I am running python 3.9 on Windows.

```
print(sys.path)
currDir = os.getcwd()
currDir += "\node"

sys.path.append(currDir)
print(sys.path)

```

I see the 2nd print out of `sys.path` has my `c:\working\node\`

But my issue is when I run the command under `c:\working\node\`, e.g. `npm install`

```
p = subprocess.Popen(["npm.cmd", "install]),

```

I get error saying 'The system cannot find the file specified'

And after my script is run , I try 'echo %PATH%', I don't see `c:\working\node\` in the %PATH% varaible too?

Can you please tell me how can I add a new directory to system path variable so that `subprocess.Popen` can see the new addition?