example:
Python 2.7.13 (v2.7.13:a06454b1afa1, Dec 17 2016, 20:53:40) [MSC v.1500 64 bit (AMD64)] on win32Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> cmd = 'adb devices'
>>> dis1 = os.system(cmd)
List of devices attached
HEE6R15617005387 device
>>> dis1
0
>>> dis2 = os.popen(cmd)
>>> dis2
<open file 'adb devices', mode 'r' at 0x00000000024AC150>
>>> dis2.read()
'List of devices attached\nHEE6R15617005387\tdevice\n\n'
>>>
由此可见：
os.system(cmd) # os.system() 屏幕输出无法捕获
display = os.popen(cmd) #os.popen()输出可捕获成文件
