The command-line option ‘-batch’ causes Emacs to run noninteractively. In this mode, Emacs does not read commands from the terminal, it does not alter the terminal modes, and it does not expect to be outputting to an erasable screen. The idea is that you specify Lisp programs to run; when they are finished, Emacs should exit. The way to specify the programs to run is with ‘-l file’, which loads the library named file, or ‘-f function’, which calls function with no arguments, or ‘--eval form’.
Any Lisp program output that would normally go to the echo area,
message, or using
prin1, etc., with
t as the stream, goes instead to Emacs’s standard descriptors
when in batch mode:
message writes to the standard error
prin1 and other print functions write to the
standard output. Similarly, input that would normally come from the
minibuffer is read from the standard input descriptor. Thus, Emacs
behaves much like a noninteractive application program. (The echo
area output that Emacs itself normally generates, such as command
echoing, is suppressed entirely.)
Non-ASCII text written to the standard output or error descriptors is
by default encoded using
locale-coding-system (see Locales)
if it is non-
nil; this can be overridden by binding
coding-system-for-write to a coding system of you choice
(see Explicit Encoding).
This variable is non-
nil when Emacs is running in batch mode.