Linux中的标准输入输出
https://blog.csdn.net/zhongqi2513/article/details/78613768
>/dev/null 2>&1和2>&1 >/dev/null区别根本分析
https://blog.csdn.net/a1439458305/article/details/79586567
https://blog.csdn.net/zhongqi2513/article/details/78613768
https://blog.csdn.net/a1439458305/article/details/79586567