如何使用gem在Ubuntu上安装Rails
错误消息：
Building native extensions. This could take a while... ERROR: Error installing rails: ERROR: Failed to build gem native extension. /usr/bin/ruby2.1 -r ./siteconf20150328-1540-hff2f0.rb extconf.rb checking if the C compiler accepts ... *** 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/ruby2.1 --help --clean /usr/lib/ruby/2.1.0/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError) You have to install development tools first. from /usr/lib/ruby/2.1.0/mkmf.rb:571:in `block in try_compile' from /usr/lib/ruby/2.1.0/mkmf.rb:522:in `with_werror' from /usr/lib/ruby/2.1.0/mkmf.rb:571:in `try_compile' from extconf.rb:80:in `nokogiri_try_compile' from extconf.rb:87:in `block in add_cflags' from /usr/lib/ruby/2.1.0/mkmf.rb:621:in `with_cflags' from extconf.rb:86:in `add_cflags' from extconf.rb:337:in `<main>' extconf failed, exit code 1 Gem files will remain installed in /var/lib/gems/2.1.0/gems/nokogiri-1.6.6.2 for inspection. Results logged to /var/lib/gems/2.1.0/extensions/x86_64-linux/2.1.0/nokogiri-1.6.6.2/gem_make.out configuration：
- Ubuntu 14.10（GNU / Linux 3.16.0-23-generic x86_64）
- gcc（Ubuntu 4.9.1-16ubuntu6）4.9.1
- ruby 2.1.2p95（2014-05-08）[x86_64-linux-gnu]
在使用RVM在Ubuntu 14.04上升级到Rails 4.2.4后，我需要这样做：
sudo apt-get install libgmp-dev
要么
sudo apt-get install libgmp3-dev
Full stacktrace： http: //ruby-on-rails-eq8.blogspot.co.uk/2015/10/solving-ubuntu-1404-ruby-c-dependancy.html
你似乎缺less一些Ruby要求。 如果您正在使用RVM，请尝试：
rvm requirements
获取依赖关系列表并手动安装。
否则，请直接使用以下安装已知的基本要求：
sudo apt-get install build-essential bison openssl libreadline6 libreadline6-dev curl git-core zlib1g zlib1g-dev libssl-dev libyaml-dev libxml2-dev autoconf libc6-dev ncurses-dev automake libtool
你得到这个错误，因为Ruby的开发依赖关系丢失。
我build议你安装和使用RVM来解决这个问题，查看官方和更新说明https://rvm.io/rvm/install
当我回答这个问题时，我遵循了以下步骤：
gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 \curl -sSL https://get.rvm.io | bash
如果你得到这个警告
* WARNING: You have '~/.profile' file, you might want to load it, to do that add the following line to '/home/mao/.bash_profile': source ~/.profile
执行这个命令：
echo source ~/.profile >> ~/.bash_profile
然后，通过执行以下命令重新加载/应用刚更新的bash_profile：
source ~/.bash_profile
最后运行这个来安装要求：
rvm requirements
这应该适用于Ubuntu，Fedora，Debian，Redhat，Slackware等Linux发行版。
对于Centos 7，Redhat 7：
yum -y install gcc ruby-dev
