In the situation where you want to open multiple files in vim using splits (or vsplits), here's what I did before:
vim <file1> :split <file2> :split <file3>
And so on...
Here's the tip:
vim -o <file1> <file2> ... <fileN>
This command opens n files into horizontal splits. If you prefer vertical splits, use -O instead.
Suppose you want to get to Line 15 of every single split:
In fact, in general:
:windo execute [your command]
But wait, there's more! Say now that you're done editing the files and you want to save all of them at once:
Yes, it is that simple. The usual :w plus a.
I bet you can guess how to close/quit all files at one go.
(Still getting used to markdown. Pardon me)
(This tip is similar to https://coderwall.com/p/n1abyq. Just giving credits to Alexander, and that I learned about -p from his tip)