Mac OS下使用rvm install命令安装Ruby报错问题解决（Xcode version older than...）
1，问题描述
（1）前段时间 Mac 系统升级成最新版本 。想要使用 rvm 安装一个指定版本的 Ruby：
rvm install 2.4.1
（2）命令执行后安装失败，报如下错误：
MacBook:hangge_2227 hangge$ rvm install 2.4.1
Warning, new version of rvm available '1.29.4', you are using older version '1.29.3'.
You can disable this warning with: echo rvm_autoupdate_flag=0 >> ~/.rvmrc
You can enable auto-update with: echo rvm_autoupdate_flag=2 >> ~/.rvmrc
Searching for binary rubies, this might take some time.
No binary rubies available for: osx/10.13/x86_64/ruby-2.4.1.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for osx.
Installing requirements for osx.
Updating system...........-
Xcode version older than 4.6.2 installed, download and install newer version from:
http://connect.apple.com
After installation open Xcode, go to Downloads and install Command Line Tools.
.
Error running 'requirements_osx_brew_update_system ruby-2.4.1',
please read /Users/hangge/.rvm/log/1543467646_ruby-2.4.1/update_system.log
Requirements installation failed with status: 1.
2，解决办法
（1）首先执行如下命令升级 rvm
rvm get master
（2）再次安装即可。
rvm install 2.4.1
