set proxy environment variable

proxy.ps1

# Set-ExecutionPolicy -ExecutionPolicy Unrestricted
$proxy_host = "http://192.168.5.2"
$proxy_port = 36000
$before_path = Get-Location

function remove-env($name) {
    $before= Get-Location
    try {
        # https://stackoverflow.com/questions/8388650/powershell-how-can-i-stop-errors-from-being-displayed-in-a-script
        Set-Location Env:
        Remove-Item $name -ErrorAction Stop | Out-Null
    } catch {} finally {
        Set-Location $before
    }
}

remove-env "http_proxy"
remove-env "https_proxy"
remove-env "no_proxy"
remove-env "HTTP_PROXY"
remove-env "HTTPS_PROXY"
remove-env "NO_PROXY"

$env:HTTP_PROXY = "${proxy_host}:${proxy_port}"
$env:HTTPS_PROXY = "${proxy_host}:${proxy_port}"
# https://en.wikipedia.org/wiki/Reserved_IP_addresses
$env:NO_PROXY = "localhost,127.0.0.1,127.0.0.0/8,192.168.0.0/16,10.0.0.0/8,172.16.0.0/12"

unproxy.ps1

function remove-env($name) {
    $before= Get-Location
    try {
        # https://stackoverflow.com/questions/8388650/powershell-how-can-i-stop-errors-from-being-displayed-in-a-script
        Set-Location Env:
        Remove-Item $name -ErrorAction Stop | Out-Null
    } catch {} finally {
        Set-Location $before
    }
}

remove-env "http_proxy"
remove-env "https_proxy"
remove-env "no_proxy"
remove-env "HTTP_PROXY"
remove-env "HTTPS_PROXY"
remove-env "NO_PROXY"