posix多值option_argument语法
我已阅读 https://pubs.opengroup.org/onlinepubs/9699919799/basedefs /V1_chap12.html。
据我所知，简短的 option_argument 可能看起来像 -kvalue 或 -k value。
如果我们想为 option_argument 指定多个值，我们可以编写 -kvalue1 -kvalue2、-k value1 -k value2 或混合编写两种语法的。
我的问题：
-k value1 value2 有效且与上述相同吗？
此外，对于长 option_argument 又如何呢？ --key value1 value2 相同吗？
I have read https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html.
I understand that a short option_argument can look like -kvalue or -k value.
If we want to specify multiple values for the option_argument, we can write -kvalue1 -kvalue2, -k value1 -k value2, or a mix of both syntaxes.
My question:
Is -k value1 value2 valid and equivalent to the above?
Further, what about for long option_arguments?
Is --key value1 value2 the same?
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-k value1 value2通常等同于-k value1 -- value2，其中value1是 option_argument code>-k，并且value2是一个操作数（程序参数，如echo value2或ls value2< /代码>）。如果您通过操作optind/OPTIND来实现这一点，您将遇到以下问题：-k value1 value2 ... valueN input-file中，您如何知道input-file是一个输入文件，而不是用作-k input-file？-k -z是否意味着-k有 0 个参数，后跟-z选项，还是-z> 被视为option_argument？那-k value1 value2 -z value4呢？此外，
-k value1 -k value2通常会将value1替换为value2，因此最好记录value1的附加行为code>-k 如果已实现。您应该避免-(和-)选项。在 Solaris 上，根据其 CLIP 准则（向下滚动到命令语法标准：指南部分），（和）字符分隔长选项名称，例如?(help)V(version)会将--help识别为-?并将--version识别为 <代码>-V。至于长选项参数，POSIX 不支持它们，无论是
-old-style arg、--gnu-style=arg还是--gnu -样式arg。根据 POSIX，optstring"-:k:"不可移植，因为-不是字母数字；即使支持，您还需要在--key value1的情况下处理更改optind/OPTIND以将键值设置为value1< /code> 因为key是-选项的 option_argument。如果您只是编写一个实用程序，而不是在自己的选项解析器中实现
getopt规则，则另一种选择是依赖getopt_long，保留 实现差异 牢记；即使 POSIX 没有指定，它也可以广泛使用。您还可以使用单独的选项解析库（或 shell 函数或您正在处理的语言中使用的任何函数）。-k value1 value2is usually equivalent to-k value1 -- value2, wherevalue1is the option_argument to-k, andvalue2is an operand (a program argument like inecho value2orls value2). Were you to implement this by manipulatingoptind/OPTIND, you would have the following problems:-k value1 value2 ... valueN input-file, how would you know thatinput-fileis an input file and not intended as-k input-file?-k -zmean-khad 0 arguments, followed by the-zoption, or is-ztreated as an option_argument? What about-k value1 value2 -z value4?Also,
-k value1 -k value2would typically replacevalue1withvalue2, so it would be a good idea to document the additive behavior of-kif it were implemented. You should avoid-(and-)options. On Solaris, per its CLIP guidelines (scroll down to the Command Syntax Standard: Guidelines section), the(and)characters delimit long option names, like?(help)V(version)would recognize--helpas-?and--versionas-V.As for long option arguments, POSIX does not support them, whether that is
-old-style arg,--gnu-style=arg, or--gnu-style arg. An optstring"-:k:"is not portable according to POSIX either because-is not alphanumeric; even if it is supported, you would also need to deal with changingoptind/OPTINDin the case of--key value1to set the key value tovalue1sincekeyis the option_argument for the-option.If you are merely writing a utility rather than implementing
getoptrules in your own option parser, an alternative would be to rely ongetopt_long, keeping the implementation differences in mind; it is widely available, even if it is not specified by POSIX. You could also use a separate option parsing library (or shell function or whatever you would use in the language you're dealing with).