print (os.environ["TEMP"])

mydir = "c:\\mydir"
os.environ["MYDIR"] = mydir
print (os.environ["MYDIR"])

pathV = os.environ["PATH"]
print (pathV)
os.environ["PATH"]= mydir + ";" + os.environ["PATH"]
print (os.environ["PATH"])

class MyEnv:

? def __init__(self):
??? self.envFile = "c:\\myenv.txt"
??? self.envs = {}
?
? def SetEnvFile(self, filename) :
??? self.envFile = filename
???????
? def Save(self) :
??? outf = open(self.envFile, "w")
??? if not outf:
????? print ("env file cannot be opened for write!")
??? for k, v in self.envs.items() :
????? outf.write(k + "=" + v + "\n")
??? outf.close()
???
? def Load(self) :
??? inf = open(self.envFile, "r")
??? if not inf:
????? print ("env file cannot be opened for open!")
??? for line in inf.readlines() :
????? k, v = line.split("=")
????? self.envs[k] = v
??? inf.close()
???
? def ClearAll(self) :
??? self.envs.clear()
???
? def AddEnv(self, k, v) :
??? self.envs[k] = v
???
? def RemoveEnv(self, k) :
??? del self.envs[k]
???
? def PrintAll(self) :
??? for k, v in self.envs.items():
????? print ( k + "=" + v )
??
if __name__ == "__main__" :
? myEnv = MyEnv()
? myEnv.SetEnvFile("c:\\myenv.txt")
? myEnv.Load()
? myEnv.AddEnv("MYDIR", "c:\\mydir")
? myEnv.AddEnv("MYDIR2", "c:\\mydir2")
? myEnv.AddEnv("MYDIR3", "c:\\mydir3")
? myEnv.Save()
? myEnv.PrintAll()