Set-Content 在我的文件末尾附加一个换行符(换行符，CRLF) [英] Set-Content appends a newline (line break, CRLF) at the end of my file

问题描述

我的原始配置文件 (web1.config) 没有多余的行，在记事本中查看时(显示所有字符)如下所示:

My original config file (web1.config) has no extra line and when viewed in notepad (showing all characters) looks as:

 <?xml version="1.0"?>
<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.6" />
    <httpRuntime targetFramework="4.6" />
  </system.web>
  <appSettings>
    <add key="myConnectionString" value="server=localhost;database=myDb;uid=myUser;password=myPass;" />
  </appSettings>
</configuration>

现在，我需要应用脚本将我的数据库名称更改为其他类似的名称:

Now, I need to apply the script to change my database name to something else which looks like:

 Move-Item "web1.config" "webtemp.config"
Get-Content "webtemp.config" | ForEach-Object {$_ -replace "database=myDb;", "database=newDb;"} |Set-Content "web1.config" -Force
Remove-Item "webtemp.config"
Write-Output('Settings Changed')

因此，生成的新文件 (web1.config) 如下所示:

So, the new file (web1.config) generated looks as:

注意文件末尾添加的额外行(完全不需要)我尝试了所有其他选项，例如:- 使用输出文件 api- 使用 .net IO 方法 System.IO.StreamWriter- 使用 -nonewline 标志(它将所有 10 行转换为单行)- 使用不同的编码选项- 尝试将 替换为 (不要再次工作，因为 set-content 总是会生成 crlf)

Notice the extra line added at the end of the file (which is completely not needed) I tried all other options such as: - using out-file api - using .net IO method System.IO.StreamWriter - using -nonewline flag (it converts all 10 lines into single line) - using different encoding options - tried replacing to (don't work as again set-content generates the crlf always)

我使用的是 PowerShell v5.1.

I'm using PowerShell v5.1.

推荐答案

tl;dr(PSv5+；旧版本见底部):

(Get-Content webtemp.config) -replace 'database=myDb;', 'database=newDb;' -join "`n" |
  Set-Content -NoNewline -Force web1.config

^{注意:替换`n"; 与 "`r`n"; 如果你想要 Windows 风格的 CRLF 行结尾而不是 Unix 风格的 LF-only 行结尾(PowerShell 和许多实用程序都可以处理).}

^{Note: Replace "`n" with "`r`n" if you want Windows-style CRLF line endings rather than Unix-style LF-only line endings (PowerShell and many utilities can handle both).}

在PSv5+中，Set-Content支持-NoNewline开关，它指示Set-Content 不要在每个输入对象后添加换行符(换行符).这同样适用于 Add-Content 和 Out-File cmdlet.

In PSv5+, Set-Content supports the -NoNewline switch, which instructs Set-Content not to add a newline (line break) after each input object. The same applies analogously to the Add-Content and Out-File cmdlets.

换句话说:Set-Content -NoNewline 直接连接所有输入对象的字符串表示:

In other words: Set-Content -NoNewline directly concatenates the string representations of all its input objects:

PS> 'one', 'two' | Set-Content -NoNewline tmp.txt; Get-Content tmp.txt
onetwo

如果你传递给 Set-Content -NoNewline 的是一个 单个字符串，它已经嵌入了换行符，你可以使用它按原样获得所需的结果:

If what you're passing to Set-Content -NoNewline is a single string that already has embedded newlines, you can use it as-is and get the desired result:

PS> "one`ntwo" | Set-Content -NoNewline tmp.txt; "$(Get-Content -Raw tmp.txt)?"
one
two?

请注意，Get-Content -Raw 将文件作为一个整体读取，原样(除了字符解码)以及 ? 直接出现在 two 之后表示文件没有尾随换行符.

Note that Get-Content -Raw reads the file as a whole, as-is (aside from character decoding) and the fact that the ? appears directly after two implies that the file has no trailing newline.

就您而言，由于您正在一个接一个处理输入行(通过 Get-Content without -Raw) 并因此输出一个 array 行(字符串)，您必须首先用换行符将它们连接起来作为 分隔符 - 仅在行之间 - 并将结果传递给 Set-Content -NoNewline，如顶部所示；这是一个简化的例子:

In your case, since you're processing input lines one by one (via Get-Content without -Raw) and therefore outputting an array of lines (strings), you must first join them with a newline as the separator - between lines only - and pass the result to Set-Content -NoNewline, as shown at the top; here's a simplified example:

PS> ('one', 'two') -join "`n" | Set-Content -NoNewline tmp.txt; "$(Get-Content -Raw tmp.txt)?"
one
two?

'one', 'two' 是一个双元素字符串数组，它是您的逐行处理命令的替代品.

'one', 'two' is a two-element string array that is a stand-in for your line-by-line processing command.

编码说明:

在 Windows PowerShell 中，Set-Content 默认情况下会根据系统的旧单字节代码页生成ANSI"编码的文件.
要明确控制编码，请使用 -Encoding 参数.

In Windows PowerShell, Set-Content produces "ANSI"-encoded files by default, based on your system's legacy, single-byte code page.
To control the encoding explicitly, use the -Encoding parameter.

在 PSv4- 中，需要使用 .NET Framework 的解决方案:

In PSv4-, a solution that uses the .NET Framework is needed:

PS> [System.IO.File]::WriteAllText('tmp.txt', ('one', 'two') -join "`n"); "$(Get-Content -Raw tmp.txt)?"
one
two?

请注意，[System.IO.File]::WriteAllText()，在没有编码参数的情况下，默认为BOM-less UTF-8.
传递所需的 [System.Text.Encoding] 编码实例作为需要的第三个参数.

Note that [System.IO.File]::WriteAllText(), in the absence of an encoding argument, defaults to BOM-less UTF-8.
Pass the desired [System.Text.Encoding] encoding instance as the 3rd argument as needed.

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