Shell脚本：一键优化系统脚本

#!/bin/bash
export PATH=$PATH:/bin:/sbin:/usr/sbin
if [ "$UID" != "0" ];then
  echo "Please run this script by root."
  exit 1
fi
function mod_yum(){
  if [ -e /etc/yum.repos.d/CentOS-Base.repo ]
    then
      mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak && \
      wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-6.repo
  fi
}
function close_selinux(){
  sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config
  setenforce 0 &>/dev/null
}
function close_iptables(){
  /etc/init.d/iptables stop
  chkconfig iptables off
}
function least_service(){
  chkconfig|awk '{print "chkconfig",$1,"off"}'|bash
  chkconfig|egrep "crond|sshd|network|rsyslog|sysstat"|awk '{print "chkconfig",$1,"on"}'|bash
}
function update_linux(){
  if [ `rpm -qa lrzse nmap tree dos2unix nc|wc -l` -le 3 ]
    then
      yum install -y lrzse nmap tree dos2unix nc
  fi
}
main(){
  mod_yum
  close_selinux
  close_iptables
  least_service
  update_linux
}
main