无法收集停止Powershell脚本的错误信息

Question

我正在编写一个脚本，该脚本将监视任何新的mp4文件的目录，然后使用HandBrake的CLI工具转换该文件。监视目录更改的逻辑本身是有效的，但是如果我将大视频放入“已监视”目录，转换就会失败，因为只要文件有时间完成复制，它就会在启动时看到新文件。

我正在使用do until循环来检查文件是否锁定/下载，然后一旦文件解锁/写入就继续。循环可以作为一个独立的脚本，但在文件系统中使用时，守望者的脚本将没有任何错误，停止在这条线：

[System.IO.FileStream] $fs = $convertingFile.OpenWrite();

不管出现这种情况，如果$ ErrorActionPreference =“SilentlyContinue”的评论出。我一直无法收集任何日志输出，以了解脚本使用启动脚本或外部文件停止的原因。

我应该如何最好地收集有关为什么脚本一旦遇到此线路就停止的错误信息？

奖励：为什么这个脚本不能提供错误信息？

$ErrorActionPreference = "SilentlyContinue" 

    function Start-FileSystemWatcher { 

     [CmdletBinding()] 
     param(
     [Parameter()] 
     [string]$Path, 
     [Parameter()] 
     [ValidateSet('Changed','Created','Deleted','Renamed')] 
     [string[]]$EventName, 
     [Parameter()] 
     [string]$Filter, 
     [Parameter()] 
     [System.IO.NotifyFilters]$NotifyFilter, 
     [Parameter()] 
     [switch]$Recurse, 
     [Parameter()] 
     [scriptblock]$Action 
    ) 

     #region Build FileSystemWatcher 

     $FileSystemWatcher = New-Object System.IO.FileSystemWatcher 
     if (-not $PSBoundParameters.ContainsKey('Path')) { 
     $Path = $PWD 
     } 
     $FileSystemWatcher.Path = $Path 
     if ($PSBoundParameters.ContainsKey('Filter')) { 
     $FileSystemWatcher.Filter = $Filter 
     } 

     if ($PSBoundParameters.ContainsKey('NotifyFilter')) { 
     $FileSystemWatcher.NotifyFilter = $NotifyFilter 
     } 

     if ($PSBoundParameters.ContainsKey('Recurse')) { 
     $FileSystemWatcher.IncludeSubdirectories = $True 
     } 

     if (-not $PSBoundParameters.ContainsKey('EventName')) { 
     $EventName = 'Changed','Created','Deleted','Renamed' 
     } 

     if (-not $PSBoundParameters.ContainsKey('Action')) { 
     $Action = { 
      switch ($Event.SourceEventArgs.ChangeType) { 
      'Renamed' { 
       $Object = "{0} was {1} to {2} at {3}" -f $Event.SourceArgs[-1].OldFullPath, 
       $Event.SourceEventArgs.ChangeType, 
       $Event.SourceArgs[-1].FullPath, 
       $Event.TimeGenerated 
      } 

      Default { 
       $Object = "{0} was {1} at {2}" -f $Event.SourceEventArgs.FullPath, 
       $Event.SourceEventArgs.ChangeType, 
       $Event.TimeGenerated 
      } 
      } 

      $WriteHostParams = @{ 
      ForegroundColor = 'Green' 
      BackgroundColor = 'Black' 
      Object = $Object 
      } 

      Write-Host @WriteHostParams 
     } 

     } 

     $ObjectEventParams = @{ 
     InputObject = $FileSystemWatcher 
     Action = $Action 

     } 

     foreach ($Item in $EventName) { 
     $ObjectEventParams.EventName = $Item 
     $ObjectEventParams.SourceIdentifier = "File.$($Item)" 
     Write-Verbose "Starting watcher for Event: $($Item)" 
     $Null = Register-ObjectEvent @ObjectEventParams 
     } 

    } 

    $FileSystemWatcherParams = @{ 
     Path = 'X:\share\scripts\ps\converter\input' 
     Recurse = $True 
     NotifyFilter = 'FileName' 
     Verbose = $True 
     Action = { 
     $Item = Get-Item $Event.SourceEventArgs.FullPath 
     $WriteHostParams = @{ 
      ForegroundColor = 'Green' 
      BackgroundColor = 'Black' 
     } 

     $inputFile = "${PWD}\input\$($Item.Name)".trim() 
     $outputFile = "${PWD}\output\$($Item.Name)".trim() 
     $logFile = "${PWD}\log\$($Item.Name).txt" 
     $testLogFile = "${PWD}\log\$($Item.Name)(t).txt" 

     function mp4-Func { 
      Start-Transcript -path $logFile 
      Write-Host "New mp4 file detected..." 
      $convertingFile = New-Object -TypeName System.IO.FileInfo -ArgumentList $inputFile 
      $locked = 1 
      do { 
      [System.IO.FileStream] $fs = $convertingFile.OpenWrite(); 
      if (!$?) { 
       Write-Host "Can't convert yet, file appears to be loading..." 
       sleep 2 
      } 
      else { 
       $fs.Dispose() 
       $locked = 0 
      } 
      } until ($locked -eq 0) 

      Write-Host "File unlocked and ready for conversion." 
      HandBrake 
      Stop-Transcript 
      $WriteHostParams.Object = "Finished converting: $($Item.Name)" 
     } 

     function HandBrake { 
      .\HandBrakeCLI.exe --input "$inputFile" ` 
          --output "$outputFile" ` 
          --format av_mp4 ` 
          --encoder x264 ` 
          --vb 1700 ` 
          --two-pass ` 
          --aencoder copy:aac ` 
          --ab 320 ` 
          --arate 48 ` 
          --mixdown stereo 
     } 

     switch -regex ($Item.Extension) { 
      '\.mp4' { mp4-Func } 
     } 

     Write-Host @WriteHostParams 
     } 

    } 
    @('Created') | ForEach-Object { 
     $FileSystemWatcherParams.EventName = $_ 
     Start-FileSystemWatcher @FileSystemWatcherParams 
    } 

Answer 1

我想你会发现，$ErrorActionPreference只的cmdlet水平影响的错误，而你打非cmdlet的代码有问题。为此，您可能需要一个try/catch结构。

Answer 2

基于Burt_Harris的回答（请提供他对此答案的回答），我更改了“do while”循环，以便它使用try/catch而不是if/else语句。通过使用$ .Exception.Message和$ .Exception.ItemName我能够更好地理解脚本在特定行停止的原因。

工作代码：

Do { 
    Try { 
     [System.IO.FileStream] $fs = $convertingFile.OpenWrite() 
     $fs.Dispose() 
     $locked = 0 
    } 
    Catch { 
     $ErrorMessage = $_.Exception.Message 
     $FailedItem = $_.Exception.ItemName 
     Write-Host $ErrorMessage 
     Write-Host $FailedItem 
     Write-Host "Can't convert yet, file appears to be loading..." 
     sleep 5 
     continue 
    } 
    } until ($locked -eq 0)