Ok, I just found out!  You need to close the device after each plot:

#+begin_src R :results output raw drawer :dir ./
  x <- rnorm(100)
  print(mean(x))
  png(file="hist1.png")
  hist(x)
  dev.off()
  png(file="hist2.png")
  hist(x^2)
  dev.off()
  print("[[./hist1.png]]")
  print("[[./hist2.png]]")
#+end_src

thanks!

On Fri, Jun 7, 2024 at 11:18 AM Ihor Radchenko <yantar92@posteo.net> wrote:

> Giuseppe Pagnoni <gpagnoni@gmail.com> writes:
>
> > Sorry, I just sent you the reply that was meant for Berry's advice :-).
> > Your suggestion also looks very useful, but somehow the png files do not
> > get saved (in the current directory or elsewhere), and I actually do not
> > get any error messages in the R buffer (I also tried to change the file
> > type to jpeg).  Any idea why?
>
> Hard to say.
> Try to run my example in command line R repl.
>
> --
> Ihor Radchenko // yantar92,
> Org mode contributor,
> Learn more about Org mode at <https://orgmode.org/>.
> Support Org development at <https://liberapay.com/org-mode>,
> or support my work at <https://liberapay.com/yantar92>
>


-- 
Giuseppe Pagnoni
Dip. Scienze Biomediche, Metaboliche e Neuroscienze
Sezione Fisiologia e Neuroscienze
Univ. di Modena e Reggio Emilia
Via Campi 287
I-41125 Modena, Italy
Tel: +39-059-205-5742
Fax: +39-059-205-5363