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LFCS · Question #300

To prevent a specific user from scheduling tasks with at, which of the following should the administrator do?

The correct answer is C. Add the specific user to /etc/at.deny file. To prevent a specific user from scheduling tasks using the at command, their username should be added to the /etc/at.deny file.

Submitted by lukas.cz· Apr 18, 2026User and Group Management

Question

To prevent a specific user from scheduling tasks with at, which of the following should the administrator do?

Options

  • AAdd the specific user to /etc/at.allow file.
  • BAdd the specific user to [deny] section in the /etc/atd.conf file.
  • CAdd the specific user to /etc/at.deny file.
  • DAdd the specific user to nojobs group.
  • ERun the following: atd --deny [user].

How the community answered

(32 responses)
  • C
    91% (29)
  • D
    3% (1)
  • E
    6% (2)

Why each option

To prevent a specific user from scheduling tasks using the `at` command, their username should be added to the `/etc/at.deny` file.

AAdd the specific user to /etc/at.allow file.

Adding a user to `/etc/at.allow` would *grant* them permission to use `at`, not deny them, assuming `/etc/at.allow` exists and takes precedence.

BAdd the specific user to [deny] section in the /etc/atd.conf file.

There is no standard `[deny]` section in `/etc/atd.conf` for directly denying users access to `at` jobs; user access is controlled by `at.allow` and `at.deny` files.

CAdd the specific user to /etc/at.deny file.Correct

The `at` and `batch` commands consult `/etc/at.allow` and `/etc/at.deny` to control user access. If `/etc/at.allow` does not exist (a common scenario), then any user listed in `/etc/at.deny` is explicitly prevented from scheduling `at` jobs, effectively denying them access.

DAdd the specific user to nojobs group.

There is no standard `nojobs` group that specifically controls `at` access; `at` access is managed via the `at.allow` and `at.deny` configuration files.

ERun the following: atd --deny [user].

`atd` is the daemon that runs `at` jobs, and `--deny` is not a standard option for `atd` to deny a specific user's scheduling capability; user access is managed through configuration files.

Concept tested: `at` command user access control

Source: https://manpages.ubuntu.com/manpages/jammy/en/man1/at.1.html

Topics

#at command#Job scheduling#User access control#Configuration files

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