How can a specific user be prevented from scheduling tasks with at?

Question

Options

• ABy adding the specific user to the /etc/at.allow file.
• BBy adding the specific user to the [deny] section in the /etc/atd.conf file.
• CBy adding the specific user to the nojobs group.
• DBy adding the specific user to the /etc/at.deny file.
• EBy executing the atd --deny [user] command.

• A
  9% (3)
• B
  6% (2)
• C
  3% (1)
• D
  82% (28)

Explanation

Adding a user to /etc/at.deny explicitly blocks that user from submitting jobs via the at command - when the at daemon checks permissions, any username listed in this file is refused scheduling rights while all other users remain unaffected.

Why the distractors are wrong:

• A is the opposite: /etc/at.allow is a whitelist - only users listed there can use at, so adding someone to it grants access, not denies it.
• B is fabricated: /etc/atd.conf with a [deny] section does not exist; at access control is handled entirely through the two flat files, not a config file with sections.
• C is fictional: there is no nojobs group in Linux that interacts with the at subsystem.
• E is invalid syntax: atd is the daemon process and accepts no --deny flag; it has no runtime user-management interface.

Memory tip: Think of the two files as a bouncer's lists - at.allow is the VIP guest list (only listed names get in), and at.deny is the banned list (listed names are turned away). To block one specific person without restricting everyone else, put them on the banned list (at.deny).

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