主要用到两个命令 -n -z if [ -n "$PID" ]; then echo "PID is not empty" fi if[ -z "$PID" ]; then echo "PID is empty" fi 相关文章: 2022-12-23 2021-12-04 2021-12-04 2022-02-08 2021-07-24 2022-12-23 2022-12-23 2021-12-04