在POSIX shell中是否需要使用command -v选项? posh符合POSIX吗? [英] Is `command -v` option required in a POSIX shell? Is posh compliant with POSIX?

问题描述

我正在使用 posh 来测试要在任何POSIX上成功运行的shell脚本兼容的外壳.这样做时，我发现posh不支持command -v选项. type都不是.

I am using posh to test my shell script that I want to run successfully on any POSIX compliant shell. While doing so, I found that the command -v option is not supported in posh. Neither is type.

我知道不支持type，因为POSIX不需要它.在 https://bugs.debian.org/cgi上对此进行了讨论. -bin/bugreport.cgi?bug = 397601#10 .

I understand that type is not supported because it is not required by POSIX. This is discussed at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=397601#10.

"type"是X/Open扩展名；注意POSIX中的XSI标记 标准.由于POSIX或debian政策并不需要，因此请使用posh 没有实现.

"type" is an X/Open extension; note the XSI marking in the POSIX standard. Since it is not required by POSIX or by debian policy, posh doesn't implement it.

http://pubs.opengroup.org/onlinepubs/009695399/utilities/type.html 确认这一点.请参见提要中的[XSI]边距代码.

http://pubs.opengroup.org/onlinepubs/009695399/utilities/type.html confirms this. See the [XSI] margin code in the synopsis.

但是我不明白为什么posh不支持command -v选项.

But I fail to understand why command -v option is not supported in posh.

有人提到command -v是 https:/可选的/bugs.debian.org/cgi-bin/bugreport.cgi?bug=218530#131 .

根据以下说明，"command -v"是可选功能 http://www.opengroup.org/onlinepubs/009695399/utilities/ 只是提一下.

And "command -v" is an optional functionality according to http://www.opengroup.org/onlinepubs/009695399/utilities/ just to mention it.

但是我无法在 http://pubs.opengroup上确认这一点. org/onlinepubs/009695399/utilities/command.html .

如果不是，posh是否与POSIX不兼容?

If not, is posh is not compliant with POSIX?

推荐答案

这取决于它们兼容的POSIX版本.在POSIX 2004资料中， command 在其中具有-v和-V选项.标准的可选部分-用户可移植性"子集.

It depends on which version of POSIX they're compatible with. In the POSIX 2004 material, command has the -v and -V options in an optional part of the standard — the 'User Portability' subset.

POSIX 2008(2013年修订)未标记 command 具有用户可移植性"子集:

POSIX 2008 (as amended in 2013) does not mark any part of the specification of command with 'User Portability' subset:

简介

command [-p] command_name [argument...]

command [-p][-v|-V] command_name

说明

command实用程序将使Shell将参数视为简单命令，从而抑制了Command Search and Execution，项目1b中描述的Shell函数查找.

DESCRIPTION

The command utility shall cause the shell to treat the arguments as a simple command, suppressing the shell function lookup that is described in Command Search and Execution, item 1b.

如果command_name与其中一个特殊内置实用程序的名称相同，则在特殊内置实用程序开头的枚举列表中的特殊属性将不会出现.在其他各个方面，如果command_name不是函数的名称，则command的效果(无选项)应与省略command相同.

If the command_name is the same as the name of one of the special built-in utilities, the special properties in the enumerated list at the beginning of Special Built-In Utilities shall not occur. In every other respect, if command_name is not the name of a function, the effect of command (with no options) shall be the same as omitting command.

使用-v或-V选项时，command实用程序应提供有关外壳如何解释命令名的信息.

When the -v or -V option is used, the command utility shall provide information concerning how a command name is interpreted by the shell.

2008/2013版本中未列出任何可选标志.在较早的(2004)标准中，-v和-V选项是用户可移植性"子集的一部分，而不是核心的一部分.

There are no optional flags listed in the 2008/2013 version. In the older (2004) standard, the -v and -V options were part of the 'user portability' subset, not part of the core.

因此，如果他们希望遵守已有十多年历史的标准，则不需要-v或-V；如果他们希望符合当前标准(已使用5年以上)，则应支持这些选项.

So, if they want to conform to the standard that is more than a decade old, there's no need for -v or -V; if they want to conform to the current standard (which is more than 5 years old), these options should be supported.

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