Open URL to resolve DOI with ruby from command line

Based on this I am attempting to use ruby to send a DOI (document object identifier) to crossref.org that should return bibliographic information, making the following call from the command line in WinXP running Ruby 1.9.3-p194:

c:\Ruby193\bin\ruby.exe < rtest.txt

where the file rtest.txt contains

open("http://dx.doi.org/10.1038/nrd842","Accept" => "text/bibliography; style=bibtex"){|f| f.each {|line| print line}}

Instead it doesn't get too far and returns the following:

 -:1:in `initialize': Invalid argument - http://dx.doi.org/10.1038/nrd842 (Errno::EINVAL)
        from -:1:in `open' 
        from -:1:in `<main>'

I can invoke ruby as shown to perform other tasks such as deleting a file (gasp). I am wondering then what might alternately be the cause of the error.

Solution

it seems you must first require a library such as "open-uri" like in the following example:

david@archbox:~$ irb
irb(main):001:0> require 'open-uri'
=> true
irb(main):002:0> open("http://dx.doi.org/10.1038/nrd842","Accept" =>"text/bibliography; style=bibtex"){|f| f.each {|line| print line}}
@article{Atkins_Gershell_2002, title={From the analysts couch: Selective anticancer drugs}, volume={1}, url={http://dx.doi.org/10.1038/nrd842}, DOI={10.1038/nrd842}, number={7}, journal={Nature Reviews Drug Discovery}, publisher={Nature Publishing Group}, author={Atkins, Joshua H. and Gershell, Leland J.}, year={2002}, month={Jul}, pages={491-492}}=> #<StringIO:0x95cf914 @base_uri=#<URI::HTTP:0x95cfcd4 URL:http://data.crossref.org/10.1038%2Fnrd842>, @meta={"date"=>"Mon, 29 Jul 2013 22:54:09 GMT", "server"=>"Apache/2.2.3 (CentOS)", "x-powered-by"=>"Phusion Passenger (mod_rails/mod_rack) 3.0.7", "vary"=>"Accept", "access-control-allow-origin"=>"*", "x-content-type-options"=>"nosniff", "content-length"=>"351", "status"=>"200", "connection"=>"close", "content-type"=>"text/bibliography;charset=utf-8"}, @status=["200", "OK"]>

Create a file to hold your code, perhaps rtest.rb, inside this file paste the following code:

require 'open-uri'
open("http://dx.doi.org/10.1038/nrd842","Accept" =>"text/bibliography; style=bibtex"){|f| f.each {|line| print line}}

Save the file, then run with:

ruby rtest.rb