You might have come across a wide variety of file managers in year GNU/Linux life. But have your ever heard about Midnight Commander? Midnight Commander is a GNU Public Licensed text mode visual file manager that include internal viewer and editor.
Here is an article published in opensource.com that explains about installing and exploring various features of Midnight Commander.
Midnight Commander (MC) is a text-based Command Line Interface (CLI) program. It is particularly useful when a GUI is not available but can also be used as a primary file manager in a terminal session even when you are using a GUI. I use Midnight Commander frequently because I often have need to interact with local and remote Linux computers using the CLI. It can be used with almost any of the common shells and remote terminals through SSH.When used in a terminal session as part of a GUI desktop, Midnight Commander is mouse-aware. Clicking on a file will select it, clicking on a menu item or a function key button will launch that menu or function.