Quick Answer
The answer is /etc/passwd, /etc/group, and /etc/shadow. These three files form the core local databases for user and group management in Linux, each serving a distinct but interdependent role: /etc/passwd stores user account details like UID, GID, home directory, and shell; /etc/group defines group names, GIDs, and member lists; and /etc/shadow holds encrypted password hashes along with password aging policies. On the Linux Foundation Certified System Administrator LFCS exam, this concept tests your understanding of how authentication and identity management actually work at the file level, often appearing in questions that ask you to identify which files are consulted by commands like useradd or login. A common trap is assuming /etc/passwd stores passwords—it does not; that is the sole job of /etc/shadow, which is only readable by root. To remember the trio, think of the mnemonic "PGS" for Passwd, Group, Shadow—the three pillars of local user management.
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. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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 THREE files are directly related to user and group management in a Linux system? (Select three.)
/etc/sudoers
Why wrong: Controls sudo access, not user/group management.
/etc/login.defs
Why wrong: Contains default values for user account creation, but not direct user/group data.
/etc/group
Contains group definitions.
/etc/passwd
Contains user account information.
/etc/shadow
Contains encrypted passwords and aging info.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
/etc/group
The files /etc/passwd, /etc/group, and /etc/shadow are the core local databases for user and group management. /etc/passwd stores user account information (username, UID, GID, home directory, shell), /etc/group stores group definitions (group name, GID, member list), and /etc/shadow stores encrypted password hashes and password aging data. These three files are directly consulted by commands like useradd, usermod, groupadd, and login for authentication and identity management.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
/etc/sudoers
Why it's wrong here
Controls sudo access, not user/group management.
/etc/login.defs
Why it's wrong here
Contains default values for user account creation, but not direct user/group data.
/etc/group
Why this is correct
Contains group definitions.
Related concept
Read the scenario before looking for a memorised answer.
/etc/passwd
Why this is correct
Contains user account information.
Related concept
Read the scenario before looking for a memorised answer.
/etc/shadow
Why this is correct
Contains encrypted passwords and aging info.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates may confuse configuration files like /etc/sudoers or /etc/login.defs with the actual user/group database files, but the question specifically asks for files 'directly related to user and group management'—meaning the files that store the user and group records themselves, not files that configure how those records are created or used.
Detailed technical explanation
Under the hood, /etc/passwd and /etc/group are world-readable, while /etc/shadow is readable only by root (or the shadow group) to protect password hashes. When a user logs in, the login process reads /etc/passwd to verify the account exists, then checks /etc/shadow for the password hash and aging info; group membership is resolved from /etc/group. In a real-world scenario, if /etc/shadow is missing or corrupted, users cannot authenticate even if /etc/passwd is intact, because the password hash is unavailable.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
User and Group Management — study guide chapter
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FAQ
User and Group Management — This question tests User and Group Management — Read the scenario before looking for a memorised answer..
The correct answer is: /etc/group — The files /etc/passwd, /etc/group, and /etc/shadow are the core local databases for user and group management. /etc/passwd stores user account information (username, UID, GID, home directory, shell), /etc/group stores group definitions (group name, GID, member list), and /etc/shadow stores encrypted password hashes and password aging data. These three files are directly consulted by commands like useradd, usermod, groupadd, and login for authentication and identity management.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This LFCS practice question is part of Courseiva's free Linux Foundation certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LFCS exam.
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