Powershell Example: Environment Variables

Function GetEnvVar{

    param(

        [Parameter(Mandatory=$true)][String]$varname

    )

    $val = [System.Environment]::GetEnvironmentVariable("$varname", "Machine")

    if (!$val){

        Log "$varname env variable not found!"

        return ""

    }

    Log "$varname env variable found: $val"

    return $val

}

Function SetEnvVar{

    param(

        [Parameter(Mandatory=$false)][String]$envname,

        [Parameter(Mandatory=$false)][String]$envval

    )

    $beforeval = GetEnvVar $envname

    Log "Before change ${envname}: $beforeval"
    [System.Environment]::SetEnvironmentVariable($envname,$envval,[System.EnvironmentVariableTarget]::Machine)
    $afterval = GetEnvVar $envname

    Log "After change ${envname}: $afterval"

}
Function UpdateEnvVar{

    param(

        [Parameter(Mandatory=$true)][String]$envname,

        [Parameter(Mandatory=$true)][String]$newVal

    )
    $tmpenv = GetEnvVar $envname

    if ($tmpenv -eq $newVal){

        Log "$envname already set to $newval"

    }else{

        SetEnvVar $envname $newVal

    }

}
Function UpdateCLASSPATH{

    param(

        [Parameter(Mandatory=$true)][String]$oldpath,

        [Parameter(Mandatory=$true)][String]$newpath

    )

    $tmpcp = GetEnvVar $CLASSPATH

    if ($tmpcp -like "*${oldpath}*"){

        $newcp = $tmpcp.Replace($oldpath, $newpath)

        SetEnvVar $CLASSPATH $newcp

    }else{

        Log "CLASSPATH already contains $newpath"

    }

}