Flymake is an Emacs minor mode.
To use Flymake, you must first activate flymake-mode
by using the flymake-mode function.
Instead of manually activating flymake-mode, you
can configure Flymake to automatically enable
flymake-mode upon opening any file for which syntax
check is possible. To do so, place the following line in
.emacs:
(add-hook 'find-file-hook 'flymake-find-file-hook)