10个常用的shell脚本

Posted 2021-04-24 云探索网络

注意事项

1）开头加解释器：#!/bin/bash

2）语法缩进，使用四个空格；多加注释说明。

3）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。

4）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。

5）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。

6）写脚本一定先测试再到生产上。

1 获取随机字符串或数字

获取随机8位字符串：

class="">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：

 class="">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

2 定义一个颜色输出字符串函数

 class="">方法1：
function echo_color() {
 if [ $1 == "green" ]; then
 echo -e "\033[32;40m$2\033[0m"
 elif [ $1 == "red" ]; then
 echo -e "\033[31;40m$2\033[0m"
 fi
}
方法2：
function echo_color() {
 case $1 in
 green)
 echo -e "\033[32;40m$2\033[0m"
 ;;
 red)
 echo -e "\033[31;40m$2\033[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。

3 批量创建用户

 class="">#!/bin/bash
DATE=$(date +%F_%T)
USER_FILE=user.txt
echo_color(){
 if [ $1 == "green" ]; then
 echo -e "\033[32;40m$2\033[0m"
 elif [ $1 == "red" ]; then
 echo -e "\033[31;40m$2\033[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
 mv $USER_FILE ${USER_FILE}-${DATE}.bak
 echo_color green "$USER_FILE exist, rename ${USER_FILE}-${DATE}.bak"
fi
echo -e "User\tPassword" >> $USER_FILE
echo "----------------" >> $USER_FILE
for USER in user{1..10}; do
 if ! id $USER &>/dev/null; then
 PASS=$(echo $RANDOM |md5sum |cut -c 1-8)
 useradd $USER
 echo $PASS |passwd --stdin $USER &>/dev/null
 echo -e "$USER\t$PASS" >> $USER_FILE
 echo "$USER User create successful."
 else
 echo_color red "$USER User already exists!"
 fi
done

4 检查软件包是否安装

 class="">#!/bin/bash
if rpm -q sysstat &>/dev/null; then
 echo "sysstat is already installed."
else
 echo "sysstat is not installed!"
fi

5 检查服务状态

 class="">#!/bin/bash
PORT_C=$(ss -anu |grep -c 123)
PS_C=$(ps -ef |grep ntpd |grep -vc grep)
if [ $PORT_C -eq 0 -o $PS_C -eq 0 ]; then
 echo "内容" | mail -s "主题" [e-mail]
fi

6 检查主机存活状态

方法1：将错误IP放到数组里面判断是否ping失败三次

 class="">#!/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 failure $NUM"
 FAIL_COUNT[$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

 class="">#!/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 1 $IP >/dev/null; then
 echo "$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

 class="">#!/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

7 监控CPU、内存和硬盘利用率

1）CPU

借助vmstat工具来分析CPU统计信息。

 class="">#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F [ :]+ /inet addr/{print $4}) # 只支持CentOS6
MAIL="[e-mail]"
if ! which vmstat &>/dev/null; then
 echo "vmstat command no found, Please install procps package." 
 exit 1
fi
US=$(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
fi

2）内存

 class="">#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F [ :]+ /inet addr/{print $4}) 
MAIL="[e-mail]"
TOTAL=$(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

 class="">#!/bin/bash
DATE=$(date +%F" "%H:%M)
IP=$(ifconfig eth0 |awk -F [ :]+ /inet addr/{print $4}) 
MAIL="[e-mail]"
TOTAL=$(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
done
>

8 批量主机磁盘利用率监控

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

 class="">#!/bin/bash
HOST_INFO=host.info
for IP in $(awk /^[^#]/{print $1} $HOST_INFO); do
 USER=$(awk -v ip=$IP ip==$1{print $2} $HOST_INFO)
 PORT=$(awk -v ip=$IP ip==$1{print $3} $HOST_INFO)
 TMP_FILE=/tmp/disk.tmp
 ssh -p $PORT $USER@$IP df -h > $TMP_FILE
 USE_RATE_LIST=$(awk BEGIN{OFS="="}/^\/dev/{print $1,int($5)} $TMP_FILE)
 for USE_RATE in $USE_RATE_LIST; do
 PART_NAME=${USE_RATE%=*}
 USE_RATE=${USE_RATE#*=}
 if [ $USE_RATE -ge 80 ]; then
 echo "Warning: $PART_NAME Partition usage $USE_RATE%!"
 fi
 done
done

9 检查网站可用性

1）检查URL可用性

 class="">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。

 class="">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 in $URL_LIST; do
 check_url $URL
 check_url $URL
 check_url $URL
 echo "Warning: $URL Access failure!"
done

---

 class="">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

---

 class="">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

10 检查MySQL主从同步状态

 class="">#!/bin/bash 
USER=bak
PASSWD=123456
IO_SQL_STATUS=$(mysql -u$USER -p$PASSWD -e show slave status\G |awk -F: /Slave_.*_Running/{gsub(": ",":");print $0}) #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 is $THREAD_STATUS!"
 fi
done

本章写的Shell脚本例子都比较实用，在面试题中也经常出现，希望大家参考着多动手写写，不要复制粘贴就拿来跑，这样是学不会的！