下面陆零云服务器网络为大家演示一下CentOS6.4升级到7.0的详细操作步骤：

　　第一步：

　　1]配置软件源

　　# vim /etc/yum.repos.d/upgrade.repo

　　[upgrade]

　　name=upgrade

　　baseurl=

　　enable=1

　　gpgcheck=0

　　[2]安装软件工具

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

　　[3]升级前检查潜在问题

　　# preupg

　　Preupg tool doesnt do the actual upgrade.

　　Please ensure you have backed up your system and/or data in the event of a failed upgrade

　　that would require a full re-install of the system from installation media.Do you want to continue? y/n

　　y

　　Gathering logs used by preupgrade assistant:

　　All installed packages : 01/10 ...finished (time 00:00s)

　　All changed files : 02/10 ...finished (time 00:40s)

　　Changed config files : 03/10 ...finished (time 00:00s)

　　All users : 04/10 ...finished (time 00:00s)

　　All groups : 05/10 ...finished (time 00:00s)

　　Service statuses : 06/10 ...finished (time 00:00s)

　　All installed files : 07/10 ...finished (time 00:01s)

　　All local files : 08/10 ...finished (time 00:03s)

　　All executable files : 09/10 ...finished (time 00:00s)

　　RedHat signed packages : 10/10 ...finished (time 00:00s)

　　Assessment of the system, running checks / SCE scripts:

　　001/100 ...done (Configuration Files to Review)

　　002/100 ...done (File Lists for Manual Migration)

　　003/100 ...done (Bacula Backup Software)

　　004/100 ...done (MySQL configuration)

　　005/100 ...done (Migration of the MySQL data stack)

　　006/100 ...done (General changes in default MySQL implementation)

　　007/100 ...done (PostgreSQL upgrade content)

　　Assessment finished (time 00:00s)

　　Result table with checks and their results for main contents:

　　------------------------------------------------------------------------------------------

　　System kickstart notapplicable

　　YUM notapplicable

　　Check for usage of dangerous range of UID/GIDs notapplicable

　　Incorrect usage of reserved UID/GIDs notapplicable

　　NIS ypbind config files back-up notapplicable

　　NIS Makefile back-up notapplicable

　　NIS server maps check notapplicable

　　NIS server MAXUID and MAXGID limits check notapplicable

　　NIS server config file back-up notapplicable

　　------------------------------------------------------------------------------------------

　　Tarball with results is stored here /root/preupgrade-results/preupg_results-4.tar.gz .

　　The latest assessment is stored in directory /root/preupgrade .

　　Upload results to UI by command:

　　e.g. preupg -u

　　[4]开始升级

　　# rpm --import

　　正常的运行以上命令可以升级完成；

　　# redhat-upgrade-tool --network 7.0 --instrepo

　　这强制的就显得有点不友好了，生产环境慎用；

　　更新到这一步：

　　setting up repos...

　　.treeinfo 1.1 kB 00:00

　　getting boot images...

　　vmlinuz-redhat-upgrade-tool 4.7 MB 01:38

　　initramfs-redhat-upgrade-tool.img 32 MB 14:45

　　setting up update...

　　finding updates 100% [=====================================================================================================]

　　(1/272): acl-2.2.51-12.el7.x86_64.rpm 81 kB 00:00

　　(2/272): attr-2.4.46-12.el7.x86_64.rpm 66 kB 00:00

　　(3/272): audit-2.3.3-4.el7.x86_64.rpm 223 kB 00:01

　　(4/272): audit-libs-2.3.3-4.el7.x86_64.rpm 77 kB 00:00

　　(5/272): authconfig-6.2.8-8.el7.x86_64.rpm 399 kB 00:08

　　(6/272): basesystem-10.0-7.el7.centos.noarch.rpm 5.0 kB 00:00

　　(7/272): bash-4.2.45-5.el7.x86_64.rpm 1.0 MB 00:17

　　(270/272): yum-plugin-fastestmirror-1.1.31-24.el7.noarch.rpm 28 kB 00:03

　　(271/272): zlib-1.2.7-13.el7.x86_64.rpm 89 kB 00:06

　　(272/272): zlib-devel-1.2.7-13.el7.x86_64.rpm 49 kB 00:01

　　setting up system for upgrade

　　Finished. Reboot to start upgrade.

　　# reboot

　　[5]升级完成:

　　# cat /etc/redhat-release

　　CentOS Linux release 7.0.1406 (Core)

　　
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