How can I mount a device with specific user rights on start up? I still have some problems figuring it out. I would like to mount the divide with uid=1000 and gid=1000. My current entry to the /etc/fstab/ file looks like this:

dev /var/www vboxsf rw, suid, dev, exec, auto, nouser, async, uid=1000
  • Don't forget gui=1000. Also, what is the ownership/rights to /var/www. It should be owned by root. – skub Aug 8 '11 at 12:57
  • @skub: The owner of /var/www/ is root. dev /var/www vboxsf rw, suid, dev, exec, auto, nouser, async, uid=1000 gui=1000 didin't work so well (Ubuntu removed the entry after a failed restart). – wowpatrick Aug 8 '11 at 21:14
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    Your mount source is "dev"?? – James T Snell Aug 8 '11 at 21:51
  • @wowpatrick - your mount device should be something like /dev/sda1 it should not be 'dev'. – skub Aug 8 '11 at 22:53
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    @skub: It's a VirtualBox shared folder, so /dev is is right. I figured it out by now, sudo mount -t vboxsf -o umask=0022,gid=33,uid=33 dev /var/www works just fine. – wowpatrick Aug 8 '11 at 23:16
up vote 99 down vote accepted

To mount a device with certain rights, you can use the -o Option directive while mounting the device. To mount the device you described, run:

 mount -t deviceFileFormat -o umask=filePermissons,gid=ownerGroupID,uid=ownerID /device /mountpoint

For example mountig a VirtualBox shared folder to /var/www with www-data as owner would look like this:

mount -t vboxsf -o umask=0022,gid=33,uid=33 dev /var/www

If you want to mount the device on startup, you can add the following entry to your /etc/fstab file:

 /device /mountpoint deviceFileFormat umask=filePermissons,gid=ownerGroupID,uid=ownerID

Again, with the same example the entry to the /etc/fstab file would look like this:

dev /var/www vboxsf umask=0022,gid=33,uid=33

For filesystems that does not support mounting as a specific user (like ext4) the above will give the error

Unrecognized mount option "uid=33" or missing value

to change the owner of an ext4 mount simply run

chown username /mountpoint

after it has been mounted.

  • I was able to use the uid/gid option on ext4. – CMCDragonkai Dec 9 '15 at 9:45
  • This doesn't seem to work with mount --bind , i'm using a btrfs file system – meffect Mar 18 '17 at 16:48

For a file-system like ext3 or ext4, after doing

    chown -R username:group /mountpoint

to change the owner of the currently existing files you can set the group id bit to have new files created with the specific group (doesn't work for the user id under Linux):

    find /mountpoint -type d -exec chmod g+ws {} \;

The Wikipedia entry on setuid and setgid is quite informative, see the section on directories.

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    Changing the ownership of all the files on the device is very invasive. Since there is a -o option for mount, it is the better way. – Limited Atonement Apr 29 '13 at 15:16
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    -o unfortunately doesn't work for ext4, as explained in the answer by @wowpatrick. – js. Aug 18 '14 at 20:55
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    chowning the contents of the mounted drive to some other user is ridiculous. You have no idea what you might break for any applications on that drive. It may be fine if all of the contents belong to your user, but this is a very big no-no... – carlspring Apr 12 '15 at 1:56
  • The device in question is /dev/www, it is easy to control which applications have access to it (probably only a WWW server, which you can turn off during the operation). Even if the app using it is still running, it will keep running, since that is the point of the operation. – js. Apr 13 '15 at 7:40

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