to use permissions on NTFS.

To enable this, you need a "User Mapping File" or just give the permissions option when mounting (when no compatibility with Windows is needed). This maps linux users on your system with the user IDs like NTFS/Windows use them internally.

See the ntfs-3g manpage for some info and some examples. If you need more information, see the ntfs-3g advanced documentation about ownership and permissions.

(Note that this does not work on FAT filesystems.)

¹ Yes, it can also store filenames that are valid in linux/unix but not under Windows, supports symlinks & hardlinks, etc.

Answer 3

For NTFS partitions, use the permissions option in fstab.

First unmount the ntfs partition.

Identify your partition UUID with blkid

sudo blkid

Then edit /etc/fstab

# Graphical 
gksu gedit /etc/fstab

# Command line
sudo -e /etc/fstab

And add or edit a line for the ntfs partition

# change the "UUID" to your partition UUID
UUID=12102C02102CEB83 /media/windows ntfs-3g auto,users,permissions 0 0

Make a mount point (if needed)

sudo mkdir /media/windows

Now mount the partition

mount /media/windows

The options I gave you, auto, will automatically mount the partition when you boot and users allows users to mount and umount .

You can then use chown and chmod on the ntfs partition.

Answer 4

In addition to setting the fmask and/or dmask in htorque's answer above, if you want to execute scripts on the drive, I had to also set the "exec" mount option.

So the example would be:

sudo mount -t ntfs -o rw,auto,user,fmask=0022,dmask=0000,exec /dev/whatever /mnt/whatever

Answer 5

You can always explicitly invoke the script interpreter, in which case execution permissions are not required. If the script uses bash, as can be verified by looking at the first line of the script, just run

bash script.sh

Note that the script calls other scripts or binaries on the same partition, this won't work. Note also that the strategy doesn't work with binaries as opposed to textual script files written in Bash Script, Perl, Python or the like.

Answer 6

According to the Ownership and Permissions section of the NTFS-3G documentation, we can use mount options to control file access and creation. The combinations are very complicated (see the two tables there). Also I do not read and get all of them. For example, I do not know whether POSIX ACLs is selected at compile-time or not of the NTFS-3G binary package. But the best I have come out is using a User Mapping file combined with some mount options to approximate a plausible mapping of file ownership and permissions between Windows and Linux.

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Warning: This is only what works best for my sharing a NTFS data partition (drive D: on Windows) between dual-booted Windows 8 and Kubuntu 14.04. The instructions are recorded in careful retrospection but not thoroughly tested. It is too tiring and tedious to repeat the whole procedure again. So follow it at your own risk. But if you do, share back your experience. If you decide to follow the instructions, please read it fully to have a whole picture before actually acting. Good luck!

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Alright, here you go! The detailed instructions consist of three parts. Part 1 should be carried out on Windows while Part 2 on Linux. Part 3 is for test.

Part 1

The User Mapping section of the NTFS-3G documentation specifies two versions to set up user mapping between Windows and Linux, one Windows version and one Linux version. My experience was that the Linux version ended up with a miss. The Linux account was not mapped to my Windows account but some unknown account appeared under an SID. The result was a mess since this unknown account takes ownership of all files of my Windows account. In that situation, unless you have an administrative privilege to take your ownership back, files under your Windows account become inaccessible. But even if you mange, it is still a wrong mapping. That means, later whatever files you create on Linux get assigned to that unknown account on Windows and those on Windows get assigned to root on Linux (if I remember correctly). So on Windows you need to take ownership back again and on Linux change ownership. That is not what we expect it to be. After several hopeless attempts to fix the issue, I gave up and turned to the Windows version. That one worked. Detailed instructions extracted from the relevant section of the NTFS-3G documentation follow:

1. Download the usermap tool, extract it somewhere (in my case, drive C:), better outside the NTFS partition (in my case drive D:) to be shared.

2. Open the Windows command line. Change to the extracted directory tools (by default) of the usermap tool. Then run the following command:

   C:\tools> mapuser > UserMapping
   

   This generates a template and redirects it to a file named UserMapping. Open the file with a text editor, say Notepad, you should see the following lines:

   # Generated by usermap for Windows, v 1.1.5
   # For Windows account "Account" in domain "Domain"
   # Replace "user" and "group" hereafter by matching Linux login
   user::SID
   :group:SID
   

   Presumably, the first SID should be your user SID while the second your group SID. You can check them respectively by commands whoami /user and whoami /groups.

3. After you make sure the SIDs are correct, following the instructions in the comment, that is, change user in the user::SID line to your user name and group in the :group:SID line to your primary group name on Linux. On Ubuntu, they are the same. Moreover, add your Linux group name also after the first colon of the user::SID line. So the line should look something like user:group:SID. It seems that if not doing so files created on Windows will be assigned to user:root on Linux.

4. Save the file. Move it to a directory named .NTFS-3G (create it if not existent yet) on the NTFS partition to be shared (in my case drive D:).

5. This step is for test in Part 3. On the shared NTFS partition, create a new directory and a new file.

Part 2

Now boot into Linux. sudo edit the file /etc/fstab. Add or modify the line for the shared NTFS partition to something like the following:

UUID=...    /data    ntfs    defaults,umask=077,utf8    0    0

The essential is to set the umask (dmask and fmask may also work but not tested). Pick a value for umask you like, although I picked 077. It seems without this setting, full permissions will be given to others for newly-created files.

Save the file. Now sudo mount or remount (sudo umount and then sudo mount) the shared NTFS partition (in my case /data):

$ sudo mount /data

Part 3

Now (still on Linux) cd to the mount point (in my case, /data), ls -l the files there. Check whether their ownership and permissions match respectively that you specified in the UserMapping file and the umask you set in /etc/fstab (the match between permissions and umask requires some complement calculation, see man (1) umask for more information). If they do, congratulations, half goal is achieved. Otherwise, poor you. Ask Ubuntu or Windows.

Then create a new directory and a new file. ls -l to check their ownership and permissions. The ownership should be your user name and primary group as usual. The permissions should match the umask. Now restart your computer and boot into Windows. Locate on the shared NTFS partition the directory and file you just created on Linux. Check their properties to see if they are assigned to your Windows account. If they are, congratulations, you are all done. Otherwise, bad luck. Ask Windows or Ubuntu.

EOF

Answer 7

Old thread, I know, but still relevant and missing a particular use case tip, composed from different suggestions on various other forums/threads and tested on Ubuntu GNOME 13.04 where I wanted an external drive to hold a Steam library...

When the NTFS partition is on an external usb drive, for example -- which means the partition is mounted on the fly upon connection -- then you can use the following method to make udev mount ntfs partitions with execution rights.

Open a terminal window and do:

$ sudo nano /etc/udev/rules.d/90-usb-disks.rules

Then paste this line in what should be a blank/new file (if not, then exit nano and reissue the command but starting the file name with a higher number like 91-...):

ENV{ID_FS_TYPE}=="ntfs", ENV{ID_FS_TYPE}="ntfs-3g"

Then save and close. Unplug the drive and then do in terminal:

$ sudo service udev restart

Next, plug the drive back in and enjoy :)

Answer 8

All steps:

1. Install ntfs-3g:

   sudo apt-get install -y ntfs-3g
   

2. Unmount NTFS partition:

   sudo umount /mnt/windows
   

3. Use ntfs-3g.usermap to generate your UserMapping file:

   sudo ntfs-3g.usermap /dev/disk/by-label/MY-NTFS
   

   or

   sudo ntfs-3g.usermap /dev/sdb1
   

4. Remount NTFS partition to add UserMapping file:

   mount -a
   sudo mkdir /mnt/windows/.NTFS-3G
   sudo mv UserMapping /mnt/windows/.NTFS-3G/
   

5. Update your fstab file:

   sudo vim /etc/fstab
   

   Update mount line:

   1. Backup your current mount line! Duplicate the line and comment it by adding a # at the beginning.
   2. Change next: UUID=34A0456DA04536A0 /mnt/windows ntfs defaults,uid=1000,gid=1000 0 0
   3. By next: UUID=34A0456DA04536A0 /mnt/windows ntfs-3g defaults 0 0 (Use ntfs-3g and only default option)

   It should look something like this:

   #UUID=34A0456DA04536A0 /mnt/windows ntfs defaults,uid=1000,gid=1000 0 0 UUID=34A0456DA04536A0 /mnt/windows ntfs-3g defaults 0 0

6. Finally, remount using your fstab:

   sudo umount /mnt/windows
   sudo mount -a
   

Do this once for every NTFS partition you have!

WARNING WITH WINDOWS OS!

I check it with Windows 7+ and the permissions affect Windows OS! I change the permissions of my Home Directory on Windows partition, and when I used Windows again I could see that the user was broken!

Answer 9

There is n related question for USB devices. This answer provides an ugly hack if you want to mount every USB device automatically with execute permissions.

Answer 10

Mount NTFS partition in a USB drive with custom permissions and owner

In Linux the mode of NTFS (and FAT32) is determined by the partition's mount options. You cannot change it via chmod.

Assumption: the USB drive is seen as sdb1, modify to match the drive letter and partition number in your case. The general syntax is sdxn, where x is the drive letter and n is the partition number as seen by for example sudo lsblk -f

Preparing

• Unmount the NTFS partition.

  sudo umount /dev/sdxn   # general syntax
  sudo umount /dev/sdb1   # modify to match your case
  

• Create a custom mountpoint (only if you want a new mountpoint), for example with

  sudo mkdir -p /mnt/sd1
  

• Check your userID's uid number (it is usually 1000, sometimes 1001 or 1002 ...)

  grep ^"$USER" /etc/group
  

  and use that number if you want to grab ownership (default is root).

Mount the NTFS partition

Example 1 (without execute permissions for files, no access for 'others'),

sudo mount -o rw,user,uid=1000,dmask=007,fmask=117 /dev/sdxn /mnt/sd1  # general syntax
sudo mount -o rw,user,uid=1000,dmask=007,fmask=117 /dev/sdb1 /mnt/sd1  # modify to match your case

• in this case you can run the script this-script with

  bash /mnt/sd1/this-script
  

Example 2 (with execute permissions for files, no access for 'others'),

sudo mount -o rw,user,uid=1000,umask=007,exec /dev/sdxn /mnt/sd1  # general syntax
sudo mount -o rw,user,uid=1000,umask=007,exec /dev/sdb1 /mnt/sd1  # modify to match your case

• In this case you can run the script this-script with

  /mnt/sd1/this-script
  

  and you can run executable programs too from this location (not that it is recommended).

Example 3 (full permissions for everybody, which is convenient but not safe, when there are several users),

sudo mount -o rw,users,umask=000,exec /dev/sdxn /mnt/sd1  # general
sudo mount -o rw,users,umask=000,exec /dev/sdb1 /mnt/sd1  # modify to match your case