使用PowerShell.exe的启动过程在嵌入的单引号和双引号中表现出不同的行为 [英] Start-Process with PowerShell.exe exhibits different behavior with embedded single quotes and double quotes

问题描述

首先，如果有人想知道为什么我们要以这种方式调用PowerShell，我会使用我们正在构建的更复杂的命令来遇到这种行为，但是可以使用一个更简单的示例来展示该行为，如下所示.实际上，我们在32位PowerShell下以admin身份运行命令，并在字符串中呈现了其他变量(因此，为什么我不简单地在外部使用单引号)，但这似乎并没有行为如下.

First, in case anyone wonders why we're invoking PowerShell in this way, I ran into this behavior with a more complex command we were building, but the behavior can be exhibited using a more simple example as shown below. In practice, we are running a command under 32-bit PowerShell as admin with additional variables rendered in the string (hence why I don't simply use single-quotes for the outer portion), but that doesn't seem to factor into the behavior below.

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当我通过 Start-Process 调用PowerShell时，如果在PowerShell可执行文件的 -Command 参数周围使用单引号，则会出现一些奇怪的行为.例如:

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When I invoke PowerShell through Start-Process, I get some odd behaviors if I use single quotes surrounding the -Command parameter to the PowerShell executable. For example:

Start-Process -FilePath Powershell.exe -ArgumentList "-Command 'ping google.com'"

仅将 ping google.com 呈现为输出并退出.但是，如果我使用嵌套的双引号而不是单引号，如下所示:

just renders ping google.com as the output and exits. However, if I use nested double-quotes instead of the single-quotes as follows:

Start-Process -FilePath Powershell.exe -ArgumentList "-Command `"ping google.com`""

ping 运行并产生预期的输出:

ping runs and produces the expected output:

使用32个字节的数据对google.com [173.194.78.113]执行Ping操作:

Pinging google.com [173.194.78.113] with 32 bytes of data:

从173.194.78.113中回复:字节= 32时间= 34ms TTL = 45

Reply from 173.194.78.113: bytes=32 time=34ms TTL=45

从173.194.78.113中回复:字节= 32时间= 33ms TTL = 45

Reply from 173.194.78.113: bytes=32 time=33ms TTL=45

从173.194.78.113中回复:字节= 32时间= 35ms TTL = 45

Reply from 173.194.78.113: bytes=32 time=35ms TTL=45

从173.194.78.113中回复:字节= 32时间= 32ms TTL = 45

Reply from 173.194.78.113: bytes=32 time=32ms TTL=45

Ping统计为173.194.78.113:

Ping statistics for 173.194.78.113:

数据包:已发送= 4，已接收= 4，丢失= 0(丢失0％)，

Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

大约往返时间(以毫秒为单位):

Approximate round trip times in milli-seconds:

最小值= 32毫秒，最大值= 35毫秒，平均值= 33毫秒

Minimum = 32ms, Maximum = 35ms, Average = 33ms

如果我在 -Command 参数中使用单引号而不是双引号，为什么命令字符串只是按原样呈现而不是执行?

Why does the command string simply render as-is instead of execute if I use the single-quotes for the -Command parameter instead of double-quotes?

推荐答案

js2010的有用答案在使用上是正确的 Start-Process 的代码与您的问题有关，并且行为特定于PowerShell的 CLI ( pwsh ( PowerShell [Core] 6 + ):

js2010's helpful answer is correct in that the use of Start-Process is incidental to your question and that the behavior is specific to PowerShell's CLI (powershell.exe for Windows PowerShell, and pwsh for PowerShell [Core] 6+):

在Windows上 ^[1] ，需要评估 两个层:

On Windows^[1], there are two layers of evaluation to consider:

• (a)将命令行初始解析为参数.

(b)由于使用了 -Command ( -c )CLI参数.

(b) The evaluation of the (space-concatenated) resulting arguments as PowerShell code, due to use of the -Command (-c) CLI parameter.

关于(a):

与Windows上的大多数控制台程序一样，PowerShell仅将"字符(双引号)识别-还将'(单引号)识别为 syntactic函数. ^[2]

As most console programs on Windows do, PowerShell recognizes only " chars. (double quotes) - not also ' (single quotes) - as having syntactic function.^[2]

• 也就是说，除非将"字符转义为 ，否则它们是字符串定界符，而它们本身也会被删除.

• That is, unless " chars. are escaped, they are string delimiters that themselves are removed during parsing.

如上所暗示，'字符.被未删除.

As implied by the above, ' chars. are not removed.

无论参数是什么-可能是"剥离标记的数组-都是级联，它们之间有一个单个空格，(b)的输入.

Whatever arguments are the result - an array of possibly "-stripped tokens - are concatenated with a single space between them, which becomes the input for (b).

要在您的示例上下文中对此进行解释，请从图片中取出 Start-Process :

To explain this in the context of your example, with Start-Process taken out of the picture:

注意:以下适用于从 cmd.exe 或涉及 no shell的任何上下文中调用(包括 Start-Process 和Windows Run( WinKey-R )对话框).相比之下，如果需要， PowerShell 重新引用在幕后的命令行以始终使用" .
换句话说:以下内容适用于命令行 PowerShell 所见.

Note: The following applies to calling from cmd.exe or any context where no shell is involved (including Start-Process and the Windows Run (WinKey-R) dialog). By contrast, PowerShell re-quotes the command line behind the scenes to always use ", if needed.
To put it differently: the following applies to command lines as seen by PowerShell.

单-引用的命令:

Single-quoted command:

# Note: This *would* work for calling ping if run from 
#       (a) PowerShell itself or (b) from a POSIX-like shell such as Bash.
#       However, via cmd.exe or any context where *no* shell is involved,
#       notably Start-Process and the Windows Run dialog, it does not.
powershell -Command 'ping google.com'

• (a)使PowerShell查找以下两个逐字参数:'ping 和 google.com'

  (b)将这些逐字自变量连接起来，形成'ping google.com' ^[2] 并执行作为PowerShell代码，因此输出此字符串文字的内容， ping google.com

  (b) concatenates these verbatim arguments to form 'ping google.com'^[2] and executes that as PowerShell code, therefore outputs the content of this string literal, ping google.com

  双-引用的命令:

  Double-quoted command:

  powershell -Command "ping google.com"
  

  • (a)使PowerShell剥离 syntactic "字符，找到以下单个逐字参数: ping google.com

    • (a) results in PowerShell stripping the syntactic " characters, finding the following, single verbatim argument: ping google.com

      (b)导致该逐字自变量- ping google.com -作为PowerShell代码执行，因此会导致命令调用，即参数为 google.com 的 ping 可执行文件的内容.

      (b) then results in this verbatim argument - ping google.com - being executed as PowerShell code, which therefore results in a command invocation, namely of the ping executable with argument google.com.

      ^{[1]在类Unix平台上，第一层不适用，因为被调用的程序只会看到 verbatim 参数的 array ，而不是他们自己必须解析为参数的命令行.并不是说，如果您从类似POSIX的外壳(例如在类似Unix的平台上的 bash )调用PowerShell CLI，那么正是那个外壳将单引号识别为字符串定界符，并在 PowerShell看到它们之前将它们剥离.}

      ^{[1] On Unix-like platforms, the first layer doesn't apply, because programs being invoked only ever see an array of verbatim arguments, not a command line that they themselves must parse into arguments. Not that if you call the PowerShell CLI from a POSIX-like shell such as bash on Unix-like platforms, it is that shell that recognizes single-quotes as string delimiters, and strips them before PowerShell sees them.}

      ^{[2]令人惊讶的是，在Windows上，最终由每个单独的程序来解释命令行，并且某些 do 选择还识别>'作为字符串定界符(例如Ruby).但是，Windows上的许多程序(包括PowerShell本身)都基于C运行时，该运行时仅识别".}

      ^{[2] Surprisingly, on Windows it is ultimately up to each individual program to interpret the command line, and some do choose to also recognize ' as string delimiters (e.g., Ruby). However, many programs on Windows - including PowerShell itself - are based on the C runtime, which only recognizes ".}

      ^{[3]另外，请注意，这意味着正在进行空白空间标准化:即，
      powershell-命令'ping google.com'同样会导致'ping google.com'.}

      ^{[3] As an aside, note that this implies that whitespace normalization is taking place: that is,
      powershell -Command 'ping google.com' would equally result in 'ping google.com'.}

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