A USB stick has an fstab entry with the mount point /media/usb. Any ordinary user should be allowed to mount it, but once mounted only the person who mounted it may unmount it again. Which mount option gives exactly that?
LPIC-1 Exam 101-500, objective 104. Devices, Linux filesystems, filesystem hierarchy standard medium
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The options
Correct user
Correct. `user` permits any ordinary user to mount the filesystem, and restricts unmounting to that same user. It also implies noexec, nosuid and nodev unless those are countermanded after it in the option list.
Not correct users
Wrong by one letter. `users` also lets any user mount it, but then lets any user unmount it, which is precisely the difference being tested.
Not correct owner
Wrong. `owner` permits mounting only by the user who owns the device node itself, which is a different and much narrower condition.
Not correct nofail
Wrong. nofail only stops the boot from being held up when the device is absent. It grants nobody any permission.
Why
By default only root may call mount, so a removable-media entry needs an explicit grant in fstab. The pair to keep straight is user (mounter-only unmount) against users (anybody may unmount); group is the analogous grant to members of the device node's group. Because user implies noexec, nosuid and nodev, an entry that genuinely needs executables from the stick must spell out `user,exec` in that order.
Where this comes from
- Cited
- manual page mount(8)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 104 and space the ones you get wrong.
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