The installation is easy enough once you have R correctly installed.
Here are the steps on Ruby 1.8.7, with Gems >1.8 (probably the same on all version).
If you just try the basic Gem installation you get:
sudo gem install rsruby
Fetching: rsruby-0.5.1.1.gem (100%)
Building native extensions. This could take a while...
ERROR: Error installing rsruby:
ERROR: Failed to build gem native extension.
/usr/bin/ruby1.8 extconf.rb
checking for main() in -lR... no
ERROR: Cannot find the R library, aborting.
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers. Check the mkmf.log file for more
details. You may need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/usr/bin/ruby1.8
--with-R-dir
--without-R-dir
--with-R-include
--without-R-include=${R-dir}/include
--with-R-lib
--without-R-lib=${R-dir}/lib
--with-Rlib
--without-Rlib
So you need to add some appropriate switches to enable the builder to find the R libraries.
Assuming you have R already installed, they are likely (under Ubuntu) to be at:
/usr/lib/R = binaries
/usr/share/R/include = build libraries
First create an environment variable for the R binaries:
~$ export R_HOME=/usr/lib/R
then add this to your load path:
~$ export LD_LIBRARY_PATH=\$LD_LIBRARY_PATH:R_HOME/bin
Now, retry the installation:
~$ sudo gem install rsruby -- --with-R-dir=/usr/lib/R --with-R-include=/usr/share/R/include
Building native extensions. This could take a while...
Successfully installed rsruby-0.5.1.1
1 gem installed
Installing ri documentation for rsruby-0.5.1.1...
Installing RDoc documentation for rsruby-0.5.1.1...
Test out the rsruby gem:
~$ irb
irb(main):001:0> require 'rubygems'
=> true
irb(main):002:0> require 'rsruby'
=> true
irb(main):003:0> r = RSRuby.instance
=> #-2147483648, "parse"=>#, "help"=>#, "NaN"=>NaN, "FALSE"=>false, "TRUE"=>true, "eval"=>#, "F"=>false, "T"=>true, "helpfun"=>#, "get"=>#}, @proc_table={}, @class_table={}, @default_mode=-1>
irb(main):004:0> r.help
=> "/usr/lib/R/library/base/help/NULL"
irb(main):005:0> exit
Just remember to set R_HOME permanently for your user in wherever you choose to add environment variables.
