GNU make manual 翻译( 一百六十一)

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6.4 How Variables Get Their Values
==================================

Variables can get values in several different ways:

   * You can specify an overriding value when you run `make'.  *Note
     Overriding Variables: Overriding.

   * You can specify a value in the makefile, either with an assignment
     (*note Setting Variables: Setting.) or with a verbatim definition
     (*note Defining Multi-Line Variables: Multi-Line.).

   * Variables in the environment become `make' variables.  *Note
     Variables from the Environment: Environment.

   * Several "automatic" variables are given new values for each rule.
     Each of these has a single conventional use.  *Note Automatic
     Variables::.

   * Several variables have constant initial values.  *Note Variables
     Used by Implicit Rules: Implicit Variables.

6.4 变量如何使用它们的值
==================================

变量可以通过以下几个方式来获得它们的值:

*在你运行make的时候你可以设定一个覆盖值。*Note Overriding Variables :Overriding.

*你可以在makefile中指定一个值，或者用赋值语句(*note Setting Variables: Setting.)，或者用逐字逐句地定义(*note Defining Multi-Line Variables: Multi-Line.)

*在环境中的变量便成为 make 的变量。*Note Variables from the Environment:　Environment.　　

*有几个自动的变量在每一个规则李被赋予新的值。每一个值都有一个单独的应用。*Note Automatic Variables::

*有几个变量有固定的初始值。*Note Variables Used by Implicit Rules: Implicit Variables.

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