使用os.environ来读取和修改环境变量：

复制代码 代码如下:
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"])

自定义的python的环境变量类：

复制代码 代码如下:
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()