subprocess.Popen stdout重定向內容實時獲取

python 打開一個新進程執行系統命令， test 執行完才能獲取返回， test1 實時獲取返回結果

import subprocess

def test(cmd):
    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
    lines = p.stdout.readlines()
    for line in lines:
        tmp = line.decode('gbk').strip()
        print(tmp)

def test1(cmd):
    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
    for i in iter(p.stdout.readline, ''):
        if len(i) < 1:
            break
        print(i.decode('gbk').strip())

if __name__ == '__main__':
    test("ping www.baidu.com")
    test1("ping www.baidu.com")