指令如下：

dnf --disablerepo '*' --enablerepo extras swap centos-linux-repos centos-stream-repos
dnf distro-sync

cat /etc/centos-release
# CentOS Stream release 8

yum -y install holland-mysqldump.noarch
# mysqldump -h[地址] -P[端口号]  -u[用户名]  -p[密码]  数据库名/--all-databases| gzip > db_dump.sql.gz