在virtualBox虚拟机中安装好CentOS5.5之后，安装增强功用起来会顺畅一点，特别是虚拟机与主机之间的交互更方便。
以root身份登录虚拟机，双击VirtualBox安装目录下的autorun.sh，运行结果如下：
1: Verifying archive integrity... All good. 2: Uncompressing VirtualBox 4.3.4 Guest Additions for Linux............
3: VirtualBox Guest Additions installer 4: Removing installed version 4.3.4 of VirtualBox Guest Additions... 5: Copying additional installer modules ... 6: Installing additional modules ... 7: Removing existing VirtualBox non-DKMS kernel modules [确定] 8: Building the VirtualBox Guest Additions kernel modules 9: The headers for the current running kernel were not found. If the following
10: module compilation fails then this could be the reason.
11: The missing package can be probably installed with 12: yum install kernel-devel-2.6.18-194.el5 13: 14: Building the main Guest Additions module [失败] 15: (Look at /var/log/vboxadd-install.log to find out what went wrong)
16: Doing non-kernel setup of the Guest Additions [确定] 17: Installing the Window System drivers 18: Installing X.Org 7.1 modules [确定] 19: Setting up the Window System to use the Guest Additions [确定] 20: The following X.Org/XFree86 configuration files were originally generated by 21: the VirtualBox Guest Additions and were not modified: 22: 23: /etc/X11/xorg.conf 24: 25: You may need to restart the hal service and the Window System (or just restart 26: the guest system) to enable the Guest Additions. 27: 28: Installing graphics libraries and desktop services componen[确定] 29: Press Return to close this window...
打开/var/log/vboxadd-install.log，得到错误信息如下：
/tmp/vbox.0/Makefile.include.header:97: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR=<directory> and run Make again。 停止。
Creating user for the Guest Additions.
Creating udev rule for the Guest Additions kernel module.
通过上面的提示可以可以知道找不到linux内核的源文件。具体的解决办法如下：
1.安装gcc，kernel，kernel-devel
gcc是linux下常进的编译器。kernel是内核，kernel-devel是用来构建与内核匹配的内核模块的开发软件包。安装方式很简单，直接用yum install gcc这样的形式安装即可。
2.重启电脑，系统从新的内核启动，之后再重新安装增强包即可。