import os 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"])

import os 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()