Install lsof by entering the following commands in the terminal:
sudo apt update sudo apt install lsof
Description:
Utility to list open files
Lsof is a Unix-specific diagnostic tool. Its name stands for LiSt Open Files, and it does just that. It lists information about any files that are open, by processes currently running on the system.
Homepage: http://people.freebsd.org/~abe/
Version: 4.89+dfsg-0.1
Section: utils