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

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. • A better solution can be found here This two questions should be linked! – user321419 Aug 28, 2014 at 20:39 ## 10 Answers 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. • here is good documentation. in short: sudo ntfs-3g.usermap /dev/disk/by-label/MY-NTFS and then sudo mv UserMapping /media/MY-NTFS/.NTFS-3G/ Jan 6, 2013 at 23:40 • So this will allow you to arbitrarily set permissions like chmod 655 /some/file on the NTFS partition mounted in Linux? I'm trying to figure out how to merge my home partition from linux into c:\Users. Will using usermap allow me to retain all the permissions? I was planning on mounting the c:\Users directory to /home in linux. Feb 13, 2014 at 7:22 • Let me re-emphasize your remark: "when no compatibility with Windows is needed". ref: askubuntu.com/questions/92863/… Sep 13, 2016 at 1:15 • ntfs-3g manpage link broken Sep 29, 2016 at 20:17 • Eduardo Cuomo wrote a pretty good example of all steps necessary to make a "User Mapping File" here: askubuntu.com/a/887502/327339 Apr 5, 2017 at 2:54 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  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. 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  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. • To execute binaries, use /lib64/ld-linux-x86-64.so.2 ./program.bin for 64-bit programs and /lib/ld-linux.so.2 ./program.bin for 32-bit ones. Apr 13, 2012 at 19:52 ## Check that Fast Startup is turned off If Windows uses Fast Startup, it is semi-hibernated, and its file system is 'dirty', and Linux mounts it read-only to avoid causing damage. Either reboot Windows (instead of shutdown) or turn off Fast Startup (a setting in Windows), and Linux is willing to mount the Windows file system with write access. ## Mount NTFS partition in a USB drive with custom permissions and owner In Linux the mode of NTFS (and FAT32 and exFAT) 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

• /media$sudo mkdir -p sdb1 /media$ sudo mount -o rw,users,umask=000,exec /dev/sdb1 ./sdb1/ mount: block device /dev/sdb1 is write-protected, mounting read-only Nov 29, 2017 at 16:02
• @alhelal, I am afraid that the hardware of your USB drive has become read-only or 'grid-locked'. But there might also be some problem with the file system, and if the file system is corrupted, you might be able to fix it by repairing it in Windows, either with the GUI method or with the command line chkdsk /f X: according to this link ubuntuforums.org/… -- If still no luck, backup the data and try according to askubuntu.com/questions/144852/… Nov 29, 2017 at 17:21
• You cannot change it via chmod. This is blatantly wrong. You CAN chmod/chown on an NTFS partition, if you use a usermap file. Just man ntfsusermap and you will see how. I've been chmodding NTFS partitions since ages. You could also read the NTFS-3G FAQs on how to do this: github.com/tuxera/ntfs-3g/wiki/… Jul 1, 2022 at 0:20
• Thanks for that link, @shivams. Jul 1, 2022 at 6:55

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.

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!

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 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! • ntfs-3g.usermap has been renamed to ntfsusermap on recent distributions -- see: askubuntu.com/a/996255/605262 Jun 6, 2020 at 21:24 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 :)

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.