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10个常用的shell脚本

  • 作者: 老贱丶
  • 来源: 51数据库
  • 2022-09-21
导读 Shell是一个命令行解释器，它为用户提供了一个向Linux内核发送请求以便运行程序的界面系统级程序，用户可以用Shell来启动、挂起、停止甚至是编写一些程序。简单来讲，Shell是连接用户与内核的桥梁，是用户与内核交流的工具。
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"?dst@example.com
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?$4}')??#?只支持CentOS6
MAIL="example@mail.com"
if?!?which?vmstat?&>/dev/null;?then
????echo?"vmstat?command?no?found,?Please?install?procps?package."?
????exit?1
fi
US=$(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:?$IP
????Problem:?CPU?utilization?$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?$4}')??
MAIL="example@mail.com"
TOTAL=$(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

 class="">#!/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
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！

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