the truncation is a poor example.

- it creates the file if it does not exist, not merely truncate. as a tutorial kind of blog post this incomplete description matters IMO.

- it would work the same without the colon (similar for default variable assignment examples). we generally strive not to have "extra" things, like useless use of cat.

- educationally it's useful to demonstrate that redirection, like parameter expansion, works before the command executes (the null command in this case), but the article doesn't explain that at all!

otherwise i <3 this article. some uses of colon i had never thought of or seen before. like file truncation, not sure i'd use them but it was cool to see them.