无法从 get-filehash 获取输出 [英] Unable to get output from get-filehash
问题描述
我正在寻找一种可靠的命令行方法来获取 Windows 中文件的 SHA256 哈希值.我的理解是，这样做的方法是在 PowerShell 下通过 Microsoft 的 Get-FileHash cmdlet.我看过几个带有示例的网站，并查看了 Microsoft 自己的文档.以下语法似乎适用于 Windows Server 2012:
I am looking for a reliable command-line method of getting SHA256 hashes for files in Windows. My understanding is that the way to do this is via Microsoft's Get-FileHash cmdlet under PowerShell. I have seen several web sites with examples and reviewed Microsoft's own documentation. It appears that the following syntax should work on Windows Server 2012:
Get-FileHash myfile.txt -Algorithm SHA256
命令运行没有错误，但是没有输出.如果我将输出发送到文件，则创建的文件没有内容.我还看到了将输出通过管道传输到 Format-List 的示例；我试过了，但仍然没有.我也试过用无效参数运行命令，但又没有.
The command runs without error, but there is no output. If I send the output to a file, the file is created with no content. I have also seen examples which pipe the output to Format-List; I tried that, but still nothing. I have also tried running the command with invalid arguments, and again nothing.
我愿意使用不同的程序，但由于业务要求，它需要支持下载.
I am open to using a different program, but due to business requirements, it would need to be a supported download.
推荐答案
我使用的是 PowerShell 4.0，但刚遇到 Get-FileHash 输出为空的相同问题.我的问题的原因与 OP 不同，但我找到了解决我的问题的方法，我想我会为任何来到此页面试图解决 Get 的空输出(或看似不正确的输出)问题的人发布我的发现-FileHash.
I'm using PowerShell 4.0 and I just encountered the same problem of null output from Get-FileHash. The cause of my problem is different than the OP but I have found a solution to my problem and I figured I would post my findings for anyone who came to this page trying to solve the problem of null output (or seemingly incorrect output) from Get-FileHash.
只有当目标文件的路径包含方括号 [ ] 并且这些方括号包含零个字符或 2 个或更多字符时，才会出现问题(对我而言).
The problem only happens (for me) when the path to the target file contains brackets [ ] and those brackets contain either zero characters or 2 or more characters.
我现在明白为什么会这样了.该字符串被解释为正则表达式 (RegEx)，因此方括号 [] 具有其特殊的 RegEx 含义.-LiteralPath 告诉 PowerShell 将字符串解释为简单匹配(无正则表达式).
I now understand WHY this happens. The string is interpreted as Regular Expression (RegEx) so the square brackets [ ] take on their special RegEx meaning. The -LiteralPath tells PowerShell to interpret the string as a simple match (no RegEx).
考虑以下引用 4 个现有文本文件的路径(假设):
Consider the following paths which refer to 4 existing text files (hypothetically):
C:\Test\My Text.txt
C:\Test\My [Text].txt
C:\Test\My [Te]xt.txt
C:\Test\My Text[].txt
以下命令产生正常输出:
The following command produces normal output:
Get-FileHash "C:\Test\My Text.txt"
但是如果使用以下命令会出现空输出:
but there will be null output if using the following commands:
Get-FileHash "C:\Test\My [Text].txt"
Get-FileHash "C:\Test\My [Te]xt.txt"
Get-FileHash "C:\Test\My Text[].txt"
这可以通过使用 -LiteralPath 开关来解决.例如:
This can be solved by using the -LiteralPath switch. For example:
Get-FileHash -LiteralPath "C:\Test\My [Text].txt"
使用 -LiteralPath 开关时，变量会正常展开.例如:
Variables are expanded normally when using the -LiteralPath switch. For example:
(Get-ChildItem C:\Test).FullName | ForEach {
Get-FileHash -LiteralPath $_
}
如果括号之间正好有 1 个字符，则使用 Get-FileHash 时会忽略括号.
If there is exactly 1 character between the brackets, the brackets will be ignored when using Get-FileHash.
考虑以下引用 3 个现有文本文件(假设)的路径，每个文件都有唯一的哈希值:
Consider the following paths which refer to 3 existing text files (hypothetically), each with unique hash values:
C:\Test\My Text.txt
C:\Test\My Tex[t].txt
C:\Test\My[ ]Text.txt
Get-FileHash 以完全相同的方式解释以下所有三个命令(路径被解释为 C:\Test\My Text.txt )因此每个命令都有完全相同的输出，尽管每个文件都有自己独特的哈希值:
Get-FileHash interprets all three of the following commands in exactly the same way ( the path is interpreted as C:\Test\My Text.txt ) and therefore each command has the exact same output despite each file having it's own unique hash value:
Get-FileHash "C:\Test\My Text.txt"
Get-FileHash "C:\Test\My Tex[t].txt"
Get-FileHash "C:\Test\My[ ]Text.txt"
附言我是一个非常新的程序员，请原谅我对术语的错误使用.
P.S. I'm a very new programmer, please forgive me for any poor usage of terminology.
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