CentOS 6 系统优化 Shell 脚本

CentOS 已经发布了6.2版了，现在已经可以用在生产环境了，新版本的内核也能更好的利用硬件。写了一个脚本，用来初始化系统环境，现在分享出来，你可以根据自己的需要，对脚本进行相应的修改。

脚本的内容如下： 

#!/bin/bash
#author suzezhi
#this script is only for CentOS 6
#check the OS

platform=`uname -i`
if [ $platform != "x86_64" ];then
echo "this script is only for 64bit Operating System !"
exit 1
fi
echo "the platform is ok"
version=`lsb_release -r |awk '{print substr($2,1,1)}'`
if [ $version != 6 ];then
echo "this script is only for CentOS 6 !"
exit 1
fi
cat << EOF
+---------------------------------------+
|   your system is CentOS 6 x86_64      |
|      start optimizing.......          |
+---------------------------------------
EOF

#make the 163.com as the default yum repo
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
wget http://mirrors.163.com/.help/CentOS6-Base-163.repo -O /etc/yum.repos.d/CentOS-Base.repo

#add the third-party repo
#add the epel
rpm -Uvh http://download.Fedora.RedHat.com/pub/epel/6/x86_64/epel-release-6-5.noarch.rpm
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6

#add the rpmforge
rpm -Uvh http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-rpmforge-dag

#update the system and set the ntp
yum clean all
yum -y update glibc\*
yum -y update yum\* rpm\* Python\*
yum -y update
yum -y install ntp
echo "* 4 * * * /usr/sbin/ntpdate 210.72.145.44 > /dev/null 2>&1" >> /var/spool/cron/root
service crond restart

#set the file limit
echo "ulimit -SHn 102400" >> /etc/rc.local
cat >> /etc/security/limits.conf << EOF
*           soft   nofile       65535
*           hard   nofile       65535
EOF

#set the control-alt-delete to guard against the miSUSE
sed -i 's#exec /sbin/shutdown -r now#\#exec /sbin/shutdown -r now#' /etc/init/control-alt-delete.conf

#disable selinux
sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config

#set ssh
sed -i 's/^GSSAPIAuthentication yes$/GSSAPIAuthentication no/' /etc/ssh/sshd_config
sed -i 's/#UseDNS yes/UseDNS no/' /etc/ssh/sshd_config
service sshd restart

#tune kernel parametres
cat >> /etc/sysctl.conf << EOF
net.ipv4.tcp_fin_timeout = 1
net.ipv4.tcp_keepalive_time = 1200
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_synack_retries = 1
net.ipv4.tcp_syn_retries = 1
net.ipv4.tcp_tw_recycle = 1
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.netdev_max_backlog = 262144
net.core.somaxconn = 262144
net.ipv4.tcp_max_orphans = 3276800
net.ipv4.tcp_max_syn_backlog = 262144
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
EOF
/sbin/sysctl -p

#define the backspace button can erase the last character typed
echo 'stty erase ^H' >> /etc/profile
echo "syntax on" >> /root/.vimrc

#stop some crontab
mkdir /etc/cron.daily.bak
mv /etc/cron.daily/makewhatis.cron /etc/cron.daily.bak
mv /etc/cron.daily/mlocate.cron /etc/cron.daily.bak
chkconfig bluetooth off
chkconfig cups off
chkconfig ip6tables off
#disable the ipv6
cat > /etc/modprobe.d/ipv6.conf << EOFI
alias net-pf-10 off
options ipv6 disable=1
EOFI
echo "NETWORKING_IPV6=off" >> /etc/sysconfig/network
cat << EOF
+-------------------------------------------------+
|               optimizer is done                 |
|   it's recommond to restart this server !       |
+-------------------------------------------------+
EOF

对脚本的内容做一下说明：

1. 先对系统进行判断，如果是Cent OS 64位，就继续运行。
2. 先将系统的安装源设置为网易的（网易的安装源算是国内比较稳定的）
3. 安装epel的源和rpmforge的源，利用第三方的源来让yum安装起来更方便
4. 更新软件
5. 设置为每天凌晨四点进行时间同步（跟国家授时中心的服务器进行时间同步）
6. 将系统同时打开的文件个数增大
7. 将ctrl ALT delete键进行屏蔽，防止误操作的时候服务器重启
8. 关闭SELinux
9. 禁用GSSAPI来认证，也禁用DNS反向解析，加快SSH登陆速度
10. 优化一些内核参数
11. 调整删除字符的按键为backspace（某些系统默认是delete）
12. 打开vim的语法高亮
13. 取消生成whatis数据库和locate数据库
14. 关闭没用的服务
15. 关闭IPv6