- A
id -Gn username
Correct. `id -Gn username` displays all group names (primary and supplementary) for the user.
- B
cat /etc/passwd | grep username
Why wrong: Incorrect. This command shows the user's line from /etc/passwd, which includes the primary group ID but not supplementary groups. It does not display group membership.
- C
id -g username
Why wrong: Incorrect. `id -g username` shows only the primary group ID (numeric), not all groups.
- D
groups username
Correct. `groups username` lists all group names the user belongs to, including both primary and supplementary groups.
- E
grep username /etc/group
Why wrong: Incorrect. `grep username /etc/group` shows only groups where the user is explicitly listed. It misses the primary group if it is not listed in /etc/group.
LFCS id -Gn Practice Question
This LFCS practice question tests your understanding of user and group management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: id -Gn. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which TWO commands can be used to display the group membership of a user? (Choose two.)
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
id -Gn username
Options A and D are correct. The `id -Gn` command displays all group names (primary and supplementary) for a user. The `groups` command also lists all group memberships for a user. Option B shows the user's entry in /etc/passwd, which includes primary group ID but not supplementary groups. Option C shows only the primary group ID (numeric). Option E lists groups where the user is explicitly listed in /etc/group, but it misses the primary group if not listed there.
Key principle: id -Gn
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
id -Gn username
Why this is correct
Correct. `id -Gn username` displays all group names (primary and supplementary) for the user.
Related concept
id -Gn
- ✗
cat /etc/passwd | grep username
Why it's wrong here
Incorrect. This command shows the user's line from /etc/passwd, which includes the primary group ID but not supplementary groups. It does not display group membership.
- ✗
id -g username
Why it's wrong here
Incorrect. `id -g username` shows only the primary group ID (numeric), not all groups.
- ✓
groups username
Why this is correct
Correct. `groups username` lists all group names the user belongs to, including both primary and supplementary groups.
Related concept
id -Gn
- ✗
grep username /etc/group
Why it's wrong here
Incorrect. `grep username /etc/group` shows only groups where the user is explicitly listed. It misses the primary group if it is not listed in /etc/group.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common trap is confusing `id -g` (primary group only) with `id -Gn` (all group names). Also, `grep username /etc/group` does not show primary group membership if the primary group is listed only in /etc/passwd.
Trap categories for this question
Command / output trap
Incorrect. This command shows the user's line from /etc/passwd, which includes the primary group ID but not supplementary groups. It does not display group membership.
Detailed technical explanation
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- id -Gn
- groups
- id -g
- Primary vs Supplementary Groups
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
id -Gn
Real-world example
How this comes up in practice
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. id -Gn Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Review id -Gn, then practise related LFCS questions on the same topic to reinforce the concept.
- →
User and Group Management — study guide chapter
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FAQ
Questions learners often ask
What does this LFCS question test?
User and Group Management — This question tests User and Group Management — id -Gn.
What is the correct answer to this question?
The correct answer is: id -Gn username — Options A and D are correct. The `id -Gn` command displays all group names (primary and supplementary) for a user. The `groups` command also lists all group memberships for a user. Option B shows the user's entry in /etc/passwd, which includes primary group ID but not supplementary groups. Option C shows only the primary group ID (numeric). Option E lists groups where the user is explicitly listed in /etc/group, but it misses the primary group if not listed there.
What should I do if I get this LFCS question wrong?
Review id -Gn, then practise related LFCS questions on the same topic to reinforce the concept.
What is the key concept behind this question?
id -Gn
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Last reviewed: Jun 24, 2026
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