今天找了一台P4的老服务器安装CentOS 5.5 ，系统安装完毕以后，通过YUM安装GCC出现错误
[root@localhost ~]# yum install gcc
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: centos.ustc.edu.cn
* base: centos.ustc.edu.cn
* extras: centos.ustc.edu.cn
* updates: centos.ustc.edu.cn
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package gcc.i386 0:4.1.2-48.el5 set to be updated
--> Processing Dependency: cpp = 4.1.2-48.el5 for package: gcc
--> Processing Dependency: libgomp >= 4.1.2-48.el5 for package: gcc
--> Processing Dependency: glibc-devel >= 2.2.90-12 for package: gcc
--> Running transaction check
---> Package cpp.i386 0:4.1.2-48.el5 set to be updated
---> Package glibc-devel.i386 0:2.5-49.el5_5.2 set to be updated
--> Processing Dependency: glibc = 2.5-49.el5_5.2 for package: glibc-devel
--> Processing Dependency: glibc-headers = 2.5-49.el5_5.2 for package: glibc-devel
--> Processing Dependency: glibc-headers for package: glibc-devel
---> Package libgomp.i386 0:4.4.0-6.el5 set to be updated
--> Running transaction check
--> Processing Dependency: glibc = 2.5-49 for package: nscd
---> Package glibc.i686 0:2.5-49.el5_5.2 set to be updated
--> Processing Dependency: glibc-common = 2.5-49.el5_5.2 for package: glibc
---> Package glibc-headers.i386 0:2.5-49.el5_5.2 set to be updated
--> Processing Dependency: kernel-headers >= 2.2.1 for package: glibc-headers
--> Processing Dependency: kernel-headers for package: glibc-headers
--> Running transaction check
---> Package glibc-common.i386 0:2.5-49.el5_5.2 set to be updated
---> Package kernel-headers.i386 0:2.6.18-194.3.1.el5 set to be updated
---> Package nscd.i386 0:2.5-49.el5_5.2 set to be updated
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
gcc i386 4.1.2-48.el5 base 5.2 M
Installing for dependencies:
cpp i386 4.1.2-48.el5 base 2.6 M
glibc-devel i386 2.5-49.el5_5.2 updates 2.0 M
glibc-headers i386 2.5-49.el5_5.2 updates 602 k
kernel-headers i386 2.6.18-194.3.1.el5 updates 1.0 M
libgomp i386 4.4.0-6.el5 base 70 k
Updating for dependencies:
glibc i686 2.5-49.el5_5.2 updates 5.3 M
glibc-common i386 2.5-49.el5_5.2 updates 16 M
nscd i386 2.5-49.el5_5.2 updates 165 k
Transaction Summary
================================================================================
Install 6 Package(s)
Upgrade 3 Package(s)
Total download size: 34 M
Is this ok [y/N]: y
Downloading Packages:
(1/9): l
(2/9): n
(3/9): g | 432 kB
(4/9): k | 1.0 MB
(5/9): g | 2.0 MB
(6/9): c | 2.6 MB
(7/9): g | 5.2 MB
(8/9): g | 5.3 MB
(9/9): g | 16 MB
--------
Total
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID e8562897
updates/
Importing GPG key 0xE8562897 "CentOS-5 Key (CentOS 5 Official Signing Key) <centos-5-key@centos.org>" from /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5
Is this ok [y/N]: Warning Timer ISR/0: Time went backwards: delta=-44964083 delta_cpu=-40964083 shadow=16343833542498 off=681332763 processed=16344558737755 cpu_processed=16344554737755
0: 16344554737755
Warning Timer ISR/0: Time went backwards: delta=-24292783 delta_cpu=-20292783 shadow=16343833542498 off=700981488 processed=16344558737755 cpu_processed=16344554737755
0: 16344554737755
Warning Timer ISR/0: Time went backwards: delta=-40370193 delta_cpu=-40370193 shadow=16343833542498 off=764827610 processed=16344638737755 cpu_processed=16344638737755
0: 16344638737755
Not installing key
上网查了一下是KEY没有导入， 从光盘上把 RPM-GPG-KEY-CentOS-5 文件考到服务器上，
通过命令 rpm --import RPM-GPG-KEY-CentOS-5
然后就正常了。
