If you don’t update Rails, you leave your application and its server open to attack.Here’s advice on timing: If you wait too long to upgrade, the community moves on and you’ll find it difficult get help with any issues.Nokogiri is a gem that is a dependency for many other gems (specifically, the rails-html-sanitizer gem and its dependency, the loofah gem).Nokogiri is a gem that requires compilation for your specific operating system.
I think I have all of this going now, but when I type: Michaels-Mac Book-Pro:~ Paranoid Android$ gem install rails --version=4.0 Building native extensions. ERROR: Error installing rails: ERROR: Failed to build gem native extension. Provided configuration options: --with-opt-dir --without-opt-dir --with-opt-include --without-opt-include=$/include --with-opt-lib --without-opt-lib=$/lib --with-make-prog --without-make-prog --srcdir=.Hundreds of developers use the apps, report problems as they arise, and propose solutions.Rails changes frequently; each application is known to work and serves as your personal “reference implementation.” Support for the project comes from developers who purchase the Capstone Rails Tutorials.Use this simple procedure if you don’t think you’ll need to move back and forth between versions.
Make sure you have committed the Gemfile and files to git so you can restore a known working version of your application if necessary.
/usr/local/rvm/rubies/ruby-1.9.3-p392/bin/ruby *** failed *** Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers. --curdir --ruby=/usr/local/rvm/rubies/ruby-1.9.3-p392/bin/ruby --with-atomic_reference-dir --without-atomic_reference-dir --with-atomic_reference-include --without-atomic_reference-include=$/include --with-atomic_reference-lib --without-atomic_reference-lib=$/lib /usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/mkmf.rb:381:in `try_do': The compiler failed to generate an executable file.