1.循环介绍

循环就是迭代(重复)一些命令的代码块，如果循环控制条件不满足的话，就结束循环

2.for循环语法

for 循环控制条件

do

commands

done

#当“循环控制条件”不满足条件，结束for循环

3.for循环样例

[root@kibana ~]# cat for-1.sh 
#!/bin/bashfor planet in "Mercury 1" "Venus 3" "Earth 5" "Mars 7" "Jupiter 9"
doset -- $planet#解析变量"planet"并且设置位置参数echo "$1  $2,000,000 miles from the sun"
doneexit 0
[root@kibana ~]# sh for-1.sh 
Mercury  1,000,000 miles from the sun
Venus  3,000,000 miles from the sun
Earth  5,000,000 miles from the sun
Mars  7,000,000 miles from the sun
Jupiter  9,000,000 miles from the sun
[root@kibana ~]# 

[root@kibana ~]# cat for-2.sh 
#!/bin/bashs=0
for (( i=1; i<=100; i=i+1 ))
dos=$(($s+$i))
done
echo "The result of '1+2+3...+100' is  ==> $s"
[root@kibana ~]# sh for-2.sh 
The result of '1+2+3...+100' is  ==> 5050
[root@kibana ~]#