C.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.