easyMultiple Choice
XK0-006 Practice Question: A junior administrator accidentally modified the…
A junior administrator accidentally modified the /etc/sudoers file and now users report not being able to use sudo. Which command should be used to safely edit the sudoers file?
⚠ Common exam trap
Many candidates think any method that writes to the file (like `echo` or `chmod`) can fix the issue, but only `visudo` provides the syntax validation and locking necessary to safely edit the sudoers file without breaking sudo.
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
✓
visudo
The `visudo` command is the correct and safe way to edit the `/etc/sudoers` file because it locks the file against concurrent edits, performs syntax validation before saving, and prevents saving a malformed configuration that could break sudo entirely. This ensures that even if the administrator makes a mistake, the original valid file is preserved, avoiding the exact scenario described where users lose sudo access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
visudo
Why this is correct
Editing /etc/sudoers directly risks a syntax error that locks out sudo entirely. visudo validates the file's syntax before saving and writes atomically, so a malformed edit is rejected rather than committed, satisfying the requirement to edit safely.
- ✗
chmod 400 /etc/sudoers
Why it's wrong here
chmod alters file permissions; it cannot repair malformed sudoers syntax, so sudo stays broken. Editing permissions does not validate entries. The tempting fix is locking the file down after a bad edit, but recovery requires visudo, which parses the file and refuses to save invalid syntax, preventing lockout.
- ✗
echo 'user ALL=(ALL) ALL' >> /etc/sudoers
Why it's wrong here
Appending with >> bypasses visudo's syntax and lock checks, so a malformed line can break sudo for every user. It is tempting because it adds a grant quickly, but the scenario requires repairing a corrupted sudoers file, which visudo alone validates and edits safely.
- ✗
usermod -aG wheel user
Why it's wrong here
Adding the user to the wheel group grants sudo rights but does not repair the malformed /etc/sudoers syntax that is blocking sudo. Group membership is the right fix when a valid sudoers file simply lacks an entry for that user.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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