How to yank a particular line without moving the cursor in vim?

If the cursor is already on line 12, then a simple

:4y
P

does it for me.

How about this: Cursor is on line 11, you're in "vi" mode.

:4co.<return>

You can apparently also do it with a pattern:

:/^Yank/co.<return>

You could use "mo" (move) instead of "co" (copy) to just move the line, instead of yank and put.

Try this:

:4,4y  
P