SSCP Systems and Application Security Practice Question
In Linux, which command is used to change file permissions to restrict access so that only the owner can read and write, and the group and others have no access?
⚠ Common exam trap
SSCP often tests the confusion between chmod (change permissions), chown (change ownership), and umask (set default creation mask) — candidates pick umask or chown when the question asks to modify an existing file's permissions.
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
✓
chmod 600 file.txt
chmod 600 file.txt sets permissions so the owner has read and write (6 = rw-), while group and others have no permissions (0 = ---). This matches the requirement that only the owner can read and write and no one else has access. The numeric (octal) mode 600 is the standard way to express owner rw, group none, others none.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
chmod 600 file.txt
Why this is correct
chmod 600 file.txt sets the permission bits to rw-------, giving the owner read and write while group and others receive none. The octal 6 encodes read (4) plus write (2) for the owner, and the two trailing zeros deny all group and other access, satisfying the stem's restriction requirement.
- ✗
chown 600 file.txt
Why it's wrong here
chown changes file ownership (user and group), not permission bits, so it cannot set read/write-only-for-owner. It is the right command when transferring a file to a different user or group, for example reassigning ownership after a staff change.
- ✗
umask 077 file.txt
Why it's wrong here
umask sets the default permission mask for newly created files; it does not alter an existing file's mode, and passing a filename is invalid syntax. It is correctly used in shell profiles to control permissions on future file creation.
- ✗
setfacl -m u::rw file.txt
Why it's wrong here
setfacl with only a user entry modifies the access control list, leaving group and other permissions untouched rather than removing them. It is correct when granting an additional named user access beyond the standard owner/group/other model.
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About these practice questions
Courseiva writes every SSCP question from scratch — 971 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISC2 exam blueprint
This SSCP practice question is part of Courseiva's free ISC2 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 SSCP exam.