Table of Contents

• :header-args:
• :results
• :session
• :dir
• Fix Invalid function: org-babel-header-args-safe-fn
• Emacs Lisp evaluation of arguments

:header-args: reference

Editor wide

org-babel-default-header-args or org-babel-default-header-args:<lang>

Buffer wide

Note + following R, which append args to the current args. If you omit +, it just overwrites the current args.

#+TITLE: Some title
#+PROPERTY: header-args:R :exports results
#+PROPERTY: header-args:R+ :width 800

Heading wide

* sample header
  :PROPERTIES:
  :header-args:    :cache yes
  :END:

# Language specific
* Heading
  :PROPERTIES:
  :header-args:clojure:    :session *clojure-1*
  :header-args:R:          :session *R*
  :END:

Block wide

#+HEADER: :var data=2
#+BEGIN_SRC emacs-lisp :results both
#+END_SRC

:results reference

:session reference

Specify to make source code blocks share sessions.

:session none (default)

the block gets a new session

:session

the session name is derived from the source language identifier.

:session <name>

blocks with the same name share the session

:dir reference

• :dir specifies the default directory during src code block execution.
• You can use :dir (magit-toplevel) to run the code block on the repository root.

Fix Invalid function: org-babel-header-args-safe-fn howto

Emacs Lisp evaluation of arguments discussion

• Emacs lisp code can set the values for variables.
• To differentiate a value from lisp code, Org interprets any value starting with (, [, ' or ` as Emacs Lisp code.
• The result of evaluating that code is then assigned to the value of that variable.