"Device is busy" is a common error message that you may encounter when trying to unmount a device on a Linux system. This error occurs when the system detects that a file or process is still actively using the device

and therefore it cannot be unmounted at that time.

In this article

I will explain why this error occurs

how to identify the process that is using the device

and different ways to resolve the issue.

1. Why does the "Device is busy" error occur?

When you attempt to unmount a device

the operating system first checks if any files or processes are currently using the device. If it finds any active connections or open files

it considers the device to be busy and prevents unmounting to avoid data loss or corruption.

2. Identifying the process using the device

To identify the process that is causing the "Device is busy" error

you can use the `lsof` command. lsof stands for “list open files” and it provides information about files and processes currently running on the system.

To use the `lsof` command

open a terminal and type the following command:

```shell

$ lsof | grep /mount/point

```

Replace /mount/point with the actual mount point of the device you are trying to unmount. This command will display all the processes that have an active file handle on that device.

3. Resolving the "Device is busy" error

a) Closing open files: If the device is busy because of open files

consider closing them. Identify which files are open using the `lsof` command as described above. Once you have identified the files

close them by using the appropriate application or command. Once all files are closed

you should be able to unmount the device without any issues.

b) Killing processes: In some cases

a process might be actively using the files on the device

and closing the files is not sufficient. In such cases

you can kill the processes that are using the device.

To kill a process

you need to know its process ID (PID) which you can find using the `lsof` command. Once you have the PID

use the `kill` command with the PID to terminate the process. For example:

```shell

$ kill PID

```

Replace PID with the actual PID of the process you want to kill. Once the process is terminated

you should be able to unmount the device.

c) Unmount forcibly: If the above methods do not work or are not feasible

you can forcefully unmount the device. This method should be used with caution as it can potentially cause data loss or corruption. To forcibly unmount a device

use the following command:

```shell

$ umount -f /mount/point

```

Replace /mount/point with the actual mount point of the device. Note that forcibly unmounting may result in the loss of unsaved data or cause system instability.

4. Conclusion

The "Device is busy" error occurs when the system detects that a file or process is actively using the device. To resolve this issue

you can close open files

kill processes using the device

or forcibly unmount the device. It is important to be cautious while forcibly unmounting to avoid data loss or system instability. By following the steps outlined in this article

you should be able to successfully resolve the "Device is busy" error and unmount the device.