How can I configure spacemacs to always have
linum-mode active in C/C++ buffers (
If it is specific to spacemacs then you can add this line in your
(add-to-hooks 'linum-mode '(c-mode-hook c++-mode-hook))
You could put this in
(global-linum-mode) (with-eval-after-load 'linum (linum-relative-toggle))
The relative number line will be by default.