linux初始化shell脚本

#!/bin/bash
# this is a init script
ping -c 1 -i 0.1 -W 1 baidu.com
a=`echo $?`
if [ ${a} == 0 ];then
    echo "network success"
else
    echo "network failer"
    exit 2
fi
systemctl stop firewalld
systemctl disable  firewalld
sed -i 's/^SELINUX=enforcing/SELINUX=disable/' /etc/selinux/config
hn=master1.localdomain
hostnamectl set-hostname ${hn}
# -----------------------------
mkdir /tmp/yum.repo.bak ;mv /etc/yum.repos.d/* /tmp/yum.repos.bak/
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
b=`echo $?`
if [ ${b} == 0 ];then
    echo "yum 替换成功"
else
    echo "yum 替换失败,将手动执行下列过程"
    exit 2
fi
yum clean all;yum makecache
yum install -y wget vim 2>&1
reboot