python3 十二、执行command

我们在使用的时候也经常需要调用其他程序
例如:在app自动化时我们要获取手机的uuid和version,以及启用appium server
这时就用到了我们subprocess库
库里面有很多的函数方法本篇博文就不做细细解释了
只说几个我们常用的方法
首先是popen类,这个类是将command放在新进程的子进程执行

"""
Execute a child program in a new process.

    For a complete description of the arguments see the Python documentation.

    Arguments:
      args: A string, or a sequence of program arguments.  # 字符串类型或者序列(tuple\list)

      bufsize: supplied as the buffering argument to the open() function when
          creating the stdin/stdout/stderr pipe file objects  # 缓冲

      executable: A replacement program to execute.

      stdin, stdout and stderr: These specify the executed programs' standard
          input, standard output and standard error file handles, respectively.  # 一般使用subprocess.PIPE比较多,该模式的意思是打开通向标准流的管道

      preexec_fn: (POSIX only) An object to be called in the child process
          just before the child is executed.

      close_fds: Controls closing or inheriting of file descriptors.

      shell: If true, the command will be executed through the shell.  # 当args为字符串时,shell=True

      cwd: Sets the current directory before the child is executed.

      env: Defines the environment variables for the new process.

      text: If true, decode stdin, stdout and stderr using the given encoding
          (if set) or the system default otherwise.

      universal_newlines: Alias of text, provided for backwards compatibility.

      startupinfo and creationflags (Windows only)

      restore_signals (POSIX only)

      start_new_session (POSIX only)

      pass_fds (POSIX only)

      encoding and errors: Text mode encoding and error handling to use for
          file objects stdin, stdout and stderr.

    Attributes:
        stdin, stdout, stderr, pid, returncode
"""

Popen().communicate方法用于与执行的程序做交互,返回(stdout, stderr)元组
stdout为正常输出,stderr为错误输出

获取设备UUID和version 封装好的实例

import subprocess


class Command:

    def __cmd_run(self, command):
        try:
            out, err = \
                subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True).communicate()
            out = str(out, encoding="utf8").strip()
            err = str(err, encoding="uft8").strip()
            if err:
                raise Exception("run command error {}".format(err))
        except:
            raise
        else:
            return out

    def devices_and_version(self):
        devices_uuid = self.__get_devices()
        versions = self.__get_version()
        res = list(zip(devices_uuid, versions))
        return res

    def __get_devices(self):
        command = "adb devices"
        res = self.__cmd_run(command)
        if "\r\n" in res:  # windows newline == \r\n
            res = res.split("\r\n")
        if "\n" in res:  # linux newline == \n
            res = res.split("\n")
        res.remove("List of devices attached")
        devices = []
        for item in res:
            if "device" in item:
                device = item.split("\t")[0]
                devices.append(device)
        return devices

    def __get_version(self):
        uuids = self.__get_devices()
        command = "adb -s {} shell getprop ro.build.version.release"
        versions = []
        for uuid in uuids:
            version = self.__cmd_run(command.format(uuid))
            versions.append(version)
        return versions

https://www.jianshu.com/p/af5c6b1104d8 结合看更佳