shell基础，原来脚本并不难！

------一个小计算器-----

#!/bin/bash #this

read -p "请输入第一个整数：" ONE read -p "请输入第二个整数：" TWO read -p "请输入运算符：" TH echo "$ONE$TH$TWO=$(($ONE $TH $TWO))"

---------一个IF单分支语句-----

#!/bin/bash #this

read -p "输入目录：" DIR if [ ! -d $DIR ] then mkdir -p $DIR fi

echo "Done"

---------一个IF双分支语句---

#!/bin/bash #this

ping -c1 -i0.1 -W1 $1

if [ $? -eq 0 ] then echo "$1 is UP!" else echo "$1 is DOWN!" fi

=================if 嵌套================ #！/bin/bash

read -p "请输入你的成绩：" A if [ $A -le 10 ] then echo "恭喜进入决赛" read -p "请输入性别(boy/girl)：" SEX if [ $SEX = boy ] then echo "进入男子组" else echo "进入女子组" fi else echo "很遗憾，你被淘汰" fi

-------以下是CASE语句----------

#!/bin/bash #this export LC_ALL=C //区分大小写

read -p "请输入字符：" KEY

case $KEY in

    [A-Z] )
            echo "您输入的$KEY是大写字母。"
    ;;
    [a-z] )
            echo "您输入的$KEY是小写字母。"
    ;;
    [0-9] )
            echo "您输入的$KEY是数字。"
    ;;
    ,)
            echo "您输入的是$KEY。"
    ;;
    "#")
            echo "您输入的是$KEY。"
    ;;
    *)
            echo "您输入的是其它字符。"
    ;;

esac

-----------------以下是函数------------------ #!/bin/bash sum(){ read -p "请输入第一个整数：" NUM1 read -p "请输入第二个整数：" NUM2 echo "你输入的两个数为：$NUM1和$NUM2。" SUM=$(($NUM1+$NUM2)) echo "两个数的和是：$SUM" #return $(($NUM1+$NUM2)) //使用返回值的方法，最大不可以大于255 } sum #echo "两个数的和是：$?"

---------以下是FOR循环----------------

for IP in 192.168.80.{5..183} do ping -c1 -i0.2 -W1 $IP &> /dev/null if [ $? -eq 0 ] then echo "$IP is UP!" else echo "$IP is down!" fi done

----------以下是例子------------

#!/bin/bash

for USER in test{1..10} do useradd $USER echo "${USER}abc" | passwd --stdin $USER &> /dev/null done

cat /etc/passwd

-----------以下是WHILE例子-----------

#!/bin/bash

i=1 PRE=test

while [ $i -le 10 ] do useradd $PRE$i echo "123" | passwd --stdin $PRE$i &> /dev/null let i++ done echo $i cat /etc/passwd

===================until循环语句===================== ##条件不满足循环，一旦满足则停止## 计算1~50的和值 [root@localhost ~]# vi sum1to50_until_v1.sh #!/bin/bash ##filename:sum1to50_until_v1.sh i=0;s=0 until [ $i -eq 50 ] do let "i=$i+1";let "s=$s+$i" done echo 'sum(1..50)='$s

===========================双重循环================== #!/bin/bash

H=1 while [ $H -le 10 ] do L=1 while [ $L -le $H ] do echo -n "$L" let L++ done echo"" let H++

done 最终输出： 1 12 123 1234 12345 123456 1234567 12345678 123456789 12345678910

===================shell 数组========================

Shell数组 1、获取数组长度 [root@localhost ~]# arr_number=(1 2 3 4 5); [root@localhost ~]# arr_length=${#arr_number[*]} [root@localhost ~]# echo $arr_length 5

2、读取某下标赋值 [root@localhost ~]# arr_index2=${arr_number[2]} [root@localhost ~]# echo $arr_index2 3

3、数组遍历 [root@localhost ~]# for v in ${arr_number[@]}

do echo $v done 1 2 3 4 5