注意事项1）开头加解释器：#!/bin/bash，下面我们就来聊聊关于17 个实用shell 脚本?接下来我们就一起去了解一下吧!
17 个实用shell 脚本
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 1-8471b94f2方法2：# openssl rand -base64 4vg3BEg==方法3：# cat /proc/sys/kernel/random/uuid |cut -c 1-8ed9e032c
获取随机8位数字：
class="">方法1：# echo $RANDOM |cksum |cut -c 1-823648321方法2：# openssl rand -base64 4 |cksum |cut -c 1-838571131方法3：# date %N |cut -c 1-869024815
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$2\033[0m" ;; *) echo "Example: echo_color red string" esac}使用方法：echo_color green "test"
function关键字定义一个函数，可加或不加。
3 批量创建用户
class="">#!/bin/bashDATE=$(date %F_%T)USER_FILE=user.txtecho_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"fiecho -e "User\tPassword" >> $USER_FILEecho "----------------" >> $USER_FILEfor 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 "$USER User already exists!" fidone
4 检查软件包是否安装
class="">#!/bin/bashif rpm -q sysstat &>/dev/null; then echo "sysstat is already installed."else echo "sysstat is not installed!"fi
5 检查服务状态
class="">#!/bin/bashPORT_C=$(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.comfi
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[*] fidone
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!" fidone
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/bashping_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/bashDATE=$(date %F" "%H:%M)IP=$(ifconfig eth0 |awk -F '[ :] ' '/inet addr/{print $4}') # 只支持CentOS6MAIL="example@mail.com"if ! which vmstat &>/dev/null; then echo "vmstat command no found, Please install procps package." exit 1fiUS=$(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" $MAILfi
2）内存
class="">#!/bin/bashDATE=$(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" $MAILfi
3）硬盘
class="">#!/bin/bashDATE=$(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 fidone>
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/bashHOST_INFO=host.infofor 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 $USE_RATE%!" fi donedone
9 检查网站可用性
1）检查URL可用性
class="">方法1：check_url() { HTTP_CODE=$(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!" fidone
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: $URL Access failure!" unset FAIL_COUNT[*] #清空数组 fidone
10 检查MySQL主从同步状态
class="">#!/bin/bash USER=bakPASSWD=123456IO_SQL_STATUS=$(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!" fidone
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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