Do you mean interactively?  With org-babel-tangle you can:

With one universal prefix argument, only tangle the block at point.

When two universal prefix arguments, only tangle blocks for the
tangle file of the block at point.


John

-----------------------------------
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu



On Thu, Oct 11, 2018 at 3:18 AM Alan Schmitt <alan.schmitt@polytechnique.org>
wrote:

> Hello,
>
> I'm moving my configuration files to an org file to be tangled, and I
> have a couple questions.
>
> First, is there a command to tangle a single block, or blocks in a
> subtree?
>
> Second, I like to have the :comments link option in my tangled files (to
> reference where they were tangled from), but some files do not have an
> emacs mode, so I use a "config" source block. For these files, org does
> not know the syntax of comments, so it asks me for it. Can I specify the
> syntax for comments in the header of the source block?
>
> Thanks a lot,
>
> Alan
>
> --
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> Monthly Athmospheric CO₂, Mauna Loa Obs. 2018-09: 405.51, 2017-09: 403.37
>