It is possible to export the code of code blocks, the results of code block evaluation, both the code and the results of code block evaluation, or none. Org defaults to exporting code for most languages. For some languages, such as ditaa, Org defaults to results. To export just the body of code blocks, see Literal Examples. To selectively export sub-trees of an Org document, see Exporting.
The ‘exports’ header argument is to specify if that part of the Org file is exported to, say, HTML or LaTeX formats.
The default. The body of code is included into the exported file. Example: ‘:exports code’.
The results of evaluation of the code is included in the exported file. Example: ‘:exports results’.
Both the code and results of evaluation are included in the exported file. Example: ‘:exports both’.
Neither the code nor the results of evaluation is included in the exported file. Whether the code is evaluated at all depends on other options. Example: ‘:exports none’.
To stop Org from evaluating code blocks to speed exports, use the
header argument ‘:eval never-export’ (see Evaluating Code Blocks).
To stop Org from evaluating code blocks for greater security, set the
org-export-use-babel variable to
nil, but understand that header
arguments will have no effect.
Turning off evaluation comes in handy when batch processing. For example, markup languages for wikis, which have a high risk of untrusted code. Stopping code block evaluation also stops evaluation of all header arguments of the code block. This may not be desirable in some circumstances. So during export, to allow evaluation of just the header arguments but not any code evaluation in the source block, set ‘:eval never-export’ (see Evaluating Code Blocks).
Org never evaluates code blocks in commented sub-trees when exporting (see Comment Lines). On the other hand, Org does evaluate code blocks in sub-trees excluded from export (see Export Settings).