Getting the list of open files

We know that there can be millions of files available in a system, which can be binary files, text files, directories, and so on. When a file is not in use, they are just available on a storage device as 0 and 1. To view or process a file, it needs to be opened. An application that is executing may open multiple files. Knowing what files are opened by a running application is very useful. To know the list of opened files, the lsof command is used.

Executing the following command gives the list of all opened files:

$ lsof

This gives a huge output of all the opened files.

Knowing the files opened by a specific application

To know the list of files opened by a specific application, first get the Process ID (PID) of the running application:

$ pidof application_name

For example, let's run cat without any parameter:

$ cat

In another terminal, run the following commands:

$ pidof cat
15913
$ lsof -p 15913

Alternatively, we can directly write the following command:

$ lsof...