Tangle only selected src blocks using org-babel on export

Question

I have a document with only several source code blocks that should be tangled. So the structure is:

    # Some main.org
    ...
    #+BEGIN_SRC awk :tangle file1.awk
    ...
    #+END_SRC awk
    ...
    ...
    #+BEGIN_SRC awk :tangle file2.awk
    #+END_SRC
    ...

Firstly, I have noticed that just exporting main.org is not goint to trigger tangling. Then, I decided to add a call to (org-babel-tangle) somewhere at the top of main.org. This call will produce file1.awk and file2.awk, but will also have an undesired side-effect of tangling the entire main.org file (#+INCLUDE directives substituted with contents of the included files, macros substituted, ...) into, well, main.org. How to avoid this behavior and produce only the files intended for tangling?

Answer 1

The following org-file works for me with emacs 25.3.2 and org-version 9.1.6:

# Some main.org
#+BEGIN_SRC emacs-lisp :results silent :exports results
(org-babel-tangle)
#+END_SRC
#+INCLUDE includeFile.org
#+BEGIN_SRC emacs-lisp :tangle file1.el
"Contents of file1.el"
#+END_SRC

#+BEGIN_SRC emacs-lisp :tangle file2.el
"Contents of file2.el"
#+END_SRC

The contents of includeFile.org for that test is:

* This is includeFile.org
Some text here.

After export to HTML the files file1.el and file2.el are tangled and I am notified that main.org has changed but the contents of main.org remains the same after answering with y and also after M-x revert-buffer. The relevant content of the generated html file is: