shell_script练习题

1. 获取随机生成的8位字符串：
    # echo $RANDOM | md5sum | cut -c 1-8
    # openssl rand -base64 4
    # cat /proc/sys/kernel/random/uuid | cut -c 1-8

2. 获取随机的8位数字：
    # echo $RANDOM |cksum |cut -c 1-8
    # openssl rand -base64 4 | cut -c 1-8
    # date +%N |cut -c 1-8

3. 检查软件包是否安装：
    #!/usr/bin/env bash
    if rpm -qa sysstat &>/dev/null; then
        echo "sysstat is already installed."
    else
        echo "sysstat is not installed!"
    fi

4. 监控系统中的重要地方：
cpu：
# cat cpu_vmstat.sh
#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=`ifconfig | awk -F' ' 'NR==2{print $2}'`
MAIL="liuchao07a@163.com"
if ! which vmstat &>/dev/null; then
    echo "vmstat command no found, Please install procps package."
    exit 1
fi
US=$(vmstat |awk 'NR==3{print $13}')
SY=$(vmstat |awk 'NR==3{print $14}')
IDLE=$(vmstat |awk 'NR==3{print $15}')
WAIT=$(vmstat |awk 'NR==3{print $16}')
USE=$(($US+$SY))
if [ $USE -ge 50 ]; then
    echo "
    Date: $DATE
    Host: $IP
    Problem: CPU utilization $USE
    " | mail -s "CPU Monitor" $MAIL

memory：

#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F '[ :]+' '/inet addr/{print $4}')
MAIL="example@mail.com"
TOTAL=$(free -m |awk '/Mem/{print $2}')
USE=$(free -m |awk '/Mem/{print $3-$6-$7}')
FREE=$(($TOTAL-$USE))
# 内存小于1G发送报警邮件
if [ $FREE -lt 1024 ]; then
    echo "
    Date: $DATE
    Host: $IP
    Problem: Total=$TOTAL,Use=$USE,Free=$FREE
    " | mail -s "Memory Monitor" $MAIL

disk:

#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F '[ :]+' '/inet addr/{print $4}')
MAIL="example@mail.com"
TOTAL=$(fdisk -l |awk -F'[: ]+' 'BEGIN{OFS="="}/^Disk \/dev/{printf "%s=%sG,",$2,$3}')
PART_USE=$(df -h |awk 'BEGIN{OFS="="}/^\/dev/{print $1,int($5),$6}')
for i in $PART_USE; do
    PART=$(echo $i |cut -d"=" -f1)
    USE=$(echo $i |cut -d"=" -f2)
    MOUNT=$(echo $i |cut -d"=" -f3)
    if [ $USE -gt 80 ]; then
        echo "
        Date: $DATE
        Host: $IP
        Total: $TOTAL
        Problem: $PART=$USE($MOUNT)
        " | mail -s "Disk Monitor" $MAIL
    fi

5. 系统初始化：

#!/usr/bin/env bash
#
# Author: liuchao
# Email: liuchao07a@icloud.com
# Version: v1.0
# BeiJingQianFengHuLianKeJiYouXianGongSi.

# This script is used to set your server to initialize, and it can be used to install the necessary software,
# set your yum source, but also configure some security settings, you can also add the appropriate functionality
# to meet your needs



# Get os version.
OSRELEASE=$(rpm -q --qf "%{Version}" $(rpm -q --whatprovides redhat-release))

# Configure yum source, config is BeiJingQFcloud.
sed -ri s/^#baseurl/baseurl/g /etc/yum.repos.d/CentOS-Base.repo
sed -ri s/^mirrorlist/#mirrorlist/g /etc/yum.repos.d/CentOS.Base.repo

yum clean all
yum makecache
wait

yum -y install epel-release &>/dev/null

sed -ri s/^#baseurl/baseurl/g /etc/yum.repos.d/epel.repo
sed -ri s/^mirrorlist/#mirrorlist/g /etc/yum.repos.d/epel.repo

yum makecache
wait

# Install software.
yum -y install nc vim iftop iotop dstat tcpdump
yum -y install ipmitool bind-libs bind-utils
yum -y install libselinux-python ntpdate
yum -y install net-tools lftp

# disable unuse service.
systemctl stop auditd && systemctl disable auditd
systemctl stop firewalld && systemctl disable firewalld

# disable ipv6.
cd /etc/modprobe.d/ && touch ipv6.conf
>/etc/modprobe.d/ipv6.conf
cat >> /etc/modprobe.d/ipv6.conf <<EOF
alias net-pf-10 off
alias ipv6 off
EOF

# set route forward.
>/etc/sysctl.conf
cat >> /etc/sysctl.conf <<EOF
net.ipv4.ip_forward = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
EOF

# disable SELINUX.
setenforce 0
sed -ri s/SELINUX=enforcing/SELINUX=disabled/g /etc/selinux/config

# set history display datetime.
echo "HISTFILESIZE=2000" >> /etc/bashrc && echo "HISTSIZE=2000" >> /etc/bashrc && echo 'HISTTIMEFORMAT="%Y%m%d %T "'>> /etc/bashrc && export HISTTIMEFORMAT



6. 搭建内网yum源服务器，并定期同步公网数据

#!/bin/bash
#
# BeiJing QFcloud office made.
# author:liuchao
# 2017/8/12.

if [ -f /var/log/yum_server.pid ];then
    rm -rf /var/log/yum_server.pid
else
    echo "Ok. Continue rsync yum server." &> /dev/null
fi

YUM_SITE="rsync://mirrors.tuna.tsinghua.edu.cn/centos/"
#存放路径，我这里直接用的是httpd默认根目录
LOCAL_PATH="/var/www/html/centos/"
#需要同步哪些目录
LOCAL_VER='6 6* 7 7*'
BW_limit=2048
LOCK_FILE="/var/log/yum_server.pid"
RSYNC_PATH=""

# check update yum server pid
MY_PID=$$
if [ -f $LOCK_FILE ]; then
get_pid=`/bin/cat $LOCK_FILE`
get_system_pid=`/bin/ps -ef|grep -v grep|grep $get_pid|wc -l`
if [ $get_system_pid -eq 0 ] ; then
echo $MY_PID>$LOCK_FILE
else
echo "Have update yum server now!"
exit 1
fi
else
echo $MY_PID>$LOCK_FILE
fi

# check rsync tool
if [ -z $RSYNC_PATH ]; then
RSYNC_PATH=`/usr/bin/whereis rsync|awk ' ''{print $2}'`
if [ -z $RSYNC_PATH ]; then
echo 'Not find rsync tool.'
echo 'use comm: yum install -y rsync'
fi
fi

# sync yum source
for VER in $LOCAL_VER;
do
# Check whether there are local directory
if [ ! -d "$LOCAL_PATH$VER" ] ; then
echo "Create dir $LOCAL_PATH$VER"
`/bin/mkdir -p $LOCAL_PATH$VER`
fi
# sync yum source
echo "Start sync $LOCAL_PATH$VER"
$RSYNC_PATH -avrtH --delete --bwlimit=$BW_limit --exclude "isos" $YUM_SITE$VER $LOCAL_PATH
done

# clean lock file
`/bin/rm -f $LOCK_FILE`

echo "rsync end $(date +%Y-%m-%d_%k:%M:%S)" >> /var/www/html/centos/centos_rsync_is_end.txt
exit 1

1.使用shell脚本，判断10.18.41.0/24网络里，当前在线的IP有哪些。并对在线的主机批量传送公钥
2.使用shell脚本，获取本机的详细信息（当前用户，IP，内核版本，主机名称，CPU版本信息……）
3.请按照这样的日期格式（xxxx-xx-xx）每日生成一个文件，例如今天生成的文件为）2017-07-05.log， 并且把磁盘的使用情况
写到到这个文件中，（不用考虑cron，仅仅写脚本即可）
5.使用shell脚本进行判断磁盘，内存使用情况，当磁盘，内存使用量超过20%，就发警报进行报警（或者发报警邮件给自己）
工具分享：
top 查看进程活动状态以及一些系统状况
vmstat 查看系统状态、硬件和系统信息等
iostat 查看CPU 负载，硬盘状况
sar 综合工具，查看系统状况
mpstat 查看多处理器状况
netstat 查看网络状况
iptraf 实时网络状况监测
tcpdump 抓取网络数据包，详细分析
tcptrace 数据包分析工具
netperf 网络带宽工具