How can you determine the files that the currently running application in Linux is working with?

In Linux, to identify files that a running application is currently using, you can use the lsof (list open files) command. It shows all open files of processes.

For example, to see files opened by the process with PID 1234, run:

lsof -p 1234

You can also use the /proc directory:

ls -l /proc/1234/fd/

Here, fd are the file descriptors of the process, which are links to open files.

Thus, lsof and viewing /proc/[pid]/fd allow you to determine which files the application is using.