LFCS Question #82: Real Exam Question with Answer & Explanation

The correct answer is B: lsof. The lsof command is used to list open files and the processes using them, which is essential for identifying why a device cannot be unmounted because it is busy.

Submitted by thandi_sa· Apr 18, 2026Storage Management

Question

When trying to unmount a device it is reported as being busy. Which of the following commands could be used to determine which process is causing this?

Options

Adebug
Blsof
Cnessus
Dstrace
Etraceroute

Explanation

The lsof command is used to list open files and the processes using them, which is essential for identifying why a device cannot be unmounted because it is busy.

Common mistakes.

A. debug is a general term for troubleshooting and not a specific command to list open files.
C. nessus is a vulnerability scanner, not a tool for checking open files.
D. strace is used to trace system calls and signals, not to list open files.
E. traceroute is used to trace the path of network packets, not to identify processes holding files open.

Concept tested. Identifying processes holding open files

Reference. https://man7.org/linux/man-pages/man8/lsof.8.html

Topics

#lsof#unmounting#file systems#process identification

Community Discussion

No community discussion yet for this question.

Full LFCS Practice Browse All LFCS Questions