CMD

set http_proxy=http://127.0.0.1:7890
set https_proxy=http://127.0.0.1:7890

Powershell

$env:http_proxy = "http://127.0.0.1:7890"
$env:https_proxy = "http://127.0.0.1:7890"

Linux

export http_proxy=http://127.0.0.1:7890
export https_proxy=http://127.0.0.1:7890