- exit 退出程序 - continue 进行下一次循环 - break 退出循环 - shift 输入参数位移 ``` #! /bin/env bash sum=0 for i do let sum+=$i done echo $sum ``` ``` #! /bin/env bash sum=0 while [ $# -ne 0 ] do let sum+=$1 shift done echo $sum ``` ``` #! /bin/env bash sum=0 while [ $# -ne 0 ] do let sum+=$1 shift 2 done echo $sum ```