当我们在终端中直接执行命令（如python data_process.py、ping baidu.com）时，启动的进程默认是前台进程，其具有以下特点： 占据终端输入输出：前台进程会独占终端的标准输入（stdin）、标准输出（stdout）和标准错误（stderr）。例如，执行ping baidu.com后，终端会持续输出 ping ...

There is little worse as a developer than trying to figure out why an application is not working if you don’t know what is going on inside it. Sometimes you can’t even tell whether the system is ...