shell脚本简单例子

eg：

Expect：

1.用环境变量RANDOM随机生成一个100以内的随机数

2.read读取当前输入

3.当前输入对比随机生成的数

4.当两个数相等时跳出苏循环，并计数（比较n次结果才相等）

 #!/bin/bash
 i=
 num=$(expr $RANDOM % )
 echo $num
 while true
 do
         let i++
         read -p "Please input number(1-100):" digit
         if [ $digit -eq $num ]; then
                 echo $digit
                 echo "一共$i 次!!"
                 break
         elif [ $digit -lt $num ]; then
                 echo "The number is less!"
         elif [ $digit -gt $num -o $digit -gt  ]; then
                 echo "The number is bigger"
         #elif [ $digit -gt 100 ]; then
         #       echo "not in the range!! Please reinput."
         else
                 continue
         fi
 done

eg:

复习简单实例 ，    简单输入n次要取得值，最后打印出获得的所有值

 #!/bin/bash
 attr=()
 num=
 while true
 do
         read -p ">>input:" name
         attr[$num]=$name
         echo ${attr[$num]}
         let num++
         if [ $num -eq  ]; then
                 echo ${attr[*]}
                 exit
         fi
 done

eg：for循环

eg：continue和break的区别

　　continue结束本次循环，进行下一次循环

　　break跳过本次循环

 #!/bin/bash
 for i in `seq `
 do
         if [ $i -eq  ]; then
                 continue
         else
                 echo $i
         fi
 done

 #!/bin/bash
 int=
 while :
 do
         let int++
         if [ $int -lt  ]; then
                 echo $int
         else
                 break
         fi
 done
 ====================
 for循环的用法
 #!/bin/bash
 for ((a=;a<;a++))
 do
         echo $a
 done
 ====================
 嵌套循环
 #!/bin/bash
 for ((a=;a<;a++))
 do
         echo "outer loop: $a"
         for ((b=;b<;b++))
         do
                 if [ $b -eq  ]; then
                         continue
                 else
                         echo "inner loop: $b"
                 fi
         done
 done
 ====================

shell脚本编写添加用户，随机密码后五位

 #!/bin/bash
 for ((i=;i<;i++))
 do
         password=`openssl rand -hex  | cut -c1-`
         echo "$password"
         cat /etc/passwd|grep -qa user$i
         if [ $? -eq  ]; then
                 echo "user${i} already"
                 continue
         else
                 useradd user$i;echo $a|passwd --stdin user$i
         fi
 done