LPIC-1 Devices, Filesystems and FHS Practice Question
A technician is troubleshooting a server whose /var partition is reported as full by applications, but df -h shows the filesystem at only 40 percent usage. The technician suspects deleted files are still held open by running processes. Which command best identifies the process holding a deleted file open on that filesystem?
⚠ Common exam trap
The trap here is trusting du output to match df, when unlinked-but-open files are invisible to du yet still consume blocks counted by df.
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
✓
lsof +L1
When a file is unlinked while a process still holds it open, the blocks remain allocated but the name disappears from the directory tree, so df shows usage that du cannot account for. lsof with the +L1 filter enumerates files whose link count has dropped below one, exposing the process responsible and allowing the administrator to restart it and reclaim space.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
lsof +L1
Why this is correct
The +L1 option to lsof lists files with a link count less than one, which is exactly the state of a file that has been unlinked but is still referenced by an open file descriptor. This reveals the process name and PID holding the space, directly addressing the suspected cause.
- ✗
fuser -m /var
Why it's wrong here
fuser -m lists processes using any file on the specified mount point, but it does not distinguish deleted files from active ones and produces a bare PID list. It may show many unrelated processes and does not confirm which one holds the unlinked file, making it a weaker diagnostic than a link-count filter.
- ✗
df -i /var
Why it's wrong here
The -i option reports inode usage rather than block usage. It would reveal whether the filesystem has run out of inodes, which is a different failure mode, but it cannot show which process holds a deleted file open. The applications reported a space problem, not an inode exhaustion problem.
- ✗
du -sh /var
Why it's wrong here
du walks directory entries and sums apparent file sizes. Because a deleted file no longer appears in any directory, du cannot see the space it occupies, which is why du and df disagree in this scenario. Running it would simply confirm the undercount rather than identify the holding process.
Go deeper
Related to this question
About these practice questions
One of 402 original LPIC-1 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. 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 LPI exam blueprint
This LPIC-1 practice question is part of Courseiva's free LPI 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 LPIC-1 exam.