GetEnvironmentVariable() and SetEnvironmentVariable() for PATH Variable

Question

I want to extend the current PATH variable with a C# program. Here I have several problems:

1. Using GetEnvironmentVariable(\"PATH\", EnvironmentVariable

Answer 1

You can use the registry to read and update:

string keyName = @"SYSTEM\CurrentControlSet\Control\Session Manager\Environment";
//get non-expanded PATH environment variable            
string oldPath = (string)Registry.LocalMachine.CreateSubKey(keyName).GetValue("Path", "", RegistryValueOptions.DoNotExpandEnvironmentNames);

//set the path as an an expandable string
Registry.LocalMachine.CreateSubKey(keyName).SetValue("Path", oldPath + ";%MYDIR%",    RegistryValueKind.ExpandString);