Shell 脚本实践

#!/bin/bash
read -p "input you choice（y/n）:" choice
[ "$choice" == "y" ] || [ "$choice" == "Y" ] && echo "OK,continue" && exit 0
[ "$choice" == "n" ] || [ "$choice" == "N" ] && echo "Oh,interrupt!" && exit 0
echo "I don‘t know what is your choice" && exit 0

#! /bin/sh

echo "Is it morning? Please answer yes or no."
read YES_OR_NO
if [ "$YES_OR_NO" = "yes" ]; then
  echo "Good morning!"
elif [ "$YES_OR_NO" = "no" ]; then
  echo "Good afternoon!"
else
  echo "Sorry, $YES_OR_NO not recognized. Enter yes or no."
  exit 1
fi
exit 0

和C语言类似。比如一个验证密码的脚本：

#! /bin/sh
echo "Enter password:"
read TRY
while [ "$TRY" != "secret" ]; do
  echo "Sorry, try again"
  read TRY
done
下面的例子通过算术运算控制循环的次数：

#! /bin/sh

COUNTER=1
while [ "$COUNTER" -lt 10 ]; do
  echo "Here we go again"
  COUNTER=$(($COUNTER+1))
done

#!/bin/bash
while :                                   ：表示真，一直循环
do                                        要循环执行的命令
        echo -n "enter any number [1-5]:" 输入序号1-5
        read nu                            设置read的变量
        case $nu in                        进行选择，输入的要是1-5的数字
        1|2|3|4|5)
                echo "enter anumber 1 and 5" 就循环这一行，让你不停的输入1-5
                ;;
        *)                                   如果输入的不是1-5的数字
                echo -n "wrong number, continue (y/n?:)"   询问你是否继续
                read con                     设置read的变量
                case $con in                 进行选择，看是不是y|yes|Y|YES这几个
                y|yes|Y|YES)
                        continue              如果是，那么就跳过，让你重新输入，如果不是
                        ;;
                *)                             那么就执行这个break退出循环
                        break
                        ;;
                esac
        esac
done