Why does vim add ^J to the end of my macros?

Question

I wrote short macro that helps me grep for the word under the cursor. Here it is in my .vimrc:

let @a=":! git grep ^R^W^M"

However, when I open vim and run :reg a, I see the following:

"a   :! git grep ^R^W^M^J

You can see an ^J has been added to the macro.

If I remove the ^M in my script, then the ^J disappears also.

It seems the ^J acts similar to ^M. So, it's like I have two ^M. This isn't what I want, because I can't see the result of my command. The window just flashes before I can read it.

I have gotten my script to work by pasting and then copying it. The problem only arises when I try to load it using my .vimrc.

Answer 1

For whatever weird reason, it works fine if you replace the ^M^J with ^J:

:let @a=":! git grep \<c-r>\<c-w>\<c-j>"
:reg a
"a   :! git grep ^R^W^J

And @a works as expected.

(I'm using the \<...> notation since it is easier to copy paste.)

---

Technically, ^M is the carriage return and ^J is the newline. I'm not sure how the difference matters in this case.