Python subprocess + timeout的命令执行

import time  
import subprocess  
  
class TimeoutError(Exception):  
    pass  
  
def command(cmd, timeout=60):  
    """执行命令cmd，返回命令输出的内容。 
    如果超时将会抛出TimeoutError异常。 
    cmd - 要执行的命令 
    timeout - 最长等待时间，单位：秒 
    """  
    p = subprocess.Popen(cmd, stderr=subprocess.STDOUT, stdout=subprocess.PIPE, shell=True)  
    t_beginning = time.time()  
    seconds_passed = 0  
    while True:  
        if p.poll() is not None:  
            break  
        seconds_passed = time.time() - t_beginning  
        if timeout and seconds_passed > timeout:  
            p.terminate()  
            raise TimeoutError(cmd, timeout)  
        time.sleep(0.1)  
    return p.stdout.read()  
  
if __name__ == "__main__":  
    print command(cmd=‘ping www.redicecn.com‘, timeout=1)