LFCS Essential Commands Practice Question
Exhibit
$ df -h Filesystem Size Used Avail Use% Mounted on /dev/sda1 50G 45G 5.4G 90% / /dev/sdb1 100G 20G 80G 20% /data
Refer to the exhibit. The administrator receives alerts that the root filesystem is almost full. Which command could free up space by removing old log files?
⚠ Common exam trap
Linux Foundation often tests the distinction between commands that merely display disk usage (like `du`) versus those that actually remove files, and the danger of using `rm -rf` with wildcards on system directories like /var/log.
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
✓
find /var/log -name '*.log' -mtime +30 -delete
The `find` command with `-name '*.log'` targets log files, `-mtime +30` selects files modified more than 30 days ago, and `-delete` removes them. This safely frees space by purging only old logs, preserving recent logs needed for troubleshooting.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
find /var/log -name '*.log' -mtime +30 -delete
Why this is correct
Removes old log files safely.
- ✗
truncate -s 0 /var/log/syslog
Why it's wrong here
Only truncates one file, not all old logs.
- ✗
rm -rf /var/log/*
Why it's wrong here
Removes all log files, including current ones, potentially causing data loss.
- ✗
du -sh /var/log
Why it's wrong here
Shows disk usage but does not free space.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.