In the bash shell and in non-Windows versions of the Mongo shell, you can press ctrl-L at any time to get a clean screen with your current line displayed at the top of the screen. This may add some blank lines to your scrollback buffer (the stuff you can see by moving the window's scrollbar) but it never loses data. In the Windows version of the Mongo shell, ctrl-L overwrites display memory with spaces and will destroy not only the scrollback of the Mongo session but any data that had been stored in scrollback memory before you started the Mongo shell. This is kind of rude and makes ctrl-L a lot less useful in Windows. The Windows version of Mongo shell should emulate bash and not destroy scrollback memory.