MySQL forgets root password cracking root password cracking all user passwords, shell script

#!/bin/bash
# mysql  Crack reset root password 
read -p "
Hello, welcome to continuous integration eisc.cn mysql  Crack both remote and localhost Database password 
 Please enter a user name ：" setuser
read -p " Please customize your password ：" setpasswd
mycnf="/etc/my.cnf"
NR=`cat -n $mycnf | grep "\[mysqld\]" | awk -F" " '{print $1}'` ; echo $NR
                  #  find  [mysqld]  The line of the tag 
sed -i "/skip-grant-tables/d" $mycnf
                  #  Delete this root Password free login configuration , To add 
sed -i "$NR a skip-grant-tables" $mycnf ; systemctl restart mysqld mariadb
                  #  stay mysqld  Add password free login configuration information under the label 
                  #  Restart the database 
echo " The information you entered is ：$setuser $setpasswd"
mysqlversion=$(mysql -uroot -peisc.cn -e "select version();" | awk -F"." 'NR==2{print $1}') ; echo "mysql edition ：$mysqlversion";
if [ $mysqlversion -gt 7 ];then
      echo " The current database version is greater than 7"
      mysql -e "use mysql;select user,authentication_string from user; set global read_only=0;set global read_only=1; set global validate_password.policy=0 ; set global validate_password.length=6;flush privileges;alter user '$setuser'@'localhost' identified by '$setpasswd';alter user '$setuser'@'%' identified by '$setpasswd';"
   else
      mysql -e "use mysql;select user,authentication_string from user; set global read_only=0;set global read_only=1; use mysql;select user,authentication_string from user; set global read_only=0;set global read_only=1; UPDATE user SET password=password('$setpasswd') WHERE user='$setuser';"
      echo " lower than 7 Version cracking of "
fi

                  #  Log in to the database to modify root The password for ：eisc.cn
                  #  a key ：set global read_only=0;set global read_only=1; flush privileges;set global validate_password.policy=0 ; set global validate_password.length=6;
                  #  Turn off the read-only property of the new master library , Read write properties , The length of the password is 6
sed -i "/skip-grant-tables/d" $mycnf; systemctl restart mysqld mariadb
                  #  Delete the previous configuration , Restart the data 

# wget eisc.cn/file/shell/mysql-passwd.sh ; sh mysql-passwd.sh