1，判断网卡配置文件名称为eth*或者是em* ，如dell服务器网卡CentOS5为eth*，而CentOS6为em*。
2，存在几个网卡就复制几个原网卡配置文件做为桥配置文件，n的设置的数量是
3，如果超过4网卡则设置更高值，原配置文件是DHCP的改为static，用.*匹配行是存在CentOS5和6参数有引号的问题。
4， 生成虚拟机桥借口br*并一一对应，如br0对应eth0，br1对应eth1等等，并重启网络。
#! /bin/sh
mypath="/etc/sysconfig/network-scripts"
for((n=0;n<=4;n++))
do
if [ -f "$mypath/ifcfg-eth$n" ]
then
sed -i "s/^ONBOOT.*/ONBOOT=yes/" $mypath/ifcfg-eth$n
sed -i "s/^BOOTPROTO.*/BOOTPROTO=static/" $mypath/ifcfg-eth$n
cp -a $mypath/ifcfg-eth$n $mypath/ifcfg-br$n
sed -i "/^HWADDR.*/d" $mypath/ifcfg-br$n
sed -i "s/^DEVICE.*/DEVICE=br"$n"/" $mypath/ifcfg-br$n
sed -i "s/^TYPE.*/TYPE=Bridge/" $mypath/ifcfg-br$n
echo "BRIDGE=br$n">>$mypath/ifcfg-eth$n
echo "The device br$n<---->eth$n is add success !"
else
echo "The device eth$n not exist!"
fi
if [ -f "$mypath/ifcfg-em$n" ]
then
sed -i "s/^ONBOOT.*/ONBOOT=yes/" $mypath/ifcfg-em$n
sed -i "s/^BOOTPROTO.*/BOOTPROTO=static/" $mypath/ifcfg-em$n
cp -a $mypath/ifcfg-em$n $mypath/ifcfg-br$n
sed -i "/^HWADDR.*/d" $mypath/ifcfg-br$n
sed -i "s/^DEVICE.*/DEVICE=br"$n"/" $mypath/ifcfg-br$n
sed -i "s/^TYPE.*/TYPE=Bridge/" $mypath/ifcfg-br$n
echo "BRIDGE=br$n">>$mypath/ifcfg-em$n
echo "The device br$n<---->em$n is add success !"
else
echo "The device em$n not exist!"
fi
done
/etc/init.d/network restart