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：
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。1、获取随机字符串或数字
获取随机8位字符串：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：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 1-869024815cksum：打印CRC效验和统计字节2、定义一个颜色输出字符串函数
方法1：function echo_color() { if [ $1 == "green" ]; then echo -e "\033; then echo -e "\0333、批量创建用户
#!/bin/bashDATE=$(date +%F_%T)USER_FILE=user.txtecho_color(){ if [ $1 == "green" ]; then echo -e "; then echo -e "; then mv $USER_FILE ${USER_FILE}-${DATE}.bak echo_color green "$USER_FILE exist, rename ${USER_FILE}-${DATE}.bak"fiecho -e "User Password" >> $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 $PASS" >> $USER_FILE echo "$USER User create successful." else echo_color red "$USER User already exists!" fidone4、检查软件包是否安装
#!/bin/bashif rpm -q sysstat &>/dev/null; then echo "sysstat is already installed."else echo "sysstat is not installed!"fi5、检查服务状态
#!/bin/bashPORT_C=$(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.comfi6、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#!/bin/bashIP_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} 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#!/bin/bashIP_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#!/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!"done7、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。#!/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 |awkNR==3{print $13} )SY=$(vmstat |awkNR==3{print $14} )IDLE=$(vmstat |awkNR==3{print $15} )WAIT=$(vmstat |awkNR==3{print $16} )USE=$(($US+$SY))if [ $USE -ge 50 ]; then echo " Date: $DATE Host: $IP Problem: CPU utilization $USE " | mail -s "CPU Monitor" $MAILfi2）内存#!/bin/bashDATE=$(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" $MAILfi3）硬盘#!/bin/bashDATE=$(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 |awkBEGIN{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 fidone8、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#!/bin/bashHOST_INFO=host.infofor IP in $(awk/^[^#]/{print $1}$HOST_INFO); do USER=$(awk -v ip=$IPip==$1{print $2}$HOST_INFO) PORT=$(awk -v ip=$IPip==$1{print $3}$HOST_INFO) TMP_FILE=/tmp/disk.tmp ssh -p $PORT $USER@$IPdf -h> $TMP_FILE USE_RATE_LIST=$(awkBEGIN{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 $USE_RATE%!" fi donedone9、检查网站可用性
1）检查URL可用性方法1：check_url() { HTTP_CODE=$(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: $1 Access failure!" fi}使用方法：check_url www.baidu.com2）判断三次URL可用性思路与上面检查主机存活状态一样。方法1：利用循环技巧，如果成功就跳出当前循环，否则执行到最后一行#!/bin/bashcheck_url() { HTTP_CODE=$(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 方法2：错误次数保存到变量#!/bin/bashURL_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 方法3：错误次数保存到数组#!/bin/bashURL_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: $URL Access failure!" unset FAIL_COUNT[*] #清空数组 fidone10、检查MySQL主从同步状态
#!/bin/bashUSER=bakPASSWD=123456IO_SQL_STATUS=$(mysql -u$USER -p$PASSWD -eshow slave statusG|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动手练一练，让你的Shell功底上升一个段位！未完待续...本文地址：https://www.linuxprobe.com/shell-script-top.html编辑：传棋，审核员：逄增宝Linux命令大全：https://www.linuxcool.com/
{:6_267:}{:6_267:}{:6_267:}{:6_267:}{:6_267:}{:6_267:} {:6_267:}{:6_267:} 感谢分享 哇！好棒的东东，感谢分享啊。 111111111 666 厉害厉害
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