GNU Emacs Manual
AE.3 Command Argument Example
Here is an example of using Emacs with arguments and options. It
assumes you have a Lisp program file called `hack-c.el' which, when
loaded, performs some useful operation on the current buffer, expected
to be a C program.
emacs -batch foo.c -l hack-c -f save-buffer >& log
This says to visit `foo.c', load `hack-c.el' (which makes
changes in the visited file), save `foo.c' (note that
save-buffer is the function that C-x C-s is bound to), and
then exit back to the shell (because of `-batch'). `-batch'
also guarantees there will be no problem redirecting output to
`log', because Emacs will not assume that it has a display terminal
to work with.