emacs/replace-with-newline

replace a character with a newline in Emacs

M-x replace-string RET ; RET C-q C-j.

    C-q for quoted-insert,

    C-j is a newline.

How to put a newline into the minibuffer

    C-o
    C-q C-j
    C-q 12 (12 is the octal value of newline)
    C-x o to the main window, kill a newline with C-k, then C-x o back to the minibuffer, yank it with C-y