--- 
canonical: 'https://mwop.net/blog/38-Whats-keeping-that-device-in-use.html'
title: "What's keeping that device in use?"
author: "[Matthew Weier O'Phinney](https://mwop.net)"
created: '2004-09-11T21:27:11-05:00'
updated: '2004-09-20T13:59:20-05:00'
tags:
  - linux
  - personal

---
Ever wonder what's keeping that device in use so you can't unmount it? It's
happened to me a few times. The tool to discover this information? `lsof`.

Basically, you type something like: `lsof /mnt/cdrom` and it gives you a `ps`-style
output detailing the PID and process of the processes that are using the cdrom.
You can then go and manually stop those programs, or kill them yourself.