一、read命令
1、概念：
默认接受键盘的输入，回车符代表输入结束
2、read命令选项
-p：打印信息
-t：限定时间
-s：不回显
-n：输入字符个数
3、举例说明
（1）模拟登录
[root@localhost test20210724]# vi read_command_study.sh
#!usr/bin/bash
clear
echo -n -e "Login: "
read acc
echo -n -e "Password: "
read pw
echo "account:$acc password:$pw"
查看运行结果：
[root@localhost test20210724]# sh read_command_study.sh
Login: root
Password: 123
account:root password:123
（2）优化：read -s #不显示密码
[root@localhost test20210724]# vi read_command_study.sh
#!usr/bin/bash
clear
echo -n -e "Login: "
read acc
echo -n -e "Password: "
read -s pw
echo
echo "account:$acc password:$pw"
查看运行结果：
[root@localhost test20210724]# sh read_command_study.sh
Login: root
Password:
account:root password:123
（3）优化：read -t5 #增加5秒超时，5秒不输入退出
[root@localhost test20210724]# vi read_command_study.sh
#!usr/bin/bash
clear
echo -n -e "Login: "
read acc
echo -n -e "Password: "
read -s -t5 pw
echo
echo "account:$acc password:$pw"
查看运行结果：
[root@localhost test20210724]# sh read_command_study.sh
Login: root
Password:
account:root password:
（4）优化：read -n6 #密码只识别6位，超过6位自动输出完成
[root@localhost test20210724]# vi read_command_study.sh
#!usr/bin/bash
clear
echo -n -e "Login: "
read acc
echo -n -e "Password: "
read -s -t5 -n6 pw
echo
echo "account:$acc password:$pw"
查看运行结果：
[root@localhost test20210724]# sh read_command_study.sh
Login: root
Password:
account:root password:123456
（5）优化：read -p "Login: " acc #read并且打印输出
[root@localhost test20210724]# vi read_command_study.sh
#!usr/bin/bash
clear
read -p "Login: " acc
read -s -t5 -n6 -p "Password: " pw
echo
echo "account:$acc password:$pw"
查看运行结果：
[root@localhost test20210724]# sh read_command_study.sh
Login: root
Password:
account:root password:123