作为运维人员，经常会初始化系统，系统在安装过程中基本都会选择最小化安装，这样安装好的系统里会缺少很多环境。
下面分享一个系统安装后的初始化脚本：
#!/bin/bash
#系统时最小化安装的，这里要安装系统的软件库
yum groupinstall -y "development tools"
#创建目录
[ ! -d /server/tools ] && mkdir -p /server/tools
[ ! -d /application ] && mkdir -p /application
[ ! -d /data ] && mkdir -p /data
[ ! -d /app/logs ] && mkdir -p /app/logs
[ ! -d /server/backup ] && mkdir -p /server/backup
[ ! -d /delete ] && mkdir -p /delete
#创建普通用户并设置密码
#for USERNAME in gladiator cgt zm
#do
# id $USERNAME >/dev/null 2>&1 && echo "user $USERNAME exists,only change password" || useradd $USERNAME
# echo "123456"|passwd $USERNAME --stdin
# id $USERNAME && action "add user" /bin/true || action "add user" /bin/false
#设置sudo权限管理，给管理员权限
#*******修改任何配置文件前先备份********
# /bin/cp /etc/sudoers /etc/sudoers.bak
# echo "$USERNAME ALL=(ALL) ALL" >> /etc/sudoers
# [ `grep $USERNAME /etc/sudoers|wc -l` -ne 0 ] && action "sudo set" /bin/true || action "sudo set" /bin/false
#done
#每周六凌晨1点0分更新服务器系统时间
echo "############### auto update time ###############" >> /var/spool/cron/root
echo "00 01 * * * /usr/sbin/ntpdate time.nist.gov >/dev/null 2>&1" >> /var/spool/cron/root
[ `grep ntpdate /var/spool/cron/root |wc -l` -ne 0 ] && action "uptime set" /bin/true || action "uptime set" /bin/false
#配置yum源
wget -P /etc/yum.repos.d/ http://mirrors.163.com/.help/CentOS6-Base-163.repo #下载配置文件
/bin/mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
/bin/cp /etc/yum.repos.d/CentOS6-Base-163.repo /etc/yum.repos.d/CentOS-Base.repo
[ `grep 163.com /etc/yum.repos.d/CentOS-Base.repo | wc -l` -ne 0 ] && action "yum set" /bin/true || action "yum set" /bin/false
#关闭SELINUX及iptables
/bin/cp /etc/selinux/config /etc/selinux/config.bak
sed -i ‘s/SELINUX=enforcing/SELINUX=disabled/‘ /etc/selinux/config 2>&1
/etc/init.d/iptables stop >/dev/null
chkconfig iptables off >/dev/null
[ `chkconfig --list |grep iptables|grep 3:on|wc -l` -eq 0 -a `grep "SELINUX=enforcing" /etc/selinux/config|wc -l` -eq 0 ] && action "iptables and selinux close" /bin/true || action "iptables and selinux close" /bin/false
#调整文件描述符数量
/bin/cp /etc/security/limits.conf /etc/security/limits.conf.bak
echo ‘* - nofile 65535‘>>/etc/security/limits.conf
[ `tail -1 /etc/security/limits.conf|grep 65535|wc -l` -eq 1 ] && action "limit set" /bin/true || action "limit set" /bin/false
#更改字符集
#/bin/cp /etc/sysconfig/i18n /etc/sysconfig/i18n.bak
#echo ‘LANG="en_US.UTF-8"‘ >/etc/sysconfig/i18n
#定时清理/var/spool/clientmqueue/目录下的垃圾文件，防止inodes节点被占满
##创建脚本目录
[ ! -d /server/scripts ] && mkdir -p /server/scripts
if [ `rpm -qa sendmail |wc -l` -ne 0 ];then
##创建查找删除脚本
echo >/server/scripts/del.sh<<EOF
\#!/bin/bash
find /var/spool/clientmqueue/ -type f|xargs rm -f >/dev/null 2>&1
EOF
##添加到定时任务，每周一凌晨0点0分执行
echo ‘################ clean /var/spool/clientmqueue/ ################‘ >>/var/spool/cron/root
echo ‘00 00 * * 1 /bin/sh /server/scripts/del.sh >/dev/null 2>&1‘ >>/var/spool/cron/root
[ "$?" -eq 0 ] && action "clean /var/spool/clientmqueue/ set" /bin/true || action "clean /var/spool/clientmqueue/ set" /bin/false
else
action "service sendmail is not installed,do not need set" /bin/false
fi
#精简开机自启动服务（只启动crond,sshd,network,syslog)
##筛选出所有在运行级别3自启动的服务并关闭自启动
for cgt in `chkconfig --list | grep 3:on | awk ‘{print $1}‘`;do chkconfig --level 3 $cgt off;done
##仅设置crond,sshd,network,syslog自启动
for cgt in {crond,sshd,network,rsyslog};do chkconfig --level 3 $cgt on;done
flag=0
[ `chkconfig --list|grep 3:on|wc -l` -eq 4 ] && action "auto_start services set" /bin/true || action "auto_start services set" /bin/false
#内核参数优化
[ -f /etc/sysctl.conf.bak ] && /bin/cp /etc/sysctl.conf.bak /etc/sysctl.conf.bak.$(date +%F-%H%M%S) ||/bin/cp /etc/sysctl.conf /etc/sysctl.conf.bak
cat >> /etc/sysctl.conf <<EOF
net.ipv4.tcp_fin_timeout = 2
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_keepalive_time = 600
net.ipv4.ip_local_port_range = 4000 65000
net.ipv4.tcp_max_syn_backlog = 16384
net.ipv4.tcp_max_tw_buckets = 36000
net.ipv4.route.gc_timeout = 100
net.ipv4.tcp_syn_retries = 1
net.ipv4.tcp_synack_retries = 1
net.core.somaxconn = 16384
net.core.netdev_max_backlog = 16384
net.ipv4.tcp_max_orphans = 16384
#以下参数是对iptables防火墙的优化，防火墙不开会提示，可以忽略不理。
#net.ipv4.ip_conntrack_max = 25000000
#net.ipv4.netfilter.ip_conntrack_max=25000000
#net.ipv4.netfilter.ip_conntrack_tcp_timeout_established=180
#net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait=120
#net.ipv4.netfilter.ip_conntrack_tcp_timeout_close_wait=60
#net.ipv4.netfilter.ip_conntrack_tcp_timeout_fin_wait=120
#net.netfilter.nf_conntrack_max = 25000000
#net.netfilter.nf_conntrack_tcp_timeout_established = 180
#net.netfilter.nf_conntrack_tcp_timeout_time_wait = 120
#net.netfilter.nf_conntrack_tcp_timeout_close_wait = 60
#net.netfilter.nf_conntrack_tcp_timeout_fin_wait = 120‘
EOF
sysctl -p >/dev/null 2>&1
[ `grep "net.ipv4.tcp_max_orphans = 16384" /etc/sysctl.conf|wc -l` -ne 0 ] && action "kernel set" /bin/true || action "kernel set" /bin/false
#更改默认的ssh服务端口，禁止root用户远程连接，禁止空密码连接
/bin/cp /etc/ssh/sshd_config /etc/ssh/sshd_config.bak
#sed -i ‘s/\#Port 22/Port 52113/‘ /etc/ssh/sshd_config
sed -i ‘s/\#PermitRootLogin yes/PermitRootLogin no/‘ /etc/ssh/sshd_config
sed -i ‘s/\#PermitEmptyPasswords no/PermitEmptyPasswords no/‘ /etc/ssh/sshd_config
sed -i ‘s/\#UseDNS yes/UseDNS no/‘ /etc/ssh/sshd_config
#[ `grep "Port 52113" /etc/ssh/sshd_config |wc -l` -ne 0 -a `grep "PermitRootLogin no" /etc/ssh/sshd_config|wc -l` -ne 0 -a `grep "PermitEmptyPasswords no" /etc/ssh/sshd_config|wc -l` -ne 0 -a `grep "UseDNS no" /etc/ssh/sshd_config|wc -l` -ne 0 ] &&action "ssh set" /bin/true || action "ssh set" /bin/false
[ `grep "PermitRootLogin no" /etc/ssh/sshd_config|wc -l` -ne 0 -a `grep "PermitEmptyPasswords no" /etc/ssh/sshd_config|wc -l` -ne 0 -a `grep "UseDNS no" /etc/ssh/sshd_config|wc -l` -ne 0 ] &&action "ssh set" /bin/true || action "ssh set" /bin/false
#锁定关键系统文件
#chattr +i /etc/passwd
#chattr +i /etc/shadow
#chattr +i /etc/group
#chattr +i /etc/gshadow
#chattr +i /etc/inittab
#清空/etc/issue，去除系统及内核版本登陆前的屏幕显示
/bin/cp /etc/issue /etc/issue.bak
>/etc/issue
[ `cat /etc/issue|wc -l` -eq 0 ] && action "/etc/issue set" /bin/true || action "/etc/issue set" /bin/false