read-no-blanks-input

read-no-blanks-input is a built-in function in `C source code'.

(read-no-blanks-input PROMPT &optional INITIAL INHERIT-INPUT-METHOD)

Read a string from the terminal, not allowing blanks.
Prompt with PROMPT. Whitespace terminates the input. If INITIAL is
non-nil, it should be a string, which is used as initial input, with
point positioned at the end, so that SPACE will accept the input.
(Actually, INITIAL can also be a cons of a string and an integer.
Such values are treated as in `read-from-minibuffer', but are normally
not useful in this function.)
Third arg INHERIT-INPUT-METHOD, if non-nil, means the minibuffer inherits
the current input method and the setting of`enable-multibyte-characters'.