5）测试更新源修改的效果：
#yum list
运行结果为：
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Installed Packages
Deployment_Guide-zh-CN.noarch 5.2-11.el5.CentOS installed
…
zsh-html.i386 4.2.6-3.el5 local
而如果可以连通互联网，yum list的结果如下：
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirror.bit.edu.cn
* extras: mirror.bit.edu.cn
* updates: mirror.bit.edu.cn
Installed Packages
Deployment_Guide-zh-CN.noarch 5.2-11.el5.centos installed
…
zsh-html.i386 4.2.6-6.el5 base
6）通过yum install安装gdb:
#yum -y install gdb
运行结果为：
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package gdb.i386 0:6.8-37.el5 set to be updated
--> Finished Dependency Resolution
Dependencies Resolved
…（省略）
Install 1 Package(s)
Update 0 Package(s)
Remove 0 Package(s)
Total download size: 3.4 M
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
Installing: gdb 1/1
Installed:gdb.i386 0:6.8-37.el5
Complete!
7）以上说明安装成功了，运行gdb：
# gdb
运行结果为：
GNU gdb Fedora (6.8-37.el5)
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i386-RedHat-linux-gnu".
(gdb)
到此，gdb需求完成。