In Powershell, How do I split a large binary file?

Question

I've seen the answer elsewhere for text files, but I need to do this for a compressed file.

I've got a 6G binary file which needs to be split into 100M chunks. Am I missing the analog for unix's "head" somewhere?

Answer 1

Never mind. Here you go:

function split($inFile,  $outPrefix, [Int32] $bufSize){

  $stream = [System.IO.File]::OpenRead($inFile)
  $chunkNum = 1
  $barr = New-Object byte[] $bufSize

  while( $bytesRead = $stream.Read($barr,0,$bufsize)){
    $outFile = "$outPrefix$chunkNum"
    $ostream = [System.IO.File]::OpenWrite($outFile)
    $ostream.Write($barr,0,$bytesRead);
    $ostream.close();
    echo "wrote $outFile"
    $chunkNum += 1
  }
}

Assumption: bufSize fits in memory.

Answer 2

The answer to the corollary question: How do you put them back together?

function stitch($infilePrefix, $outFile) {

    $ostream = [System.Io.File]::OpenWrite($outFile)
    $chunkNum = 1
    $infileName = "$infilePrefix$chunkNum"

    $offset = 0

    while(Test-Path $infileName) {
        $bytes = [System.IO.File]::ReadAllBytes($infileName)
        $ostream.Write($bytes, 0, $bytes.Count)
        Write-Host "read $infileName"
        $chunkNum += 1
        $infileName = "$infilePrefix$chunkNum"
    }

    $ostream.close();
}