call shell script from node.js

Question

How can I generate a script in Node.js and pipe to the shell?

E.g. I can create this file, e.g. hello.R, make it executable chmod +x hello.R and run it from the command line, ./hello.R:

#!/usr/bin/Rscript
hello <- function( name ) { return (sprintf( "Hello, %s", name ); })
cat(hello("World"));

What I'd like to do is to do the equivalent from Node. Specifically generate a more complex R script in memory (e.g. as a string using templating, etc.), execute it (using exec or spawn?), and read stdout.

But I can't quite figure out how to pipe a script to R. I tried this (among other things):

var rscript = [       
    hello <- function( name ) { return (sprintf( "Hello, %s", name ); })
    cat(hello("World"));
].join('\n');

var exec = require('child_process').exec;
exec(rscript, { shell: '/usr/bin/R'}, function(err, stdout, stderr) {
   if (err) throw(err);
   console.log(stdout);
});

However, this fails as it seems neither /usr/bin/R nor /usr/bin/Rscript understand the -c switch:

Just for info, you can use the rstats library, alternatively. — Stéphane Laurent
– Stéphane Laurent, Commented Sep 30, 2016 at 17:17

ikrabbe · Accepted Answer · 2015-06-22 17:12:25Z

2

Check the nodejs docs of child_process. You should be able to spawn an Rscript or R command just as you would do on the terminal, and send your commands over child.stdin.

var c = require('child_process');
var r = c.spawn("R","");
r.stdin.write(rscript);
/* now you should be able to read the results from r.stdout a/o r.stderr */

answered Jun 22, 2015 at 17:12

ikrabbe

1,95915 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

prototype Over a year ago

Thanks! It turns out the issue is R and Rscript don't read from stdin by default, and the workarounds (stackoverflow.com/questions/9370609/piping-stdin-to-r) don't play well with spawn. Will noodle on that, for now am writing the code as a file to be read in by R.

Collectives™ on Stack Overflow

call shell script from node.js

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related