ceontos6.5升级到centos7.2

1.安装yum

#添加访问互联路由
cat > /etc/resolv.conf <<EOF
nameserver 114.114.114.114
nameserver 223.5.5.5
nameserver 8.8.8.8
EOF

cat /etc/resolv.conf

cd /etc/yum.repos.d


#备份yum源
rm -rf /etc/yum.repos.d/bak && mkdir -p /etc/yum.repos.d/bak && mv /etc/yum.repos.d/* /etc/yum.repos.d/bak



cat>  /etc/yum.repos.d/upgrade.repo <<'EOF'
#############################

[base]
name=CentOS-Base(GDS)
baseurl=http://192.168.1.2/6/base
path=/
enabled=1
gpgcheck=0
 
[updates]
name=CentOS-Updates(GDS)
baseurl=http://192.168.1.2/6/updates
path=/
enabled=1
gpgcheck=0
 
[extras]
name=CentOS-Extras(GDS)
baseurl=http://192.168.1.2/6/extras
path=/
enabled=1
gpgcheck=0

#############################

EOF



yum -y install vim net-tools lrzsz unzip gcc telnet wget curl


yum clean all && yum makecache yum update -y


cd /etc/yum.repos.d


rm -rf /etc/yum.repos.d/CentOS-*

2.安装更新助手

service iptables stop 
chkconfig iptables off


wget http://192.168.1.2/6/openscap-1.0.8-1.0.1.el6.centos.x86_64.rpm
wget http://192.168.1.2/6/preupgrade-assistant-1.0.2-36.0.1.el6.centos.x86_64.rpm
wget http://192.168.1.2/6/preupgrade-assistant-contents-0.5.14-1.el6.centos.noarch.rpm
wget http://192.168.1.2/6/redhat-upgrade-tool-0.7.22-3.el6.centos.noarch.rpm



#由于centos 6.5自带的助手之一版本较高，所以需要卸载了装个更老的：
yum erase openscap -y

yum install -y pcre pcre-devel libxml2-devel libexslt libxslt  libxslt-devel pkgconfig

yum update -y


rpm -ivh *rpm


yum install redhat-upgrade-tool preupgrade-assistant-contents -y

3.运行模拟升级工具

preupg -s CentOS6_7

升级检测通过后，在线下载centos7镜像，或者通过sftp本地上传。
先导入RPM签名证书

cd /root
#rpm --import https://mirrors.ustc.edu.cn/epel/RPM-GPG-KEY-EPEL-7

wget http://192.168.1.2/6/RPM-GPG-KEY-EPEL-7

rpm --import RPM-GPG-KEY-EPEL-7

4.进行本地更新

利用下载好的镜像进行本地更新：

cd /root
wget http://192.168.1.2/6/CentOS-7-x86_64-DVD-1511.iso

centos-upgrade-tool-cli --iso=/root/CentOS-7-x86_64-DVD-1511.iso



reboot

5.升级后无法登入

选择CentOS 7内核，按e，选择光标在kernel行，再按e，在内核启动参数rhgb quite后面加 init=/bin/sh ，回车保存，按b启动

init=/bin/sh


mount -o remount,rw /sysroot

passwd root


#修复一下几个库的软链接
ln -s /usr/lib64/libsasl2.so.3.0.0 /usr/lib64/libsasl2.so.2
ln -s /usr/lib64/libpcre.so.1.2.0 /usr/lib64/libpcre.so.0


fixfiles完成后重启，还是执行权限错误。看来还是要动selinux了。在拯救模式下修改/etc/sysconfig/selinux
把
SELINUX=enforcing
改为
SELINUX=permissive

6.安装然后更新

rm -rf /etc/yum.repos.d/bak && mkdir -p /etc/yum.repos.d/bak && mv /etc/yum.repos.d/* /etc/yum.repos.d/bak

cd /etc/yum.repos.d
#下载插件
wget http://192.168.1.2/centos7/CentOS7-Base.repo


#重新安装python
yum reinstall python -y


# 设置grub2默认引导为0
grub2-set-default 0


# 重新生成grub2引导文件
grub2-mkconfig -o /boot/grub2/grub.cfg

reboot