Batch-export org-mode subtree by headline?

Question

Pretext

I am using the emacs batch mode to script the export of .org files to LaTeX via a Makefile, and I am aware of some of the customization options that exist in that regard.

For example, I can (under Emacs 25.2.2 with org-mode 9.1.11) successfully use the command

emacs my.org --batch --eval "(org-latex-export-to-latex nil nil nil t)" --kill

to export only the body (via the fourth argument set to t) of my.org file to my.tex. The arguments of org-latex-export-to-latex are described at https://github.com/emacsmirror/org/blob/master/lisp/ox-latex.el#L3588.

Problem description

I am now looking for a possibility to batch-export a specific subtree from an .org file. In other words, while I have already managed to script the 'body-only' C-e C-b option of a manual org-mode export, I am now trying to also automate its C-e C-s option.

This raises the question of how to identify the desired subtree to-be-exported.

Not quite what I want: Export by ID via .el script

The exact same problem that I am describing is also formulated at

https://lists.gnu.org/archive/html/emacs-orgmode/2015-02/msg00133.html

The responses suggest to export a section by its ID property and include pointers to

• https://code.orgmode.org/bzg/org-mode/src/master/testing/lisp/test-ob.el
• https://code.orgmode.org/bzg/org-mode/src/master/testing/examples/babel.org

for according emacs-lisp code, as well as a more specific emacs-lisp code example, which I can successfully get to export a specific section by its CUSTOM_ID property.

However, this solution has the following flaws:

1. It includes the heading of the section identified by CUSTOM_ID, whereas a subtree exported manually via C-e C-s contains only the content of the exported section (which is what I want).
2. It requires me to specify CUSTOM_IDs, whereas I am hoping to identify the subtree to-be-exported by the text of its headline.
3. It requires emacs-lisp code. :)

Perhaps a better solution: 2nd argument of org-latex-export-to-latex?

The code for org-latex-export-to-latex at https://github.com/emacsmirror/org/blob/master/lisp/ox-latex.el#L3575 shows that its second argument relates to the export of subtrees, and I am wondering whether it can be used to achieve my goals outlined above.

The comment at https://github.com/emacsmirror/org/blob/master/lisp/ox-latex.el#L3588 says:

When optional argument SUBTREEP is non-nil, export the sub-tree at point, extracting information from the headline properties first.

However, the code comment above to me raises the following questions:

• What does "at point" mean?
• How exactly would it "extract information from the headline properties"
• What meaningful non-nil values can I set this option to?

I would appreciate examples of how the second argument of org-latex-export-to-latex can be used in practice.

Answer 1

You can try something like:

emacs my.org --batch --eval \
      "(progn (re-search-forward \"CUSTOM_ID: ${FOO}\") \
              (org-latex-export-to-latex nil t nil t))"

[ Note: 100% untested ]