As with any Unix operating system, Macintosh OS X recognizes the use of environment variables. For a quick refresher, environment variables are traditionally used in shell scripts to retrieve information about the operating environment. Common environment variables are used each time a new Terminal session is launched, including PATH, HOME, and other less common variables. OS X extends this concept with application bundles and Launch Services. Let's begin by examining the traditional use of environment variables by OS X and their associated scope.
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机译：与任何Unix操作系统一样，Macintosh OS X可以识别环境变量的使用。为了快速刷新，传统上在shell脚本中使用环境变量来检索有关操作环境的信息。每次启动新的终端会话时，都会使用公共环境变量，包括PATH，HOME和其他较不常见的变量。 OS X通过应用程序捆绑包和Launch Services扩展了这一概念。让我们开始研究OS X对环境变量的传统用法及其相关范围。
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