built-in:subprocess模块的用法_temp = info[-1].split('.')

可惜了!!!!

之前一直用os.popen/os.system来执行操作系统的命令，很繁琐，今天了解到了subprocess这个模块，感觉很强大，比os.popen/os.system强太多了，学习分享出来。

The subprocess module allows you to spawn new processes, connect to their input/output/error pipes, and obtain their return codes. This module intends to replace several older modules and functions:

该subprocess模块允许您生成新进程，连接到它们的input/output/error 管道，并获取它们的返回代码。该模块旨在替换几个较旧的模块和功能(如：os.system/os.spawn*)

run函数原型：

subprocess.run(args, *, stdin=None, input=None, stdout=None, stderr=None, capture_output=False, shell=False, cwd=None, timeout=None, check=False, encoding=None, errors=None, text=None, env=None, universal_newlines=None)

The recommended approach to invoking subprocesses is to use the run() function for all use cases it can handle. For more advanced use cases, the underlying Popen interface can be used directly.

大多数情况下推荐使用run()方法调用子进程执行操作系统命令。在更高级的使用场景，可以直接使用底层的popen接口. 

所以大多数情况下，只要熟悉run()方法的使用就够了。

Run the command described by args. Wait for command to complete, then return a CompletedProcessinstance.

另，run()函数返回的是一个CompletedProcess实例对象

来自 <https://docs.python.org/3/library/subprocess.html>

subprocess.CompletedProcess

run()方法的返回值, 返回一个CompletedProcess对象，其属性如下：

以下是一些应用实例：

import subprocess
 
 
# 应用subprocess获取设备列表, 相对于之前的写法感觉更方便，注释的是之前的写法
def getdevlist():
    devlist = []
    # connectfile = os.popen('adb devices')
    # list = connectfile.readlines()
    result_list = subprocess.run('adb devices', capture_output=True, encoding='utf-8').stdout.strip().split('\n')
    # for i in range(len(list)):
    for info in result_list:
        # if list[i].find('\tdevice') != -1:
        if info.find('\tdevice') != -1:
            # temp = list[i].split('\t')
            temp = info.split('\t')
            devlist.append(temp[0])
    return devlist
 
 
def main():
    # 打印出结果，但devstr1.stdout为空
    devstr1 = subprocess.run('adb devices')
    print(f'devstr1: {devstr1}')
    # 打印出结果，结果中有捕获stdout/stderr值，但类型为bytes
    devstr2 = subprocess.run('adb devices', capture_output=True)
    print(f'devstr2: {devstr2}')
    # 打印出结果，结果中有捕获stdout/stderr值，类型为str, 因为有指定encoding=‘utf-8'
    devstr3 = subprocess.run('adb devices', capture_output=True, encoding='utf-8')
    print(f'devstr3: {devstr3}')
    # 打印出结果，结果中有捕获stdout值，类型为str, 因为有指定encoding=‘utf-8'
    devstr4 = subprocess.run('adb devices', stdout=subprocess.PIPE, encoding='utf-8')
    print(f'devstr4: {devstr4}')
    # 打印出结果，结果中有捕获stdout/stderr值，类型为str, 因为有指定encoding=‘utf-8', 此时不再再设置capture_output=True
    devstr5 = subprocess.run('adb devices', stderr=subprocess.PIPE, stdout=subprocess.PIPE, encoding='utf-8')
    print(f'devstr5: {devstr5}')
 
    print(f'当前Pc连接的设备如下：\n{getdevlist()}')
 
 
if __name__ == '__main__':
    main()

-----------the result of pycharm---------------------------------------------------
List of devices attached
ad17caf5	device
 
devstr1: CompletedProcess(args='adb devices', returncode=0)
devstr2: CompletedProcess(args='adb devices', returncode=0, stdout=b'List of devices attached\r\nad17caf5\tdevice\r\n\r\n', stderr=b'')
devstr3: CompletedProcess(args='adb devices', returncode=0, stdout='List of devices attached\nad17caf5\tdevice\n\n', stderr='')
devstr4: CompletedProcess(args='adb devices', returncode=0, stdout='List of devices attached\nad17caf5\tdevice\n\n')
devstr5: CompletedProcess(args='adb devices', returncode=0, stdout='List of devices attached\nad17caf5\tdevice\n\n', stderr='')
当前Pc连接的设备如下：
['ad17caf5']
 
Process finished with exit code 0