（转）30个关于Shell脚本的经典案例

2019-09-26  本文已影响0人  勇者与王者

https://www.cnblogs.com/linuxprobe/p/11518761.html

30个关于Shell脚本的经典案例（上）

| 对于初学者而言，因为没有实战经验，写不出来Shell脚本很正常，如果工作了几年的运维老年还是写不出来，那就是没主动找需求，缺乏练习，缺乏经验。针对以上问题，总结了30个生产环境中经典的Shell脚本，通过这些需求案例，希望能帮助大家提升Shell编写思路，掌握编写技巧。 |

先了解下编写Shell过程中注意事项：

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">开头加解释器：#!/bin/bash
语法缩进，使用四个空格；多加注释说明。
命名建议规则：变量名大写、局部变量小写，函数名小写，名字体现出实际作用。
默认变量是全局的，在函数中变量local指定为局部变量，避免污染其他作用域。
有两个命令能帮助我调试脚本：set -e 遇到执行非0时退出脚本，set-x 打印执行过程。
写脚本一定先测试再到生产上。
</pre>

1、获取随机字符串或数字

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">获取随机8位字符串：
方法1：

echo $RANDOM |md5sum |cut -c 1-8

471b94f2
方法2：

openssl rand -base64 4

vg3BEg==
方法3：

cat /proc/sys/kernel/random/uuid |cut -c 1-8

ed9e032c

获取随机8位数字：
方法1：

echo $RANDOM |cksum |cut -c 1-8

23648321
方法2：

openssl rand -base64 4 |cksum |cut -c 1-8

38571131
方法3：

date +%N |cut -c 1-8

69024815

cksum：打印CRC效验和统计字节
</pre>

2、定义一个颜色输出字符串函数

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">方法1：
function echo_color() {
if [ 1 == "green" ]; then echo -e "\033[32;40m2\033[0m"
elif [ 1 == "red" ]; then echo -e "\033[31;40m2\033[0m"
fi
}
方法2：
function echo_color() {
case 1 in green) echo -e "[32;40m2[0m"
;;
red)
echo -e "[31;40m$2[0m"
;;
*)
echo "Example: echo_color red string"
esac
}

使用方法：echo_color green "test"

function关键字定义一个函数，可加或不加。
</pre>

3、批量创建用户

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">#!/bin/bash
DATE=(date +%F_%T) USER_FILE=user.txt echo_color(){ if [1 == "green" ]; then
echo -e "[32;40m2[0m" elif [1 == "red" ]; then
echo -e "[31;40m$2[0m"
fi
}

如果用户文件存在并且大小大于0就备份

if [ -s USER_FILE ]; then mvUSER_FILE {USER_FILE}-{DATE}.bak
echo_color green "USER_FILE exist, rename{USER_FILE}-{DATE}.bak" fi echo -e "User Password" >>USER_FILE
echo "----------------" >> USER_FILE for USER in user{1..10}; do if ! idUSER &>/dev/null; then
PASS=(echoRANDOM |md5sum |cut -c 1-8)
useradd USER echoPASS |passwd --stdin USER &>/dev/null echo -e "USER PASS" >>USER_FILE
echo "USER User create successful." else echo_color red "USER User already exists!"
fi
done
</pre>

4、检查软件包是否安装

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">#!/bin/bash
if rpm -q sysstat &>/dev/null; then
echo "sysstat is already installed."
else
echo "sysstat is not installed!"
fi
</pre>

5、检查服务状态

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">#!/bin/bash
PORT_C=(ss -anu |grep -c 123) PS_C=(ps -ef |grep ntpd |grep -vc grep)
if [ PORT_C -eq 0 -oPS_C -eq 0 ]; then
echo "内容" | mail -s "主题" dst@example.com
fi
</pre>

6、检查主机存活状态

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">方法1：将错误IP放到数组里面判断是否ping失败三次

!/bin/bash

IP_LIST="192.168.18.1 192.168.1.1 192.168.18.2"
for IP in IP_LIST; do NUM=1 while [NUM -le 3 ]; do
if ping -c 1 IP > /dev/null; then echo "IP Ping is successful."
break
else
# echo "IP Ping is failureNUM"
FAIL_COUNT[NUM]=IP
let NUM++
fi
done
if [ {#FAIL_COUNT[*]} -eq 3 ];then echo "{FAIL_COUNT[1]} Ping is failure!"
unset FAIL_COUNT[*]
fi
done

方法2：将错误次数放到FAIL_COUNT变量里面判断是否ping失败三次

!/bin/bash

IP_LIST="192.168.18.1 192.168.1.1 192.168.18.2"
for IP in IP_LIST; do FAIL_COUNT=0 for ((i=1;i< =3;i++)); do if ping -c 1IP >/dev/null; then
echo "IP Ping is successful." break else # echo "IP Ping is failure i" let FAIL_COUNT++ fi done if [FAIL_COUNT -eq 3 ]; then
echo "$IP Ping is failure!"
fi
done

方法3：利用for循环将ping通就跳出循环继续，如果不跳出就会走到打印ping失败

!/bin/bash

ping_success_status() {
if ping -c 1 IP >/dev/null; then echo "IP Ping is successful."
continue
fi
}
IP_LIST="192.168.18.1 192.168.1.1 192.168.18.2"
for IP in IP_LIST; do ping_success_status ping_success_status ping_success_status echo "IP Ping is failure!"
done
</pre>

7、监控CPU、内存和硬盘利用率

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">1）CPU
借助vmstat工具来分析CPU统计信息。

!/bin/bash

DATE=(date +%F" "%H:%M) IP=(ifconfig eth0 |awk -F [ :]+ /inet addr/{print 4} ) # 只支持[CentOS](https://www.linuxprobe.com/ "centos")6 MAIL="example@mail.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 utilizationUSE
" | mail -s "CPU Monitor" $MAIL
fi

2）内存

!/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
fi

3）硬盘

!/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/{print1,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
done
</pre>

8、批量主机磁盘利用率监控

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">前提监控端和被监控端SSH免交互登录或者密钥登录。

写一个配置文件保存被监控主机SSH连接信息，文件内容格式：IP User Port

!/bin/bash

HOST_INFO=host.info
for IP in (awk /^[^#]/{print1} HOST_INFO); do USER=(awk -v ip=IP ip==1{print 2}HOST_INFO)
PORT=(awk -v ip=IP ip==1{print3} HOST_INFO) TMP_FILE=/tmp/disk.tmp ssh -pPORT USER@IP df -h > TMP_FILE USE_RATE_LIST=(awk BEGIN{OFS="="}/^/dev/{print 1,int(5)} TMP_FILE) for USE_RATE inUSE_RATE_LIST; do
PART_NAME={USE_RATE%=*} USE_RATE={USE_RATE#*=}
if [ USE_RATE -ge 80 ]; then echo "Warning:PART_NAME Partition usage $USE_RATE%!"
fi
done
done
</pre>

9、检查网站可用性

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">1）检查URL可用性
方法1：
check_url() {
HTTP_CODE=(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}"1)
if [ HTTP_CODE -ne 200 ]; then echo "Warning:1 Access failure!"
fi
}
方法2：
check_url() {
if ! wget -T 10 --tries=1 --spider $1 >/dev/null 2>&1; then

-T超时时间，--tries尝试1次，--spider爬虫模式

    echo "Warning: $1 Access failure!"
fi

}

使用方法：check_url www.baidu.com

2）判断三次URL可用性
思路与上面检查主机存活状态一样。

方法1：利用循环技巧，如果成功就跳出当前循环，否则执行到最后一行

!/bin/bash

check_url() {
HTTP_CODE=(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}"1)
if [ HTTP_CODE -eq 200 ]; then continue fi } URL_LIST="www.baidu.com www.agasgf.com" for URL inURL_LIST; do
check_url URL check_urlURL
check_url URL echo "Warning:URL Access failure!"
done

方法2：错误次数保存到变量

!/bin/bash

URL_LIST="www.baidu.com www.agasgf.com"
for URL in URL_LIST; do FAIL_COUNT=0 for ((i=1;i< =3;i++)); do HTTP_CODE=(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" URL) if [HTTP_CODE -ne 200 ]; then
let FAIL_COUNT++
else
break
fi
done
if [ FAIL_COUNT -eq 3 ]; then echo "Warning:URL Access failure!"
fi
done

方法3：错误次数保存到数组

!/bin/bash

URL_LIST="www.baidu.com www.agasgf.com"
for URL in URL_LIST; do NUM=1 while [NUM -le 3 ]; do
HTTP_CODE=(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}"URL)
if [ HTTP_CODE -ne 200 ]; then FAIL_COUNT[NUM]=IP #创建数组，以NUM下标，IP元素 let NUM++ else break fi done if [{#FAIL_COUNT[]} -eq 3 ]; then
echo "Warning: $URL Access failure!"
unset FAIL_COUNT[] #清空数组
fi
done
</pre>

10、检查MySQL主从同步状态

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word;">#!/bin/bash
USER=bak
PASSWD=123456
IO_SQL_STATUS=(mysql -uUSER -pPASSWD -e show slave statusG |awk -F: /Slave_.*_Running/{gsub(": ",":");print0} ) #gsub去除冒号后面的空格
for i in IO_SQL_STATUS; do THREAD_STATUS_NAME={i%:*}
THREAD_STATUS={i#*:} if [ "THREAD_STATUS" != "Yes" ]; then
echo "Error: MySQL Master-Slave THREAD_STATUS_NAME status isTHREAD_STATUS!"
fi
done
</pre>

动手练一练，让你的Shell功底上升一个段位！

本文目录

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">11、iptables自动屏蔽访问网站频繁的IP
12、判断用户输入的是否为IP地址
13、判断用户输入的是否为数字
14、给定目录找出包含关键字的文件
15、监控目录，将新创建的文件名追加到日志中
16、给用户提供多个网卡选择
17、查看网卡实时流量
18、MySQL数据库备份
19、Nginx服务管理脚本
20、用户根据菜单选择要连接的Linux主机
</pre>

11、iptables自动屏蔽访问网站频繁的IP

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">场景：恶意访问,安全防范

1）屏蔽每分钟访问超过200的IP

方法1：根据访问日志（Nginx为例）

!/bin/bash

DATE=(date +%d/%b/%Y:%H:%M) ABNORMAL_IP=(tail -n5000 access.log |grep DATE |awk '{a[1]++}END{for(i in a)if(a[i]>100)print i}')

先tail防止文件过大，读取慢，数字可调整每分钟最大的访问量。awk不能直接过滤日志，因为包含特殊字符。

for IP in ABNORMAL_IP; do if [(iptables -vnL |grep -c "IP") -eq 0 ]; then iptables -I INPUT -sIP -j DROP
fi
done
方法2：通过TCP建立的连接

!/bin/bash

ABNORMAL_IP=(netstat -an |awk '4~/:80/ &&6~/ESTABLISHED/{gsub(/:[0-9]+/,"",5);{a[5]++}}END{for(i in a)if(a[i]>100)print i}')

gsub是将第五列（客户端IP）的冒号和端口去掉

for IP in ABNORMAL_IP; do if [(iptables -vnL |grep -c "IP") -eq 0 ]; then iptables -I INPUT -sIP -j DROP
fi
done

2）屏蔽每分钟SSH尝试登录超过10次的IP

方法1：通过lastb获取登录状态:

!/bin/bash

DATE=(date +"%a %b %e %H:%M") #星期月天时分 %e单数字时显示7，而%d显示07 ABNORMAL_IP=(lastb |grep "DATE" |awk '{a[3]++}END{for(i in a)if(a[i]>10)print i}')
for IP in ABNORMAL_IP; do if [(iptables -vnL |grep -c "IP") -eq 0 ]; then iptables -I INPUT -sIP -j DROP
fi
done
方法2：通过日志获取登录状态

!/bin/bash

DATE=(date +"%b %d %H") ABNORMAL_IP="(tail -n10000 /var/log/auth.log |grep "DATE" |awk '/Failed/{a[(NF-3)]++}END{for(i in a)if(a[i]>5)print i}')"
for IP in ABNORMAL_IP; do if [(iptables -vnL |grep -c "IP") -eq 0 ]; then iptables -A INPUT -sIP -j DROP
echo "(date +"%F %T") - iptables -A INPUT -sIP -j DROP" >>~/ssh-login-limit.log
fi
done
</pre>

12、判断用户输入的是否为IP地址

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">方法1:

!/bin/bash

function check_ip(){
IP=1 VALID_CHECK=(echo IP|awk -F. '1< =255&&2<=255&&3<=255&&4<=255{print "yes"}') if echoIP|grep -E "^[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}">/dev/null; then if [VALID_CHECK == "yes" ]; then
echo "IP available." else echo "IP not available!"
fi
else
echo "Format error!"
fi
}
check_ip 192.168.1.1
check_ip 256.1.1.1
方法2：

!/bin/bash

function check_ip(){
IP=1 if [[IP =~ ^[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}]]; then FIELD1=(echo IP|cut -d. -f1) FIELD2=(echo IP|cut -d. -f2) FIELD3=(echo IP|cut -d. -f3) FIELD4=(echo IP|cut -d. -f4) if [FIELD1 -le 255 -a FIELD2 -le 255 -aFIELD3 -le 255 -a FIELD4 -le 255 ]; then echo "IP available."
else
echo "$IP not available!"
fi
else
echo "Format error!"
fi
}
check_ip 192.168.1.1
check_ip 256.1.1.1
增加版：

加个死循环，如果IP可用就退出，不可用提示继续输入，并使用awk判断。

!/bin/bash

function check_ip(){
local IP=1 VALID_CHECK=(echo IP|awk -F. '1< =255&&2<=255&&3<=255&&4<=255{print "yes"}') if echoIP|grep -E "^[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}" >/dev/null; then if [VALID_CHECK == "yes" ]; then
return 0
else
echo "IP not available!" return 1 fi else echo "Format error! Please input again." return 1 fi } while true; do read -p "Please enter IP: " IP check_ipIP
[ $? -eq 0 ] && break || continue
done
</pre>

13、判断用户输入的是否为数字

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">方法1：

!/bin/bash

if [[ 1 =~ ^[0-9]+ ]]; then
echo "Is Number."
else
echo "No Number."
fi
方法2：

!/bin/bash

if [ $1 -gt 0 ] 2>/dev/null; then
echo "Is Number."
else
echo "No Number."
fi
方法3：

!/bin/bash

echo 1 |awk '{print0~/^[0-9]+/?"Is Number.":"No Number."}' #三目运算符 12.14 找出包含关键字的文件 DIR=1
KEY=2 for FILE in(find DIR -type f); do if grepKEY FILE &>/dev/null; then echo "-->FILE"
fi
done
</pre>

14、给定目录找出包含关键字的文件

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">#!/bin/bash
DIR=1 KEY=2
for FILE in (findDIR -type f); do
if grep KEYFILE &>/dev/null; then
echo "--> $FILE"
fi
done
</pre>

15、监控目录，将新创建的文件名追加到日志中

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">场景：记录目录下文件操作。

需先安装inotify-tools软件包。

!/bin/bash

MON_DIR=/opt
inotifywait -mq --format %f -e create MON_DIR |\ while read files; do echofiles >> test.log
done
</pre>

16、给用户提供多个网卡选择

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">场景：服务器多个网卡时，获取指定网卡，例如网卡流量

!/bin/bash

function local_nic() {
local NUM ARRAY_LENGTH
NUM=0
for NIC_NAME in (ls /sys/class/net|grep -vE "lo|docker0"); do NIC_IP=(ifconfig NIC_NAME |awk -F'[: ]+' '/inet addr/{print4}')
if [ -n "NIC_IP" ]; then NIC_IP_ARRAY[NUM]="NIC_NAME:NIC_IP" #将网卡名和对应IP放到数组
let NUM++
fi
done
ARRAY_LENGTH={#NIC_IP_ARRAY[*]} if [ARRAY_LENGTH -eq 1 ]; then #如果数组里面只有一条记录说明就一个网卡
NIC={NIC_IP_ARRAY[0]%:*} return 0 elif [ARRAY_LENGTH -eq 0 ]; then #如果没有记录说明没有网卡
echo "No available network card!"
exit 1
else
#如果有多条记录则提醒输入选择
for NIC in {NIC_IP_ARRAY[*]}; do echoNIC
done
while true; do
read -p "Please enter local use to network card name: " INPUT_NIC_NAME
COUNT=0
for NIC in {NIC_IP_ARRAY[*]}; do NIC_NAME={NIC%:}
if [ NIC_NAME == "INPUT_NIC_NAME" ]; then
NIC={NIC_IP_ARRAY[COUNT]%:}
return 0
else
COUNT+=1
fi
done
echo "Not match! Please input again."
done
fi
}
local_nic
</pre>

17、查看网卡实时流量

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">适用于CentOS6操作系统。

!/bin/bash

Description: Only CentOS6

traffic_unit_conv() {
local traffic=1 if [traffic -gt 1024000 ]; then
printf "%.1f%s" "((traffic/1024/1024))" "MB/s"
elif [ traffic -lt 1024000 ]; then printf "%.1f%s" "((traffic/1024))" "KB/s" fi } NIC=1
echo -e " In ------ Out"
while true; do
OLD_IN=(awk -F'[: ]+' '0~"'NIC'"{print3}' /proc/net/dev)
OLD_OUT=(awk -F'[: ]+' '0~"'NIC'"{print11}' /proc/net/dev)
sleep 1
NEW_IN=(awk -F'[: ]+' '0~"'NIC'"{print3}' /proc/net/dev)
NEW_OUT=(awk -F'[: ]+' '0~"'NIC'"{print11}' /proc/net/dev)
IN=((NEW_IN-OLD_IN)) OUT=((NEW_OUT-OLD_OUT))
echo "(traffic_unit_convIN) (traffic_unit_convOUT)"
sleep 1
done
使用：./traffic.sh eth0
</pre>

18、MySQL数据库备份

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">#!/bin/bash
DATE=(date +%F_%H-%M-%S) HOST=192.168.1.120 DB=test USER=bak PASS=123456 MAIL="zhangsan@example.com lisi@example.com" BACKUP_DIR=/data/db_backup SQL_FILE={DB}fullDATE.sql BAK_FILE={DB}fullDATE.zip cdBACKUP_DIR
if mysqldump -hHOST -uUSER -pPASS --single-transaction --routines --triggers -BDB > SQL_FILE; then zipBAK_FILE SQL_FILE && rm -fSQL_FILE
if [ ! -s BAK_FILE ]; then echo "DATE 内容" | mail -s "主题" MAIL fi else echo "DATE 内容" | mail -s "主题" MAIL fi findBACKUP_DIR -name '*.zip' -ctime +14 -exec rm {} ;
</pre>

19、Nginx服务管理脚本

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">场景：使用源码包安装Nginx不含带服务管理脚本，也就是不能使用"service nginx start"或"/etc/init.d/nginx start"，所以写了以下的服务管理脚本。

!/bin/bash

Description: Only support RedHat system

. /etc/init.d/functions
WORD_DIR=/usr/local/nginx
DAEMON=WORD_DIR/sbin/nginx CONF=WORD_DIR/conf/nginx.conf
NAME=nginx
PID=(awk -F'[; ]+' '/^[^#]/{if(0~/pid;/)print 2}'CONF)
if [ -z "PID" ]; then PID=WORD_DIR/logs/nginx.pid
else
PID=WORD_DIR/PID
fi
stop() {
DAEMON -s stop sleep 1 [ ! -fPID ] && action "* Stopping NAME" /bin/true || action "* StoppingNAME" /bin/false
}
start() {
DAEMON sleep 1 [ -fPID ] && action "* Starting NAME" /bin/true || action "* StartingNAME" /bin/false
}
reload() {
DAEMON -s reload } test_config() {DAEMON -t
}
case "1" in start) if [ ! -fPID ]; then
start
else
echo "NAME is running..." exit 0 fi ;; stop) if [ -fPID ]; then
stop
else
echo "NAME not running!" exit 0 fi ;; restart) if [ ! -fPID ]; then
echo "NAME not running!" start else stop start fi ;; reload) reload ;; testconfig) test_config ;; status) [ -fPID ] && echo "NAME is running..." || echo "NAME not running!"
;;
*)
echo "Usage: $0 {start|stop|restart|reload|testconfig|status}"
exit 3
;;
esac</pre>

https://article.pchome.net/content-2100027.html
http://www.51cto.com/it/news/2019/0909/14338.html
https://www.linuxprobe.com/books

20、用户根据菜单选择要连接的Linux主机

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">Linux主机SSH连接信息：

cat host.txt

Web 192.168.1.10 root 22
DB 192.168.1.11 root 22
内容格式：主机名 IP User Port

!/bin/bash

PS3="Please input number: "
HOST_FILE=host.txt
while true; do
select NAME in (awk '{print1}' HOST_FILE) quit; do [{NAME:=empty} == "quit" ] && exit 0
IP=(awk -v NAME={NAME} '1==NAME{print2}' HOST_FILE) USER=(awk -v NAME={NAME} '1==NAME{print 3}'HOST_FILE)
PORT=(awk -v NAME={NAME} '1==NAME{print4}' HOST_FILE) if [IP ]; then
echo "Name: NAME, IP:IP"
ssh -o StrictHostKeyChecking=no -p PORT -i id_rsaUSER@$IP # 密钥免交互登录
break
else
echo "Input error, Please enter again!"
break
fi
done
done</pre>

本文目录

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">21、从FTP服务器下载文件
22、连续输入5个100以内的数字，统计和、最小和最大
23、将结果分别赋值给变量
24、批量修改文件名
25、统计当前目录中以.html结尾的文件总大
26、扫描主机端口状态
27、Expect实现SSH免交互执行命令
28、批量修改服务器用户密码
29、打印乘法口诀
30、getopts工具完善脚本命令行参数
</pre>

21、从FTP服务器下载文件

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">#!/bin/bash
if [ # -ne 1 ]; then echo "Usage:0 filename"
fi
dir=(dirname1)
file=(basename1)
ftp -n -v << EOF # -n 自动登录
open 192.168.1.10 # ftp服务器
user admin password
binary # 设置ftp传输模式为二进制，避免MD5值不同或.tar.gz压缩包格式错误
cd dir get "file"
EOF
</pre>

22、连续输入5个100以内的数字，统计和、最小和最大

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">#!/bin/bash
COUNT=1
SUM=0
MIN=0
MAX=100
while [ COUNT -le 5 ]; do read -p "请输入1-10个整数：" INT if [[ !INT =~ ^[0-9]+]]; then echo "输入必须是整数！" exit 1 elif [[INT -gt 100 ]]; then
echo "输入必须是100以内！"
exit 1
fi
SUM=((SUM+INT)) [MIN -lt INT ] && MIN=INT
[ MAX -gtINT ] && MAX=INT let COUNT++ done echo "SUM:SUM"
echo "MIN: MIN" echo "MAX:MAX"
</pre>

30个关于Shell脚本的经典案例（下）30个关于Shell脚本的经典案例（下）

23、将结果分别赋值给变量

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">应用场景：希望将执行结果或者位置参数赋值给变量，以便后续使用。

方法1：

for i in (echo "4 5 6"); do eval ai=i done echoa4 a5a6
方法2：将位置参数192.168.1.1{1,2}拆分为到每个变量

num=0
for i in (eval echo*);do #eval将{1,2}分解为1 2
let num+=1
eval node{num}="i"
done
echo node1node2 $node3

bash a.sh 192.168.1.1{1,2}

192.168.1.11 192.168.1.12
方法3：

arr=(4 5 6)
INDEX1=(echo{arr[0]})
INDEX2=(echo{arr[1]})
INDEX3=(echo{arr[2]})
</pre>

24、批量修改文件名

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">示例：

touch article_{1..3}.html

ls

article_1.html article_2.html article_3.html
目的：把article改为bbs

方法1：

for file in (ls *html); do mvfile bbs_{file#*_} # mvfile (echofile |sed -r 's/.(_.)/bbs\1/')
# mv file(echo file |echo bbs_(cut -d_ -f2)
done
方法2：

for file in (find . -maxdepth 1 -name "*html"); do mvfile bbs_${file#*_}
done
方法3：

rename article bbs *.html

</pre>

25、统计当前目录中以.html结尾的文件总大

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">方法1：

find . -name "*.html" -exec du -k {} ; |awk '{sum+=$1}END{print sum}'

方法2：

for size in (ls -l *.html |awk '{print5}'); do
sum=((sum+size)) done echosum
</pre>

26、扫描主机端口状态

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">#!/bin/bash
HOST=1 PORT="22 25 80 8080" for PORT inPORT; do
if echo &>/dev/null > /dev/tcp/HOST/PORT; then
echo "PORT open" else echo "PORT close"
fi
done
</pre>

27、Expect实现SSH免交互执行命令

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">Expect是一个自动交互式应用程序的工具，如telnet，ftp，passwd等。

需先安装expect软件包。

方法1：EOF标准输出作为expect标准输入

!/bin/bash

USER=root
PASS=123.com
IP=192.168.1.120
expect << EOF
set timeout 30
spawn ssh USER@IP
expect {
"(yes/no)" {send "yes\r"; exp_continue}
"password:" {send "PASS\r"} } expect "USER@" {send "1\r"} expect "USER@" {send "exit\r"}
expect eof
EOF
方法2：

!/bin/bash

USER=root
PASS=123.com
IP=192.168.1.120
expect -c "
spawn ssh USER@IP
expect {
"(yes/no)" {send "yes\r"; exp_continue}
"password:" {send "PASS\r\"; exp_continue} \"USER@*" {send "df -h\r exit\r"; exp_continue}
}"
方法3：将expect脚本独立出来

登录脚本：

cat login.exp

!/usr/bin/expect

set ip [lindex argv 0] set user [lindexargv 1]
set passwd [lindex argv 2] set cmd [lindexargv 3]
if { argc != 4 } { puts "Usage: expect login.exp ip user passwd" exit 1 } set timeout 30 spawn sshuser@ip expect { "(yes/no)" {send "yes\r"; exp_continue} "password:" {send "passwd\r"}
}
expect "user@*" {send "cmd\r"}
expect "$user@*" {send "exit\r"}
expect eof
执行命令脚本：写个循环可以批量操作多台服务器

!/bin/bash

HOST_INFO=user_info.txt
for ip in (awk '{print1}' HOST_INFO) do user=(awk -v I="ip" 'I==1{print 2}'HOST_INFO)
pass=(awk -v I="ip" 'I==1{print3}' HOST_INFO) expect login.expip userpass $1
done
Linux主机SSH连接信息：

cat user_info.txt

192.168.1.120 root 123456
</pre>

28、批量修改服务器用户密码

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">Linux主机SSH连接信息：旧密码

cat old_pass.txt

192.168.18.217 root 123456 22
192.168.18.218 root 123456 22
内容格式：IP User Password Port

SSH远程修改密码脚本：新密码随机生成
https://www.linuxprobe.com/books

!/bin/bash

OLD_INFO=old_pass.txt
NEW_INFO=new_pass.txt
for IP in (awk '/^[^#]/{print1}' OLD_INFO); do USER=(awk -v I=IP 'I==1{print 2}'OLD_INFO)
PASS=(awk -v I=IP 'I==1{print3}' OLD_INFO) PORT=(awk -v I=IP 'I==1{print 4}'OLD_INFO)
NEW_PASS=(mkpasswd -l 8) # 随机密码 echo "IP USERNEW_PASS PORT" >>NEW_INFO
expect -c "
spawn ssh -pPORTUSER@IP set timeout 2 expect { \"(yes/no)\" {send \"yes\r\";exp_continue} \"password:\" {send \"PASS\r";exp_continue}
"USER@*\" {send \"echo \'NEW_PASS' |passwd --stdin $USER\r exit\r";exp_continue}
}"
done
生成新密码文件：

cat new_pass.txt

192.168.18.217 root n8wX3mU% 22
192.168.18.218 root c87;ZnnL 22
</pre>

29、打印乘法口诀

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">方法1：

awk 'BEGIN{for(n=0;n++<9;){for(i=0;i++<n;)printf i"x"n"="i*n" ";print ""}}'

方法2：

for ((i=1;i<=9;i++)); do
for ((j=1;j<=i;j++)); do
result=((ij)) echo -n "ji=result "
done
echo
done
</pre>

30、getopts工具完善脚本命令行参数

<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; overflow-wrap: break-word; color: rgb(51, 51, 51); font-size: 14px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial;">getopts是一个解析脚本选项参数的工具。

命令格式：getopts optstring name [arg]

初次使用你要注意这几点：

脚本位置参数会与optstring中的单个字母逐个匹配，如果匹配到就赋值给name，否则赋值name为问号；

optstring中单个字母是一个选项，如果字母后面加冒号，表示该选项后面带参数，参数值并会赋值给OPTARG变量；

optstring中第一个是冒号，表示屏蔽系统错误（test.sh: illegal option -- h）；

允许把选项放一起，例如-ab

下面写一个打印文件指定行的简单例子，引导你思路：

!/bin/bash

while getopts :f:n: option; do
case option in f) FILE=OPTARG
[ ! -f FILE ] && echo "FILE File not exist!" && exit
;;
n)
sed -n "{OPTARG}p"FILE
;;
?)
echo "Usage: $0 -f -n "
echo "-f, --file specified file"
echo "-n, --line-number print specified line"
exit 1
;;
esac
done
</pre>

30个关于Shell脚本的经典案例（下）30个关于Shell脚本的经典案例（下）

根据工作经验总结的30个Shell脚本案例至此完结，都还是比较实用的，面试笔试题也经常会出。希望朋友们多动手练一练，让你的Shell功底上升一个段位！

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