关于旧版CentOS5.0以下无法执行yum install的问题

转载地址：http://blog.chinaunix.net/uid-20731487-id-3504282.html

由于种种原因，比如需要一直延用过去构筑的系统，或者是为了模拟旧版RedHat Enterprise版（RedHat的收费版，CentOS可以说是它的山寨版）等等，会有需要继续使用旧版的CentOS的情况。

但是由于CentOS的各个服务镜像几乎已经不支持旧版系统的升级，升级yum的时候会遇到以下问题。

# yum update
Setting up Update Process
Setting up repositories
not using ftp,http[s],or file for repos,skipping - 4 is not a valid release or hasnt been released yet
Cannot find a valid baseurl for repo: update
Error: Cannot find a valid baseurl for repo: update

提示已经找不到提供升级的支持了。但如果又非要继续使用旧版CenOS呢？我们从这里得到了启示。http://mirror.centos.org/centos/4.9/readme 
This directory (and version of CentOS) is depreciated.  

CentOS-4 is now past EOL

You can get the last released version of centos 4.9 here:

http://vault.centos.org/4.9/

对，http://vault.centos.org/还提供旧版的升级，所以我们必须修改配置文件（/etc/yum.repos.d/CentOS-Base.rpeo）来定向到这个镜像站点。方法如下

1. --- /etc/yum.repos.d/CentOS-Base.repo.orig
2. +++ /etc/yum.repos.d/CentOS-Base.repo
3. @@ -13,8 +13,9 @@
4. 
   
5. [base]
6. name=CentOS-$releasever - Base
7. -mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
8. +#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
9. #baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
10. +baseurl=http://vault.centos.org/4.9/os/$basearch/
11. gpgcheck=1
12. gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
13. priority=1
14. @@ -23,8 +24,9 @@
15. #released updates
16. [update]
17. name=CentOS-$releasever - Updates
18. -mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
19. +#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
20. #baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
21. +baseurl=http://vault.centos.org/4.9/updates/$basearch/
22. gpgcheck=1
23. gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
24. priority=1
25. @@ -33,8 +35,9 @@
26. #packages used/produced in the build but not released
27. [addons]
28. name=CentOS-$releasever - Addons
29. -mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons
30. +#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons
31. #baseurl=http://mirror.centos.org/centos/$releasever/addons/$basearch/
32. +baseurl=http://vault.centos.org/4.9/addons/$basearch/
33. gpgcheck=1
34. gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
35. priority=1
36. @@ -43,8 +46,9 @@
37. #additional packages that may be useful
38. [extras]
39. name=CentOS-$releasever - Extras
40. -mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
41. +#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
42. #baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
43. +baseurl=http://vault.centos.org/4.9/extras/$basearch/
44. gpgcheck=1
45. gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
46. priority=1
47. @@ -53,8 +57,9 @@
48. #additional packages that extend functionality of existing packages
49. [centosplus]
50. name=CentOS-$releasever - Plus
51. -mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
52. +#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
53. #baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
54. +baseurl=http://vault.centos.org/4.9/centosplus/$basearch/
55. gpgcheck=1
56. enabled=0
57. gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
58. @@ -64,8 +69,9 @@
59. #contrib - packages by Centos Users
60. [contrib]
61. name=CentOS-$releasever - Contrib
62. -mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
63. +#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
64. #baseurl=http://mirror.centos.org/centos/$releasever/contrib/$basearch/
65. +baseurl=http://vault.centos.org/4.9/contrib/$basearch/
66. gpgcheck=1
67. enabled=0
68. gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4

这样一来我们可以正常使用yum update了。

# yum update
Setting up Update Process
Setting up repositories
update                    100% |=========================|  951 B    00:00     
base                      100% |=========================| 1.1 kB    00:00     
addons                    100% |=========================|  951 B    00:00     
extras                    100% |=========================| 1.1 kB    00:00     
Reading repository metadata in from local files
primary.xml.gz            100% |=========================| 843 kB    00:01     
sqlite cache needs updating,reading in metadata
update    : ################################################## 1920/1920
No Packages marked for Update/Obsoletion

CentOS2，3的情况还没有确认过，理论上都行得通。不过嘛，如果没有特殊情况还是升级你的CentOS吧