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Key Facts: CLF Exam

20Q, 3 hours

Exam Format

PECB

70%

Passing Score

PECB

USD 500 exam-only

Exam Fee

PECB

PECB Certified Linux Foundations (CLF) certification exam evaluates candidates on official PECB domains and standards. Note: this practice set is an English-language MCQ study adaptation.

Sample CLF Practice Questions

Try these sample questions to test your CLF exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which file on a Linux system stores local user account entries, including username, UID, primary GID, home directory, and default login shell?
A./etc/shadow
B./etc/group
C./etc/passwd
D./etc/sudoers
Explanation: /etc/passwd holds one colon-delimited line per local account with the username, an 'x' password placeholder, UID, primary GID, GECOS comment field, home directory, and login shell. It must remain world-readable because many programs map UIDs to names. The actual password hashes live in /etc/shadow.
2Which command creates a new local user account on a Linux system?
A.useradd
B.usermod
C.passwd
D.groupadd
Explanation: useradd creates a new account entry in /etc/passwd and /etc/shadow, and with options such as -m it also creates the home directory. On many distributions the adduser wrapper provides an interactive version of the same task. The new account still needs a password set with passwd before the user can log in with password authentication.
3In the ls -l output '-rwxr-x---', what access does the owning group have to the file?
A.Read, write, and execute
B.Read only
C.Write and execute
D.Read and execute
Explanation: After the leading file-type character, the nine permission characters are three triplets: owner, group, and others. Here the group triplet is 'r-x', meaning group members may read the file and execute it, but not modify it. The final '---' means all other users have no access at all.
4What information is stored in the /etc/shadow file?
A.Group membership lists for all local groups
B.Hashed user passwords together with password-aging fields
C.Filesystems to mount at boot time
D.Per-user environment variable definitions
Explanation: /etc/shadow contains each account's password hash plus aging fields such as last change date, minimum and maximum password age, warning period, and account expiry. Because it holds the hashes, it is readable only by root, which is the entire reason passwords were moved out of the world-readable /etc/passwd.
5Which command switches your current shell session to another user's identity (for example, su - bob)?
A.chown
B.su
C.id
D.whoami
Explanation: su (substitute user) starts a shell as another user; with a dash (su - bob) it also loads that user's login environment. Non-root users must know the target account's password, whereas root can switch to any account without one. It is the classic way to become root when direct root login is disabled.
6What is the purpose of the /etc/sudoers file?
A.It schedules recurring administrative tasks
B.It stores hashed passwords for privileged accounts
C.It lists the network services allowed to run as root
D.It defines which users and groups may run which commands with elevated privileges via sudo
Explanation: /etc/sudoers is the policy file consulted by sudo every time a user requests privilege escalation. Its rules map users or groups to the hosts, target identities, and commands they are permitted to run, optionally without a password. This allows granular delegation of administrative rights without sharing the root password.
7What permissions result from running chmod 750 script.sh?
A.Owner has read/write/execute, group has read/execute, others have no access
B.Owner has read/write/execute, group has write/execute, others have read
C.Everyone has read/execute and only the owner can write
D.Owner has read/write/execute, group has no access, others have read/execute
Explanation: In octal notation each digit is owner, group, then others, with read=4, write=2, execute=1. 7 = 4+2+1 (rwx) for the owner, 5 = 4+1 (r-x) for the group, and 0 = no permissions for others. This is a common setting for scripts only the owner and their team should use.
8Why should administrators edit /etc/sudoers with visudo rather than a plain text editor?
A.visudo encrypts the file so passwords cannot be read
B.visudo is faster because it caches the file in memory
C.visudo validates the syntax on save so a malformed rule cannot lock everyone out of sudo
D.visudo is the only editor root is allowed to run
Explanation: visudo parses the file before writing it and warns (or refuses) if the syntax is invalid, and it also locks the file against simultaneous edits. A syntax error written directly to /etc/sudoers can make sudo unusable for every account, effectively locking administrators out of privilege escalation. Using visudo is therefore a basic operational safety practice.
9What does the command chmod g+w report.txt do?
A.Adds write permission for the owning group, leaving all other permissions unchanged
B.Removes write permission from the owning group
C.Grants write permission to all users on the system
D.Sets the file's owner to the group 'w'
Explanation: Symbolic chmod notation uses u/g/o/a for user, group, others, or all, followed by +, -, or = and the permission letters. g+w adds the write bit to the group triplet only; the owner's and others' permissions are untouched. This targeted style is safer than resetting all permissions with an octal value.
10With a umask of 022, what permissions does a newly created regular file receive by default?
A.755
B.600
C.644
D.777
Explanation: Regular files start from a base of 666 (no execute bit by default) and the umask bits are subtracted. 666 - 022 = 644, giving the owner read/write and group and others read only. Directories use a base of 777, so the same umask yields 755 for new directories.

About the CLF Exam

The PECB Certified Linux Foundations (CLF) certification evaluates professional competence in governance, implementation, auditing, and management according to PECB standards.

Questions

20 scored questions

Time Limit

3 hours

Passing Score

70%

Exam Fee

USD 500 exam-only (PECB (Professional Evaluation and Certification Board))

CLF Exam Content Outline

~25%

Linux Fundamentals & Command Line Operations

Linux architecture, bash shell commands, text processing (grep, sed, awk), pipe redirection, and environment variables.

~20%

User Administration and Permission Management

Managing users and groups, POSIX permissions (chmod, chown), umask, SUID/SGID, sticky bit, and sudo privilege escalation.

~20%

File System Hierarchy and Storage Management

File system layout (FHS), partitioning (fdisk, parted), LVM configuration, mounting file systems, and disk quota management.

~20%

Process Management and System Services

Managing processes (ps, top, kill, systemctl), systemd service management, cron scheduling, and system logging (journalctl, syslog).

~15%

Network Configuration and Basic Linux Security

IP configuration (ip, netstat), SSH hardening, iptables/nftables firewall rules, SELinux/AppArmor basics, and system patching.

How to Pass the CLF Exam

What You Need to Know

  • Passing score: 70%
  • Exam length: 20 questions
  • Time limit: 3 hours
  • Exam fee: USD 500 exam-only

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

CLF Study Tips from Top Performers

1Review the official PECB candidate handbook
2Practice scenario-based questions across all domains
3Pace yourself to answer all questions within the time limit

Frequently Asked Questions

What is the format of the PECB Linux Foundations exam?

The official exam consists of 20 questions over 3 hours. This practice set provides 100 English-language MCQs as a study aid.

Is this practice test free?

Yes, 100% free with detailed explanations.