注： 我是使用系统自带的 ruby gem，一敲 rails 命令就提示一下信息，所以我就用它提示的命令去安装: Rails is not currently installed on this system. To get the latest version, simply type: $ sudo gem install rails You can then rerun your "rails" command.
有查过一下资料，有的人说是因为系统自带的 ruby 的问题，建议不要用，小弟是小白，对 ruby 不了解，希望各位提点一下；
在 macbook 上使用#sudo gem install rails -V 安装 rails 提示了下面的错误： ....前面一段都没有问题，从下面开始有问题： Building native extensions. This could take a while... /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb checking if the C compiler accepts ... yes checking if the C compiler accepts -Wno-error=unused-command-line-argument-hard-error-in-future... no Building nokogiri using packaged libraries.
The file "/usr/include/iconv.h" is missing in your build environment, which means you haven't installed Xcode Command Line Tools properly.
To install Command Line Tools, try running xcode-select --install on
terminal and follow the instructions. If it fails, open Xcode.app,
select from the menu "Xcode" - "Open Developer Tool" - "More Developer
Tools" to open the developer site, download the installer for your OS
version and run it.
*** 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=/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby --help --clean --use-system-libraries --enable-static --disable-static --with-zlib-dir --without-zlib-dir --with-zlib-include --without-zlib-include=${zlib-dir}/include --with-zlib-lib --without-zlib-lib=${zlib-dir}/lib --enable-cross-build --disable-cross-build ERROR: Error installing rails: ERROR: Failed to build gem native extension.
Building has failed. See above output for more information on the failure.
Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.6.2 for inspection. Results logged to /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.6.6.2/ext/nokogiri/gem_make.out
To install Command Line Tools, try running xcode-select --install on
terminal and follow the instructions
也就是说，需要的编译环境装好了么？
# install command line tools
cd /Applications/Utilities/
xcode-select --install
# select install
gem install rails
