Split-Join-Files.ps1

# http://stackoverflow.com/questions/4533570/in-powershell-how-do-i-split-a-large-binary-file

# NOTE
# both fucntions do not check to see if a file already exists, so if you are splitting or joining and the resulting file already exists, it's goinng to be overwritten.

# TODO
# script requires full path - does not work with relative paths like ".\some\sub\file.txt"
# fix note above on split-file by checking first to see if part file name exists, then error out or add parameter for -force
# fix note above on join-file by adding "-1" etc to file name if it already exists
# change write-host to write-verbose
# include option to specify number of desired parts (each part size would be totalsize/#ofdesiredparts)
# maybe include in each file name the total number of expected files? so you know if some are missing

# specify file name and size of each part (5mb)
# new files are like:
# c:\temp\file.txt.part1
function Split-File ([string]$inFile, [int]$bufSize = 5mb) {
    $stream = [System.IO.File]::OpenRead($inFile)
    $chunkNum = 1
    $barr = New-Object byte[] $bufSize

    $fileinfo = [System.IO.FileInfo]$inFile
    $name = $fileinfo.Name
    $dir = $fileinfo.Directory

    while ($bytesRead = $stream.Read($barr, 0, $bufsize)) {
        $outFile = Join-Path $dir "$name.part$chunkNum"
        $ostream = [System.IO.File]::OpenWrite($outFile)
        $ostream.Write($barr, 0, $bytesRead)
        $ostream.Close()
        Write-Host "Wrote $outFile"
        $chunkNum += 1
    }
    $stream.Close()
}

# all split files must be in same directory
# specify a part file without number like:
# c:\temp\file.txt.part
function Join-File ([string]$infilePrefix) {
    $fileinfo = [System.IO.FileInfo]$infilePrefix
    $outFile = Join-Path $fileinfo.Directory $fileinfo.BaseName
    $ostream = [System.Io.File]::OpenWrite($outFile)
    $chunkNum = 1
    $infileName = "$infilePrefix$chunkNum"

    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()
}