dpa55065
2019-07-06 15:27
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用类似bash的环境变量引用插入字符串

I have an input string for my Golang CLI tool with some references to environment variables in bash syntax ($VAR and ${VAR}), e.g.:

$HOME/somedir/${SOME_VARIABLE}dir/anotherdir-${ANOTHER_VARIABLE}

What is the most efficient way to interpolate this string by replacing environemnt variables references with actual values? For previous example it can be:

/home/user/somedir/4dir/anotherdir-5

if HOME=/home/user, SOME_VARIABLE=4 and ANOTHER_VARIABLE=5.

Right now I'm using something like:

func interpolate(str string) string {
        for _, e := range os.Environ() {
                parts := strings.SplitN(e, "=", 2)
                name, value := parts[0], parts[1]
                str = strings.Replace(str, "$" + name, value, -1)
        }
        return str
}

but this code doesn't handle ${} variables.

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我为Golang CLI工具输入了一个输入字符串,并以bash语法( $ VAR $ {VAR} ),例如:

  $ HOME / somedir /  $ {SOME_VARIABLE} dir / anotherdir-$ {ANOTHER_VARIABLE} 
   
 
 

通过用实际值替换环境变量引用来插值此字符串的最有效方法是什么? For 上一个示例可以是:

  / home / user / somedir / 4dir / anotherdir-5 
   HOME = / home / user  SOME_VARIABLE = 4  ANOTHER_VARIABLE = 5 ,则pre> 
 
 

现在我正在使用类似的东西:

  func interpolate(str string)string {
 对于_,e:= range os.Environ(){
 parts:= strings.SplitN(e,“ =”,2)
 name,value:= parts [0],par  ts [1] 
 str = strings.Replace(str,“ $” +名称,值,-1)
} 
返回str 
} 
   
 
 <  p>,但是此代码无法处理 $ {} 变量。 
 
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1条回答 默认 最新

  • droi5225 2019-07-06 16:37
    已采纳

    Use os.ExpandEnv:

    s := os.ExpandEnv(
        "$HOME/somedir/${SOME_VARIABLE}dir/anotherdir-${ANOTHER_VARIABLE}")
    

    You can use os.Expand for the case where the values are not taken from environment variables:

    m := map[string]string{
        "HOME":             "/home/user",
        "SOME_VARIABLE":    "4",
        "ANOTHER_VARIABLE": "5",
    }
    s := os.Expand(
        "$HOME/somedir/${SOME_VARIABLE}dir/anotherdir-${ANOTHER_VARIABLE}", 
        func(s string) string { return m[s] })
    

    Run it in the playground.

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