mac环境下ruby更新

环境 

    mac版本10.12.6 Sierra

    原本想升级cocoapods，但是发现需要先升级gem,升级gem后，发现总是出现如下问题：    

YAML safe loading is not available. Please upgrade psych to a version that supports safe loading (>= 2.0).

ERROR:  SSL verification error at depth 1: unable to get local issuer certificate (20)

ERROR:  You must add /O=Digital Signature Trust Co./CN=DST Root CA X3 to your local trusted store

    查了一下原因说是需要升级ruby.

升级ruby网上资源很多，参考链接如下：RVM 实用指南 · Ruby China

    过程中又遇到如下问题：

    Error running 'requirements_osx_brew_libs_install libtool coreutils libyaml readline libksba openssl@1.1',

please read /Users/qixin/.rvm/log/1520495237_ruby-2.4.0/package_install_libtool_coreutils_libyaml_readline_libksba_openssl@1.1.log

Requirements installation failed with status: 1.

    stack overflow 中找到的大概解决方法链接：ruby - Error running 'requirements_osx_brew_libs_install...' on Mac 10.7 - Stack Overflow

    重要步骤在于，在终端执行如下命令：$ brew install sqlite

    然后遇到提示：

    Xcode alone is not sufficient on Sierra.

Install the Command Line Tools:

  xcode-select --install

此时，按提示在终端执行，$xcode-select --install， 即可，

安装完成后，执行， brew install sqlite，然后成功后，便可执行 rvm install 2.4.0 --disable-binary 安装新的ruby 了。