Python: Existing environment variables which need to be added again to execute

I'm trying to execute a command which runs a program that uses perl and python. Although both of them are already in PATH, I get this error 'perl' is not recognized as an internal or ex开发者_如何学编程ternal command,operable program or batch file. 'python' is not recognized as an internal or external command,operable program or batch file. So I tried os.putenv('PATH', dir) but only one was taken in.

So try

os.putenv('PATH', dir + ";" + otherdir)