The minibuffer is an Emacs buffer (albeit a peculiar one), and the usual Emacs commands are available for editing the text of an argument you are entering.
Since RET in the minibuffer is defined to exit the minibuffer, you can't use it to insert a newline in the minibuffer. To do that, type C-o or C-q C-j. (Recall that a newline is really the character control-J.)
The minibuffer has its own window which always has space on the screen but acts as if it were not there when the minibuffer is not in use. When the minibuffer is in use, its window is just like the others; you can switch to another window with C-x o, edit text in other windows and perhaps even visit more files, before returning to the minibuffer to submit the argument. You can kill text in another window, return to the minibuffer window, and then yank the text to use it in the argument. See section Multiple Windows.
There are some restrictions on the use of the minibuffer window, however. You cannot switch buffers in it--the minibuffer and its window are permanently attached. Also, you cannot split or kill the minibuffer window. But you can make it taller in the normal fashion with C-x ^. If you enable Resize-Minibuffer mode, then the minibuffer window expands vertically as necessary to hold the text that you put in the minibuffer. Use M-x resize-minibuffer-mode to enable or disable this minor mode (see section Minor Modes).
Scrolling works specially in the minibuffer window. When the
minibuffer is just one line high, and it contains a long line of text
that won't fit on the screen, scrolling automatically maintains an
overlap of a certain number of characters from one continuation line to
the next. The variable
minibuffer-scroll-overlap specifies how
many characters of overlap; the default is 20.
If while in the minibuffer you issue a command that displays help text of any sort in another window, you can use the C-M-v command while in the minibuffer to scroll the help text. This lasts until you exit the minibuffer. This feature is especially useful if a completing minibuffer gives you a list of possible completions. See section Using Other Windows.
Emacs normally disallows most commands that use the minibuffer while
the minibuffer is active. This rule is to prevent recursive minibuffers
from confusing novice users. If you want to be able to use such
commands in the minibuffer, set the variable
enable-recursive-minibuffers to a non-
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