Powershell script to generate UNIX diff

cmdiff.ps1

param (
    [Parameter(Mandatory=$true)][string]$SrcRev,
    [Parameter(Mandatory=$true)][string]$DstRev,
    [bool]$Force
)

function ExtractFileNameFromRev([string]$rev)
{
    if ("$rev" -match '^([^:#@]*:)?([^@]*).*$')
    {
        $matches[2]
        return
    }
    echo "UNKNOWN"
}

function FileExists([string]$File)
{
    if ("$File")
    {
        Test-Path -LiteralPath "$File"
        return
    }
    $false
}

$srcLabel = ExtractFileNameFromRev "$SrcRev"
$dstLabel = ExtractFileNameFromRev "$DstRev"

$srcPath = [io.path]::combine($env:Temp, [guid]::NewGuid())
$dstPath = [io.path]::combine($env:Temp, [guid]::NewGuid())

cm cat "$SrcRev;$srcPath" "$DstRev;$dstPath"
if ($Force -or (FileExists "$srcPath" -and FileExists "$dstPath"))
{
    # Download diff and depencencies at http://gnuwin32.sourceforge.net/packages/diffutils.htm
    diff -Naur --label "$srcLabel" --label "$dstLabel" "$srcPath" "$dstPath"
}
else
{
    echo "Unable to calculate differences"
}

rm -Force "$srcPath","$dstPath" -ErrorAction SilentlyContinue