How to '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

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 4

For NTFS partitions, use the permissions option in fstab.

First unmount the ntfs partition.

Then edit /etc/fstab

# Graphical 
gksu gedit /etc/fstab

# Command line
sudo -e /etc/fstab

Identify your partition UUID with blkid

sudo blkid

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 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

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 7

NTFS permissions work differently than those on linux. You cannot use chmod to modify those permissions.