Re: [DISCUSSION] The meaning of :cmdline header argument across babel backends

[Max Nikulin]

On 26/04/2024 20:09, Ihor Radchenko wrote:
> Max Nikulin writes:
>
> > However looking wider, I do not like that :cmdline for ob-shell has
> > different meaning than for other languages, see e.g. ob-sql. Only for
> > shell this parameter is treated as arguments of a *script*. In other
> > cases :cmdline is used to specify arguments of *interpreter* and I think
> > ob-shell should follow this convention.
>
> Alas, we already have the current state of affairs documented in
> https://orgmode.org/worg/org-contrib/babel/languages/ob-doc-shell.html#orge70bc7b
>
> So, no breaking changes.

It is documented as
" :cmdline <arg_1> ... [arg_n]

Use the :cmdline header arg to pass arguments to a shell command."

However current implementation allows code injection through args, 
including a trivial one

#+header-arg: :results verbatim
#+begin_src sh :cmdline 1 ; touch /tmp/not-an-arg
  printf '%s\n' "$@"
#+end_src

#+RESULTS:
: 1

"touch ..." *are not arguments of the script*. So users should be 
careful to get documented behavior.

> And shell scripts are not like SQL queries - they often do need to check
> arguments. So, the current behaviour is justified, IMHO.

stackoverflow is full of suggestion how to pass arguments to a SQL 
script executed by mysql. Unfortunately it is unsafe and allows 
injection of code. psql (PostgreSQL) allows to pass parameters, however 
it is more like :var than script arguments. So it is true that CLI 
clients for SQL databases do not implement positional parameters.

ARGV is treated in a quite specific way by awk. It may contain file 
names, variable assignments, and might be overwritten in BEGIN block. 
However a close ob-awk header argument is :cmd-line, not :cmdline, so 
inconsistency is even greater.

> What might be done is introducing _two_ different header arguments - one
> for interpreter switches, and another for script/program switches.
>
> Say, :interpreter-cmdline and :script-cmdline.
> Then, we can call the current :cmdline behaviour "dwim" and allow users
> to be more explicit if necessary.

It is too easy to confuse org-babel, so "dwim" works in simple cases 
only. Independent header arguments make things more clear, I would 
prefer :script-args. The question is whether they should be interpreted 
by shell (flexibility and shooting feet) or more strict syntax `("hello 
world" 1 a) should be used.