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我找了一个代码块我使用(从采购的另一个问题),我一直没能找出什么.在.{process表示这个片段(评论删除):

Get-ItemProperty $path |
.{process{ if ($_.DisplayName -and $_.UninstallString) { $_ } }} |
Select-Object DisplayName, Publisher, InstallDate, DisplayVersion, HelpLink, UninstallString |
Sort-Object DisplayName

我知道,%是For-EachObject和?是简写形式,Where或Where-Object,但接下来的问题是:

什么是.速记？

大多数时候，powershell 中的错误报告非常有用。我看到错误，看到起源，但我注意到 ForEach-Object 管道中的任何错误都会丢失其起源行，并且错误堆栈仅指向带有ForEach-Object.

错误位置示例

Set-StrictMode -Version Latest
$ErrorActionPreference = "Stop"

[cultureinfo]::CurrentUICulture = 'en-US'

function Test-Something($val)
{
    # var is not defined here
    Write-Host($undefined_variable)
}

@("a","b") | ForEach-Object{
    $entry = $_

    Test-Something $entry
}

结果是

ForEach-Object : The variable '$undefined_variable' cannot be retrieved because it has not been set.
In D:\dummy.ps1:12 Line:14
+ @("a","b") | ForEach-Object{
+              ~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (undefined_variable:String) [ForEach-Object], RuntimeException
    + FullyQualifiedErrorId : VariableIsUndefined,Microsoft.PowerShell.Commands.ForEachObjectCommand

该线12指向@("a","b") | ForEach-Object{，这显然不是错误位置。

foreach 的更有用的示例 …