Remove everything but the first column in VIM

Question

I have a text file and I want to remove every word except the first word on every line and I have no idea how to do this.

So, if I have:

one two three
four five
six

I want to remain with:

one
four
six

Got any ideas?

Answer 1

If the lines don't start with whitespace, you could replace ' .*' (which matches everything after the first word) with an empty string:

:%s/ .*//g