ファイルのチェックサムを取得するPowerShellスクリプト for PowerShell 3.0

Get-Checksum.ps1

# Get-Checksum.ps1: File Checksum Integrity Verifier
Param(
    [string] $filename,
    [string] $algorithm = ( 'sha1' ),
    [switch] $help
)
 
 
Function Calc-Hash
{
    $fileStream = [system.io.file]::openread( ( resolve-path $filename ) )
    $hash = [System.Security.Cryptography.HashAlgorithm]::create( $algorithm ).ComputeHash( $fileStream )
    $fileStream.close()
    $fileStream.dispose()
    $value = [System.BitConverter]::ToString( $hash ).Replace( "-", "" ).ToLower()
 
    Write-Host "$value  $filename"
}
 
 
Function View-Help
{
    Write-Host "Usage: Get-Checksum [OPTION]... [FILE]...
Print or check checksums.
 
OPTIONS:
    -a, -algorithm    md5, sha1, sha256, sha384, sha512, mactripledes, ripemd160
    -h, -help         Display this help.
 
EXAMPLES:
    Get-Checksum filename.zip
    Get-Checksum -a md5 filename.zip
"
}
 
 
Function Get-Options
{
    If( $help ) {
        View-Help
    } elseif( !$filename ) {
        Write-Host "Missing filename. (`"Get-Checksum -help`" )"
    } else {
        Calc-Hash
    }
}
 
 
Get-Options