I mounted a folder under /media/datasets, owner and group group are specified as root:

$ ll /media/
drwxrwxrwx 31 root root  4,0K Apr 19 19:55 datasets

Now I want to set the sticky bit to that directory to prevent the users from deleting each others folders, so the rights should look like this:


However when I do

sudo chmod o+t /media/datasets

It says

chmod: changing permissions of ‘/media/datasets’: Operation not permitted

I can execute the command above on folders inside /media/datasets but not on /media/datasets itself. I'm not sure why. Anyone an idea how to fix this?

Not sure if this is important but the datasets folder is located on a synology fileserver (NAS) and is mounted on multiple machines simultaneously.

  • Might the underlying file system of your mounted folder possibly not support sticky bits or Unix permissions in general? Do you know what type it is? – Byte Commander Apr 24 '18 at 12:11
  • Permissions should be fine, since I can set permissions for subfolders . I checked the synology NAS settings. It says "Squash: Map all users to admin: Assigns access privileges to all users of NFS client equivalent to the admin user access privileges on your system." Maybe that is a problem, I will try to change that setting once the NAS is being maintained and report the result here – mcExchange Apr 24 '18 at 12:39
  • Have you tried sudo chmod o+t /media/datasets before mounting the file system here? – pim Apr 24 '18 at 12:56

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