Here is how you can check if Files and Folders exist using PowerShell. PowerShell has a built-in Test-Path cmdlet that you can run as a script file.

You can view a Text file in Command Prompt or PowerShell in Windows 11/10. You can view the entire content of TXT, a specific line, etc.

Windows Search doesn't look particularly effective. But with a little knowledge and tweaking, you can find almost anything you're looking for.

If you want to know what files a process is using, then yes, lsof is your friend. If you want to know what processes are using a file, you can use lsof + grep, or you can use fuser.