Batch export of org-mode files from the command line - emacs

Question

Assume that I have in a certain directory several org-mode files: foo1.org, foo2.org, etc. I would like to have a script (maybe a makefile) that I could invoke something like
$ generate-pdfs
and foo1.pdf, foo2.pdf, etc. will be generated.
I thought that something like emacs --batch --eval <MAGIC> is a good start, but I don't know the magic.
A solution that is solely inside emacs could be of interest as well.

Answer 1

As you said, Emacs has the --batch option to perform operations with Emacs from the shell. In addition to that, you can use the -l flag to load Emacs Lisp code from a file and execute it, and the -f flag to execute a single Lisp function.
Here is a basic example, which exports a single org-mode file to HTML:
emacs myorgfile.org --batch -f org-html-export-to-html --kill
Perhaps you want something more advanced like exporting/publishing a full org-mode project. I do not have sample code for that, but it should not be too complicated.
I also have a sample Makefile I wrote some time ago to export all org-mode files in the directory to HTML (and also copy the HTML files to another directory):
OUT_DIR=/some/output/dir/html
# Using GNU Make-specific functions here
FILES=$(patsubst %.org,$(OUT_DIR)/%.html,$(wildcard *.org))
.PHONY: all clean install-doc
all: install-doc
install-doc: $(OUT_DIR) $(FILES)
$(OUT_DIR):
mkdir -v -p $(OUT_DIR)
%.html: %.org
emacs $< --batch -f org-html-export-to-html--kill
$(OUT_DIR)/%.html: %.html
install -v -m 644 -t $(OUT_DIR) $<
rm $<
clean:
rm *.html
EDIT:
With Org-mode 8 and the new export engine the function for HTML export has changed.
To make the previous examples work with Org 7 or older, replace org-html-export-to-html with org-export-as-html.

Answer 2

I expect to publish (by the end of this week-end) OrgMk, a suite of Makefile and standalone Bash scripts (usable as well under Cygwin) just to do that! Even more: generation of HTML, Ascii, Beamer, etc.
You'll find it on my GitHub account: https://github.com/fniessen/ (where I already have Emacs configuration files, color themes and other stuff such as an Org Babel refcard -- in progress).

Answer 3

Mark a few org files in dired and call this:
(defun dired-org-to-pdf ()
(interactive)
(mapc
(lambda (f)
(with-current-buffer
(find-file-noselect f)
(org-latex-export-to-pdf)))
(dired-get-marked-files)))
If you know what async is, wrap the call as it can take a while.
update:
Here's a version that combines the awesome dired approach with the lame
other one:)
(defun dired-org-to-pdf ()
(interactive)
(let ((files
(if (eq major-mode 'dired-mode)
(dired-get-marked-files)
(let ((default-directory (read-directory-name "dir: ")))
(mapcar #'expand-file-name
(file-expand-wildcards "*.org"))))))
(mapc
(lambda (f)
(with-current-buffer
(find-file-noselect f)
(org-latex-export-to-pdf)))
files)))