(setq mode-line-end-spaces "string")
string in the mode-line.
How can I get
string in red there?
You need to create a string with the appropriate face. You do that by attaching a
face text property to the string, giving it value of some face (predefined or defined for the specific purpose - you can look at all the predefined faces with
M-x list-faces-display and pick one from there, or you can define your own face).
E.g. here's a snippet to use a predefined face:
(setq s (copy-sequence "sring")) (put-text-property 0 6 'face 'custom-invalid s) (setq mode-line-end-spaces s)
@NickD provided a good answer: use a face.
OP's comment to Nick's answer says that he'll try to write a function that, given a string, returns a propertized string. Such functions already exist:
propertize does that, and so does
(setq ss (propertize "abcde" 'face '(:foreground "red")))
(setq ss "abcde") (add-face-text-property 0 (length ss) '(:foreground "red") nil ss)