for 實現：
代碼如下:
#!/bin/bash
set i=0
set j=0
for((i=0;i<10;))
do
        let "j=j+1"
        echo "-------------j is $j -------------------"
done

while實現：
代碼如下:
#!/bin/bash
set j=2
while true
do
        let "j=j+1"
        echo "----------j is $j--------------"
done