python_shell.py

# coding=utf-8

import shlex
import datetime
import subprocess
import time


def execute_command(cmdstring, cwd=None, timeout=None, shell=False):
    """
    执行一个SHELL命令
    封装了subprocess的Popen方法, 支持超时判断，支持读取stdout和stderr
    :param cmdstring: shell命令字符串
    :param cwd: 运行命令时更改路径，如果被设定，子进程会直接先更改当前路径到cwd
    :param timeout: 超时时间，秒，支持小数，精度0.1秒
    :param shell: 是否通过shell运行
    :return: return_code
    :raise: Exception: 执行超时
    """
    if shell:
        cmdstring_list = cmdstring
    else:
        cmdstring_list = shlex.split(cmdstring)
    if timeout:
        end_time = datetime.datetime.now() + datetime.timedelta(seconds=timeout)

    # 没有指定标准输出和错误输出的管道，因此会打印到屏幕上；
    sub = subprocess.Popen(cmdstring_list, cwd=cwd, stdin=subprocess.PIPE, shell=shell, bufsize=4096)

    # subprocess.poll()方法：检查子进程是否结束了，如果结束了，设定并返回码，放在subprocess.returncode变量中
    while sub.poll() is None:
        time.sleep(0.1)
        if timeout:
            if end_time <= datetime.datetime.now():
                raise Exception("Timeout：%s" % cmdstring)

    return str(sub.returncode)


if __name__ == "__main__":
    while True:
        cmd = "cat /opt/lsx/test.log >> /opt/lsx/test2.log"
        execute_command(cmdstring=cmd, shell=True)
        time.sleep(10)