Split-Csv3.ps1

<#
    .SYNOPSIS
    Splits .CSV file into parts.
#>
param (
        [parameter(
            Mandatory = $true
        )]
        [string]
        # File name to split
    $FileName,
        [parameter(
            Mandatory = $true
        )]
        [Int64]
        # Number of lines in one part.
    $Lines,
        [int]
        # Number of Header line.  The lines before are not used.  Setting it to 0 means no header in splitted parts
    $Head = 1
)

$file = Get-Item $FileName
$part = 0

if ($Head) {
    $Header = Get-Content $file.FullName -Head $Head | Select-Object -Last 1
}

Get-Content $file.FullName -ReadCount $Lines | ForEach-Object {
    $part++
    $newName = Join-Path -Path $file.DirectoryName -ChildPath ($file.BaseName + $part + $file.Extension)

    if ($Head -and ($part -gt 1)) {
        Set-Content -Path $newName -Value $Header 
    }
    Write-Verbose -Message ('Saving file: {0}' -f $newName)
    Add-Content -Path $newName -Value $_
}