shell循环

for循环基本语法

#语法1
for 变量 in 值1 值2 值3 ...
do
    代码
done

#语法2
for((初始值;循环条件;变量变化))
do
    代码
done

for循环案例

[root@CentOS01 shcode]# vim testFor.sh

#!/bin/bash
#案例1：打印命令行输入的所有参数
for i in "$@"
do
        echo "num is $i"
done

#案例2：求1到100的和
SUM=0
for ((i=1; i<=10; i++))
do
        SUM=$[ $SUM + $i ]
done
echo "SUM is $SUM"


[root@CentOS01 shcode]# sh testFor.sh 1 2 3 54
num is 1
num is 2
num is 3
num is 54
SUM is 55

while循环基本语法

while [ 条件判断式 ]
do
    代码
done

while循环案例

[root@CentOS01 shcode]# vim testWhile.sh

#!/bin/bash
#案例1：从命令行输入一个数n，统计1到n的累加
SUM=0
i=0
while [ $1 -gt $i ]
do
        i=$[ $i + 1 ]
        SUM=$[ $i + $SUM ]
done
echo "SUM is $SUM"


[root@CentOS01 shcode]# sh testWhile.sh 10
SUM is 55