新手勿怪，webserver 一直在为之前的项目服务，停掉了之前的项目，在新项目重新 执行 rails server 就好了，那个错误也是之前项目的错误，让我搞混了

#4 楼 @hxh1246996371 我怀疑是路由问题，因为它提示这个 rails.root :/Users/XX/.Trash/blog 之前我 new 的 项目名字就是 blog。

#1 楼 @hxh1246996371 Rails 4.2.3

#1 楼 @hxh1246996371 运行了，不起作用，还是提示这个

#3 楼 @michael0015 哈哈，ios 开发一枚，当然得装了

我按照提示，运行了 xcode-select --install ，然后就好了。

下面是整个错误信息：

> ERROR:  Error installing rails:
>   ERROR: Failed to build gem native extension.
>
 >  /Users/qitmac000340/.rvm/rubies/ruby-2.0.0-p643/bin/ruby -r ./siteconf20150818-39064-b7so5m.rb 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
>   --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=/Users/qitmac000340/.rvm/rubies/ruby-2.0.0-p643/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
>
>extconf failed, exit code 1
>
>Gem files will remain installed in /Users/qitmac000340/.rvm/gems/ruby-2.0.0-p643/gems/nokogiri-1.6.6.2 for inspection.
>Results logged to /Users/qitmac000340/.rvm/gems/ruby-2.0.0-p643/extensions/x86_64-darwin-14/2.0.0/nokogiri->1.6.6.2/gem_make.out