[Rd] R as shell script

[Juha Vierinen]

Hi Jeffrey!

Great work with rinterp! I had barely read into the R embedded API and
somebody implements exactly what I need. Thank you! I played around
with it a bit and I was able to access stdin() without any
modifications, I have added a stdin example to the wiki. I hope this
can be considered for inclusion to the R distribution.

I took a quick stab at adding making a copy of argc and argv to the R
script, but those macros look quite scary, so I might be doing many
more mistakes than I am aware of (hint: malloc). Now command line
arguments are also passed, and the following also works:

--------args.r:
#!/usr/bin/rinterp

cat("n args: ")
cat(argc)
cat("\n")
for (i in 1:argc)
{
  cat(sprintf("arg %d = %s\n",i,argv[i]))
}
-------------

> ./args.r a b c
n args: 4
arg 1 = ./args.r
arg 2 = a
arg 3 = b
arg 4 = c

The attachment contains the new rinterp.c

juha

On 7/14/06, Jeffrey Horner <jeff.horner at vanderbilt.edu> wrote:
> Juha Vierinen wrote:
> > Hi,
> >
> > I am considering if I should invest in learning R. Based on the
> > language definition and introductory documents, it seems nice. But now
> > I am faced with a problem: I want to be able to run R programs easily
> > from the unix shell, and write scripts that can automatically select R
> > as the interpreter:
> >
> > #!/usr/bin/R
> > cat("Hello world.\n")
> >
> > This of course doesn't work, because /usr/bin/R is a shell script.
> >
> > I have been able to create a binary wrapper that calls R with the
> > correct arguments, which is documented here:
> >
> > http://kavaro.fi/mediawiki/index.php/Using_R_from_the_shell
> >
> > This still lacks eg. standard input (but I have no idea how I can
> > implement it in R) and full command line argument passing (can be
> > done), but am I on the right track, or is there already something that
> > does what I need?
>
> If you search the mailing list archives:
>
> http://tolstoy.newcastle.edu.au/R/
>
> you can find entries like the following (searching on "bang"):
>
> http://tolstoy.newcastle.edu.au/R/devel/05/01/1910.html
>
> which implements similar functionality. But I thought this would be a
> fun little (distracting) project, so I created an R wiki page:
>
> http://wiki.r-project.org/rwiki/doku.php?id=developers:rinterp
>
> with source code describing how to solve this problem by embedding R
> within your C program. Here's the main function:
>
> /* rinterp: shebang support for R
>   *
>   * Usage:
>   *
>   * From the command line:
>   * $ rinterp filename
>   *
>   * In a file:
>   * --------------------
>   * #!/path/to/rinterp
>   * cat("hello world\n");
>   * --------------------
>   */
> int main(int argc, char **argv){
>
>      /* R embedded arguments */
>      char *R_argv[] = {"RINTERP", "--gui=none", "--slave", "--silent",
> "--vanilla","--no-readline"};
>      int R_argc = sizeof(R_argv)/sizeof(R_argv[0]);
>
>      struct stat sbuf;
>
>      /* Setenv R_HOME: insert or replace into environment.
>       * The RHOME macro is defined during configure
>       */
>      if (setenv("R_HOME",RHOME,1) != 0){
>          perror("ERROR: couldn't set/replace R_HOME");
>          exit(1);
>      }
>
>      /* Assume last argument is the file we want to source.
>       * Ignore other args for now.
>       */
>      if (argc > 1) {/* don't try and source rinterp binary */
>          if (stat(argv[argc-1],&sbuf) != 0){
>              perror(argv[argc-1]);
>              exit(1);
>          }
>      } else {
>          fprintf(stderr,"Usage: rinterp filename\n");
>          exit(1);
>      }
>
>      /* Initialize R interpreter */
>      Rf_initEmbeddedR(R_argc, R_argv);
>
>      /* Now call R function source(filename) */
>      call_fun1str("source",argv[argc-1]);
>
>      exit(0);
> }
>
> Feel free to logon to the R wiki and contribute to the page. I think it
> would be interesting to solve this once and for all.
>
> Cheers!
> --
> Jeffrey Horner       Computer Systems Analyst         School of Medicine
> 615-322-8606         Department of Biostatistics   Vanderbilt University
>
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