尝试安装特定 gem 'oily_png (1.2.0)' MAC OS X El Capitan 时出错

Getting an error trying to install a particular gem 'oily_png (1.2.0)' MAC OS X El Capitan

我在 mac OS X El Capitan 上,在尝试 运行 捆绑安装后,我收到以下错误:

谁能帮我解决这个问题?

在 Mac 上,任何时候升级 Xcode 或操作系统,似乎都有可能删除命令行工具。

 xcode-select --install 

在终端 window 中,将安装工具,这也可以在 xcode 应用程序中完成。

[~] xcode-select -h
Usage: xcode-select [options]

Print or change the path to the active developer directory. This directory
controls which tools are used for the Xcode command line tools (for example,
xcodebuild) as well as the BSD development commands (such as cc and make).

Options:
  -h, --help                  print this help message and exit
  -p, --print-path            print the path of the active developer directory
  -s <path>, --switch <path>  set the path for the active developer directory
  --install                   open a dialog for installation of the command line developer tools
  -v, --version               print the xcode-select version
  -r, --reset                 reset to the default command line tools path

如果您安装了不止一套工具(例如测试版),-s, --switch 标志也有助于将其指向您要使用的工具(或者如果它指向的版本已删除)