Create Zip File from Piped Files

##############################################################################
##
## New-ZipFile
##
## From Windows PowerShell Cookbook (O'Reilly)
## by Lee Holmes (http://www.leeholmes.com/guide)
##
##############################################################################

<#

.SYNOPSIS

Create a Zip file from any files piped in.

.EXAMPLE

PS > dir *.ps1 | New-ZipFile scripts.zip
Copies all PS1 files in the current directory to scripts.zip

.EXAMPLE

PS > "readme.txt" | New-ZipFile docs.zip
Copies readme.txt to docs.zip

#>

param(
    ## The name of the zip archive to create
    $Path = $(throw "Specify a zip file name"),

    ## Switch to delete the zip archive if it already exists.
    [Switch] $Force
)

Set-StrictMode -Version 3

## Create the Zip File
$zipName = $executionContext.SessionState.`
    Path.GetUnresolvedProviderPathFromPSPath($Path)

## Check if the file exists already. If it does, check
## for -Force - generate an error if not specified.
if(Test-Path $zipName)
{
    if($Force)
    {
        Remove-Item $zipName -Force
    }
    else
    {
        throw "Item with specified name $zipName already exists."
    }
}

## Add the DLL that helps with file compression
Add-Type -Assembly System.IO.Compression.FileSystem

try
{
    ## Open the Zip archive
    $archive = [System.IO.Compression.ZipFile]::Open($zipName, "Create")

    ## Go through each file in the input, adding it to the Zip file
    ## specified
    foreach($file in $input)
    {
        ## Skip the current file if it is the zip file itself
        if($file.FullName -eq $zipName)
        {
            continue
        }

        ## Skip directories
        if($file.PSIsContainer)
        {
            continue
        }

        $item = $file | Get-Item
        $null = [System.IO.Compression.ZipFileExtensions]::CreateEntryFromFile(
            $archive, $item.FullName, $item.Name)
    }
}
finally
{
    ## Close the file
    $archive.Dispose()
    $archive = $null
}