如何在PowerShell脚本中用copy /b批量给指定文件加BOM并改扩展名

Great question, and I totally get why the standard solutions aren't working for you—those encoding and cross-version compatibility issues are tricky. Here's a solid, reliable solution that meets all your requirements:

First, let's recap the key constraints we need to work around:

• Can't use cat or >> because they mess up UTF8-BOM encoding
• Set-Content is inconsistent across PowerShell versions (no BOM by default in v6+, configuration-dependent in older versions)
• Need to loop through DIL_BG_TXN*.dat files, prepend the BOM marker, and output to matching .txt files

Solution Script #

This PowerShell script uses binary copy to preserve encoding integrity, handles file traversal, and renames outputs correctly:

# Set your target directory here (update to your actual path)
$targetDirectory = "C:\Your\File\Directory"

# Get all .dat files matching the specified pattern
$datFiles = Get-ChildItem -Path $targetDirectory -Filter "DIL_BG_TXN*.dat" -File

# Path to your BOM marker file (adjust if it's stored elsewhere)
$bomMarkerPath = Join-Path -Path $targetDirectory -ChildPath "BOMMarker.txt"

# Process each matched file
foreach ($file in $datFiles) {
    # Create output filename by replacing .dat extension with .txt
    $outputFilePath = [System.IO.Path]::ChangeExtension($file.FullName, ".txt")
    
    # Execute binary copy to prepend the BOM marker to the .dat file
    copy /b "$bomMarkerPath"+"$($file.FullName)" "$outputFilePath"
    
    # Optional: Print progress message
    Write-Host "Processed: $($file.Name) -> $([System.IO.Path]::GetFileName($outputFilePath))"
}

Why This Works #

• Binary Copy (copy /b): This command concatenates raw bytes, so the UTF8-BOM from BOMMarker.txt is added correctly without altering the original .dat file's content or encoding. It works consistently across all PowerShell versions, no configuration dependencies.
• Pattern-Based Traversal: Get-ChildItem efficiently finds all files matching your DIL_BG_TXN*.dat pattern in the target directory.
• Safe Extension Rename: Using [System.IO.Path]::ChangeExtension is a robust way to swap extensions without error-prone manual string edits.

To clarify why this isn't a duplicate question:

• Most related answers don't combine pattern-based file traversal with binary concatenation and extension renaming
• They often rely on text-based commands that break UTF8-BOM encoding requirements
• None account for the cross-version PowerShell compatibility you need

内容的提问来源于stack exchange，提问作者rmcsharry