LPIC-1 GNU and Unix Commands Practice Question
Exhibit
$ cat /etc/at.allow root user1 $ cat /etc/at.deny user2 user3
Refer to the exhibit. Which users are allowed to use the 'at' command?
⚠ Common exam trap
The key trap is that when /etc/at.allow exists, it takes precedence over /etc/at.deny entirely. Only users listed in the allow file (plus root) are permitted, regardless of any deny file. Many candidates mistakenly think that all users not in a deny list are allowed.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
root and user1
The 'at' command is controlled by the /etc/at.allow and /etc/at.deny files. If /etc/at.allow exists, only users listed in it (plus root) can use 'at'. The exhibit shows /etc/at.allow contains 'root' and 'user1', so both are allowed. If /etc/at.allow does not exist, /etc/at.deny is checked; but here the allow file takes precedence.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
No one
Why it's wrong here
root and user1 are allowed.
- ✓
root and user1
Why this is correct
If at.allow exists, only users listed in it can use at.
- ✗
All users except user2 and user3
Why it's wrong here
at.allow overrides at.deny.
- ✗
Only root
Why it's wrong here
user1 is also allowed.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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