PowerShell脚本追加文件时遇被占用错误的解决方法

问题场景 #

编写PowerShell脚本从JSON文件提取指定数据并追加到.txt文件，执行初始代码时出现大量文件占用错误，导致导出数据截断。

初始代码：

$columns = "ID_Report","Name","Created_by","Last_mod_by"

$file = Get-Content -Path "W:\Personal\Ulrich\VA-Scraping\reports.json" -Raw | ConvertFrom-Json

$key_first = "items"

Write-Output "$($columns[0]);$($columns[1]);$($columns[2]);$($columns[3]);$($columns[4])" > xxx.txt

foreach ($record in $file){
    if ($record | Select-Object -ExpandProperty $key_first -ErrorAction SilentlyContinue){ 
        foreach ($item in $record.items){
            "$($item.id);$($item.name);$($item.createdBy);$($item.modifiedBy)" | Add-Content "W:\Personal\Ulrich\Skriptiky\xxx.txt" 
        }
    }

}

错误信息 #

Add-Content : The process cannot access the file 'W:\Personal\Ulrich\Skriptiky\xxx.txt' because it is being used by another process.
At line:12 char:82
+ ... tem.modifiedBy)" | Add-Content "W:\Personal\Ulrich\Skriptiky\xxx.txt"
+                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : WriteError: (W:\Personal\Ulrich\Skriptiky\xxx.txt:String) [Add-Content], IOException
    + FullyQualifiedErrorId : GetContentWriterIOError,Microsoft.PowerShell.Commands.AddContentCommand

解决方案 #

调整代码后问题得到解决，优化后的代码如下：

$columns = "ID_Report","Name","Created_by","Last_mod_by"

$file = Get-Content -Path "W:\Personal\Ulrich\Skriptiky\VA-Scraping\reports.json" -Raw | ConvertFrom-Json
$outfile = "W:\Personal\Ulrich\Skriptiky\VA-Scraping\vystupy\$(Get-Date -f yyyyMMdd).txt"

$key_first = "items"

Write-Output "$($columns[0]);$($columns[1]);$($columns[2]);$($columns[3]);$($columns[4])" | Out-File -FilePath $outfile

$file | ForEach-Object {$_.items } | ForEach-Object {Write-Output "$($_.id);$($_.name);$($_.createdBy);$($_.modifiedBy)"} |  Add-Content "$outfile"

优化要点 #

• 用统一变量$outfile管理输出路径，避免路径不一致引发的潜在问题
• 改用管道式ForEach-Object替代嵌套foreach循环，减少文件频繁打开/关闭操作，降低文件被占用的概率
• 输出文件名加入日期戳，避免重复执行时覆盖原有文件

内容的提问来源于stack exchange，提问作者Tomáš Ulrich