英文:
Golang flag parsing after an argument on command line
问题
我正在解析命令行参数。我使用以下代码：
var flagB = flag.Bool("b", false, "boolflag")
func main() {
flag.Parse()
fmt.Println(flag.NArg())
fmt.Println("-b", *flagB)
}
当我像这样执行二进制文件时：
> test -b "random"
我得到了预期的输出，因为有一个参数，并且标志被设置为 true：
1
-b true
然而，当我以另一种方式执行二进制文件时：
> test "random" -b
我得到了这个输出：
2
-b false
现在，标志不再被识别为标志，而是作为另一个参数。
为什么会这样？是否有一个规定，标志应该先出现，然后是参数？我一直以为“GNU方式”传递和解析参数的方式是：在二进制文件之后的位置保留给必需参数。然后，您可以放置可选参数和标志。
英文:
I am parsing command-line arguments. I use the following code:
var flagB = flag.Bool("b", false, "boolflag")
func main() {
flag.Parse()
fmt.Println(flag.NArg())
fmt.Println("-b", *flagB)
}
When I execute the binary like this:
> test -b "random"
I get the expected output, becuase there is one argument, and the flag is set:
1
-b true
However, when I execute the binary the other way around:
> test "random" -b
I get this:
2
-b false
Now, the flag isn't recodnized any more as flag, but as another argument.
Why is it that way? Is there a definition that flags come first and then the arguments? I always thought that the "GNU-way" of passing and parsing arguments is: The first places after the binary are reserved for mandatory arguments. And after that you can put optional arguments and flags.
答案1
得分: 15
flag包不使用GNU解析规则。这些规则在flag包的文档中有解释（http://golang.org/pkg/flag/）。你的问题在那里得到了回答：
在第一个非标志参数之前（“-”是非标志参数）或终止符“--”之后，标志解析停止。
英文:
The flag package does not use GNU parsing rules. The rules are explained in the documentation for flag the package. Your question is answered there:
> Flag parsing stops just before the first non-flag argument ("-" is a non-flag argument) or after the terminator "--".
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