How do I give permission to a basic user to access read, execute contents of only one partition but not delete or ad files ... I have 3 partitions , and the one I want to give access is dev/sda4 . Every time I try to mount disc it requires authentication.
1 Answer
First thing is first, Reading/Writing/Deleting from a filesystem on a partition are managed by a different set of permissions than mounting a filesystem on a partition. So you will need two fixes, at the minimum, to solve your problem.
Relevant to Both Fixes
inside of the file /etc/fstab
there may or may not be a line starting with /dev/sda4
. Alternatively there may or may not be a line starting with the UUID of that partition. You can find the UUID by running ls -l /dev/disk/by-uuid
and looking for the one that points to /dev/sda4
.
If there isn't a line, then you'll need to make one. Either way, the general form of the line should be:
UUID=(hex chars) /mntdir filesystem options 0 0
#or
/dev/sda4 /mntdir filesystem options 0 0
The part of the line you want to focus on is the options section.
Fix #1, Relevant if your filesystem is FAT/NTFS
If your filesystem doesn't play nice with linux permissions, then you can use the umask
option to control the type of access to the files. On NTFS-3G, umask=0022
sets the user file permissions to 0755
which is rwxr-xr-x
. gid
controls what group the default permissions apply to. So for example, you can make a group called ntfsusers
and add all users to that group and then set umask=0002
See the Arch Wiki link for more.
#Example NTFS line:
/dev/sda4 /mntdir ntfs gid=users,umask=0002,user,rw,auto 0 0
Fix #2, Mounting the driver as a normal user
The user
and nouser
options control who can mount the filesytem. When user
is present any user can mount the drive. When nouser
is present only root can mount the drive. user
turns on a few other flags by default, see the link at the bottom of this post.
#Example NTFS line:
/dev/sda4 /mntdir ext3 defaults,user 0 0
Wikipedia on /etc/fstab
: http://en.wikipedia.org/wiki/Fstab
Tuxfiles on /etc/fstab
: http://www.tuxfiles.org/linuxhelp/fstab.html
Arch-Wiki on NTFS-3G options: https://wiki.archlinux.org/index.php/NTFS-3G#Allowing_Group.2FUser
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1You gave a lot of precious information, but in my view you forgot the final part of the answer inside the links. Maybe this is nice to incentive some self-exploration?– H_7Feb 13, 2012 at 5:41
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1When it comes to permissions, every scenario is unique. In my experience, it is best to indicate the gist of the solution; because the OP may end up rethinking why they need specific permissions before they find the solution. When I first started working with complex permission issues, I ended up changing my mind and redoing it a dozen times or so before I found a good setup.– HuckleFeb 13, 2012 at 5:51