1、批量创建用户

#!/bin/bash
read -p "请输入要创建的用户名(空格隔开):" user_list
for user in $user_list;do
  if ! id $user &> /dev/null;then
#给用户设置随机密码
    pass=`echo $RANDOM | md5sum | cut -c 1-6`
    useradd $user
    echo $pass | passwd --stdin $user
    echo "$user $pass" >> /opt/user_file
  else
    echo "$user user already exists!!!"
  fi
done

2、资源检查

#!/bin/bash
cpu_check(){
  cpu_util=`vmstat | awk 'NR==3 {print $13+$14"%"}'`
  iowait=`vmstat | awk 'NR==3 {print $16"%"}'`
  echo "---CPU使用情况---" && echo "cpu的使用率和等待磁盘IO响应使用率分别是: $cpu_util $iowait"
}

memory_check(){
  memory_total=`free -h | awk 'NR==2 {print $2}'`
  memory_used=`free -h | awk 'NR==2 {print $3}'`
  memory_available=`free -h | awk 'NR==2 {print $NF}'`
  echo "---内存使用情况---" && echo "内存总大小:$memory_total,已使用:$memory_used,剩余:$memory_available"
}

disk_check(){
  Fs=`df -h | awk '/^\/dev/ {print $1}'`
  echo "---磁盘使用情况---"
  for i in $Fs;do
    fs=`df -h | awk -v x=$i '$1==x {print $1}'`
    mounted=`df -h | awk -v x=$i '$1==x {print $NF}'`
    size=`df -h | awk -v x=$i '$1==x {print $2}'`
    used=`df -h | awk -v x=$i '$1==x {print $3}'`
    used_percent=`df -h | awk -v x=$i '$1==x {print $5}'`
    echo "Filesystem $fs挂载点为: $mounted,总大小: $size,已使用: $used,使用率: $used_percent"
  done
}

tcp_status(){
  tcp_status=`ss -antp | awk 'NR!=1 {x[$1]++}END{for(i in x)print i":"x[i]}'`
  echo "---TCP连接状态---" && echo "$tcp_status"
}

cpu_check
memory_check
disk_check
tcp_status

3、系统配置初始化

#!/bin/bash
#减少swap使用,设置权重
echo "0" > /proc/sys/vm/swappiness

# 安装相关工具、软件包，dos2unix可以将Windows文件格式转换linux/unix文件
yum -y install vim make wget gcc gcc-c++ net-tools zip sysstat iostat iftop iotp lrzsz dos2unix

# 设置时区并同步网络时间
rm -f /etc/localtime
## 同步上海时区
ln -s /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
yum -y install chrony &> /dev/null
sed -ri 's/.*pool.ntp.org.*/#&/' /etc/chrony.conf
sed -ri '/.*centos.pool.ntp.org.*/a\server ntp1.aliyun.com iburst' /etc/chrony.conf
systemctl start chronyd && systemctl enable chronyd

# 禁用Selinux
setenforce 0
sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config

# 关闭防火墙
if uname -a | grep el[7-8] &> /dev/null;then
  systemctl stop firewalld && systemctl disable firewalld
elif uname -a | grep el6 &> /dev/null;then
  service iptables stop  && chkconfig iptables off
fi

# history显示操作时间和操作用户
if ! grep HISTTIMEFORMAT ~/.bashrc;then
  echo 'export HISTTIMEFORMAT="%F %T `whoami`" ' >> ~/.bashrc
  source ~/.bashrc
fi

# SSH超时时间设置,超时自动断开,且设置了用户不能随意更改，更改需要注释readonly TMOUT行
if ! (grep "export TMOUT" /etc/profile) &> /dev/null && ! (grep "set autologout" /etc/csh.cshrc) &> /dev/null;then
  echo "export TMOUT=300" >> /etc/profile && echo "readonly TMOUT" >> /etc/profile
  source /etc/profile
  readonly TMOUT
else
  echo "已配置过超时时间"
fi

# 禁止root远程登录
sed -ri '0,/PermitRootLogin.*/s//PermitRootLogin no/' /etc/ssh/sshd_config
if grep [7-8] /etc/redhat-release;then
  systemctl restart sshd
elif grep 6 /etc/redhat-release;then
  /etc/init.d/sshd restart
fi

# 禁止定时任务发送邮件，定时任务执行后会在/var/mail下面自动生成文件，如果不设置，会占用磁盘空间
sed -i 's/^MAILTO=root/MAILTO=""/' /etc/crontab

# 设置最大打开文件数
if ! grep "* soft nofile 65535" /etc/security/limits.conf &>/dev/null; then
cat >> /etc/security/limits.conf << EOF
  * soft nofile 65535
  * hard nofile 65535
EOF
fi

# 系统内核优化
cat >> /etc/sysctl.conf << EOF
  net.ipv4.tcp_syncookies = 1
  net.ipv4.tcp_max_tw_buckets = 20480
  net.ipv4.tcp_max_syn_backlog = 20480
  net.core.netdev_max_backlog = 262144
  net.ipv4.tcp_fin_timeout = 20
EOF

4、CPU、memory 消耗 top10

#!/bin/bash
#按照CPU使用率排序，会显示pid,cpu,memory,进程
echo "------------cpu top 10-------------------"
ps -eo pid,pcpu,pmem,args --sort=-pcpu | head

#按照内存使用率排序，会显示pid,cpu,memory,进程
echo "------------memory top 10-------------------"
ps -eo pid,pcpu,pmem,args --sort=-pmem | head 

5、网卡流量监控

#!/bin/bash
#执行脚本时请指定要监控的网卡名称
eth=$1
echo "---------网卡进出流量监控中---------"
echo "--IN----------OUT--"
while true;do
  #第一次取网卡进出的流量
  IN_1=`cat /proc/net/dev | grep $eth | awk '{print $2}'`
  OUT_1=`cat /proc/net/dev | grep $eth | awk '{print $10}'`
  sleep 1
  #第二次取网卡进出的流量
  IN_2=`cat /proc/net/dev | grep $eth | awk '{print $2}'`
  OUT_2=`cat /proc/net/dev | grep $eth | awk '{print $10}'`
  #第二次减第一次网卡的差，不断循环，单位为 kb/s
  IN=`printf "%.2f%s" "$((($IN_2-$IN_1)/1024))" "KB/s"`
  OUT=`printf "%.2f%s" "$((($OUT_2-$OUT_1)/1024))" "KB/s"`
  echo "$IN   $OUT"
  sleep 1
done