This is pretty simple to do. It’s also very usable if you just want to compare 2 files or different sections on the same file. Here’s what you do while in vi or vim.
Split screen horizontally
The above code will split vi horizontally like the screenshot below. You can also supply an optional filename. If you do, it’ll open new file on the second window.
Split screen vertically
Unsurprisingly, the above code will split vi vertically like the screenshot below. Just like :split command above, :vsplit will also take optional filename that if supplied will open the named file on the new screen instead.
Navigating between screens
Navigating between split-ed screens is pretty easy in vi. Just type ctrl-w ctrl-w (that is twice ctrl-w) to jump between screens. You can also use ctrl-w then arrow key to move to different screens. This is useful if you split screens into more than 2 like below.
There you have it. And as always, I welcome comments / questions / critics that will help me and other readers understand better.