python 调用系统命令os

一、获取环境变量

import os

env_dist = os.environ
# 打印所有环境变量，遍历字典
for key in env_dist:
    print key + ' : ' + env_dist[key]

二、os.system(cmd)与os.popen(cmd)的区别

os.system(cmd)返回结果为0（成功） 1,2

os.popen(cmd)返回系统执行命令的结果

Python 2.7.12 (default, Oct  8 2019, 14:14:10) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.system('nvidia-smi -L')
GPU 0: GeForce GTX 1080 (UUID: GPU-4e2ee1df-6a5b-31b7-f18c-adb475dd62c8)
0
>>> os.popen('nvidia-smi -L')
<open file 'nvidia-smi -L', mode 'r' at 0x7fa9f59ff540>
>>> os.popen('nvidia-smi -L').readlines()
['GPU 0: GeForce GTX 1080 (UUID: GPU-4e2ee1df-6a5b-31b7-f18c-adb475dd62c8)\n']
>>> os.popen('nvidia-smi -L').readlines()[0]
'GPU 0: GeForce GTX 1080 (UUID: GPU-4e2ee1df-6a5b-31b7-f18c-adb475dd62c8)\n'

三、调用环境变量获取GPU序列号

>>> os.popen('A=$(nvidia-smi -L) &&  B=${A##*GPU} &&  C=${B%%)*+} && echo $C').readlines()[0]
'-4e2ee1df-6a5b-31b7-f18c-adb475dd62c8)\n'