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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
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  • Don't forget gui=1000. Also, what is the ownership/rights to /var/www. It should be owned by root.
    – skub
    Aug 8, 2011 at 12:57
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    @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, 2011 at 21:14
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    Your mount source is "dev"?? Aug 8, 2011 at 21:51
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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, 2011 at 23:16
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    I've been messing around with this problem in vbox for a while now too. From what I've gathered, the correct solution (to the question you aren't asking) is to add your user into the vboxsf group, and then it doesn't matter who the owner of the files are - you will have permission to edit them. alcobrov.blogspot.com/2012/06/… Aug 23, 2014 at 0:00

2 Answers 2

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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=filePermissions,gid=ownerGroupID,uid=ownerID /device /mountpoint

For example mounting 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=filePermissions,gid=ownerGroupID,uid=ownerUserID

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.

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  • I was able to use the uid/gid option on ext4. Dec 9, 2015 at 9:45
  • This doesn't seem to work with mount --bind , i'm using a btrfs file system Mar 18, 2017 at 16:48
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    Shouldn't the umask be umask=0077 instead of umask=0022 to give permission only owner to read or write? It seems that umask=0022 will give read permissions to others if I am reading it correctly. I want that only the user who mount the disk should have read or write permission. Jan 9, 2019 at 14:00
  • uid=1000,gid=1000 do not work on btfs filesystem on kde with debian 11 on kernel 5.10.0-8-amd64. The error says: mount: /store1: wrong fs type, bad option, bad superblock on /dev/sda1, missing codepage or helper program, orother error. The complete line from /etc/fstab is: "UUID=755d31e9-4ed0-4a41-9821-dd777f12e3dd /store1 btrfs uid=1000,gid=1000,noatime,nodiratime 0"
    – piotao
    Sep 11, 2021 at 14:49
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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. Apr 29, 2013 at 15:16
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    -o unfortunately doesn't work for ext4, as explained in the answer by @wowpatrick.
    – js.
    Aug 18, 2014 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, 2015 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, 2015 at 7:40
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    bindfs allows you to mount a directory with different user and group ownership - this can be helpful to avoid chown'ing all the files - although I found this question hoping to find a more elegant approach than bindfs. Apr 14, 2020 at 13:05

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