如何捕获Get-Childitem访问目录被拒绝时的错误？

尝试用try/catch块捕获Get-ChildItem的UnauthorizedAccessException错误，但始终失败，代码片段如下：

if((Test-Path .\test.txt)){
    $key = Get-Content -Path .\test.txt
} else {
  write-host "test.txt file not found in current folder. Searching for it in other folders." -ForegroundColor DarkCyan
  try {
        $key = @(gci -path $env:USERPROFILE -file test.txt -Recurse -ErrorVariable ers )[0]  
      } catch [System.UnauthorizedAccessException]{ 
        write-warning -Message "Folder offlimits" 
      } catch [RuntimeException]{
        write-warning -Message "Some other error occured"  
      } finally {
        write-host $key.FullName
      }
            
}

执行后，$ers中出现的错误内容：

gci : Access to the path 'C:\User\Search\Data' is denied.
At line:6 char:26
+ ...    $key = @(gci -path $env:USERPROFILE -file test.txt -Recurse  -Error ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : PermissionDenied: (C:\User\Search\Data:String) [Get-ChildItem], UnauthorizedAccessException
    + FullyQualifiedErrorId : DirUnauthorizedAccessError,Microsoft.PowerShell.Commands.GetChildItemCommand

解决思路 #

• 核心原因：PowerShell的try/catch仅捕获终止性错误，而Get-ChildItem遇到权限拒绝时抛出的是非终止性错误，这类错误默认不会中断执行，也不会触发catch块。

• 修正方法：在gci命令中添加-ErrorAction Stop参数，强制将非终止性错误转为终止性错误，这样就能被try/catch捕获：

if((Test-Path .\test.txt)){
    $key = Get-Content -Path .\test.txt
} else {
  write-host "test.txt file not found in current folder. Searching for it in other folders." -ForegroundColor DarkCyan
  try {
        # 添加-ErrorAction Stop参数，将非终止错误转为终止错误
        $key = @(gci -path $env:USERPROFILE -file test.txt -Recurse -ErrorVariable ers -ErrorAction Stop )[0]  
      } catch [System.UnauthorizedAccessException]{ 
        write-warning -Message "Folder offlimits" 
      } catch [System.Exception]{
        # 兜底捕获其他终止性错误，$_可查看错误详情
        write-warning -Message "Some other error occurred: $_"  
      } finally {
        # 增加空值判断，避免$key为空时报错
        if ($key) { write-host $key.FullName }
      }
            
}

• 额外说明：
  • 若不想针对单个命令设置，也可以在try块前临时修改全局错误偏好：$originalErrorAction = $ErrorActionPreference; $ErrorActionPreference = 'Stop'，执行完成后再恢复原设置。
  • 捕获System.Exception可以兜底处理所有未明确指定的终止性错误，方便排查其他未知问题。

内容的提问来源于stack exchange，提问作者Matt Williamson