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 1-8

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

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[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 "[32;40m$2[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。

3、批量创建用户

#!/bin/bash

DATE=$(date +%F_%T)

USER_FILE=user.txt

echo_color(){

if [ $1 == 'green' ]; then

echo -e "[32;40m$2[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

mv $USER_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 ! id $USER &>/dev/null; then

PASS=$(echo $RANDOM |md5sum |cut -c 1-8)

useradd $USER

echo $PASS |passwd --stdin $USER &> /dev/dell

echo -e "$USER $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

#!/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

#!/bin/bash

PORT_C=$(ss -ant |grep -c 6443)

PS_C=$(ps -ef |grep kube-apiserver |grep -vc grep)

if [ $PORT_C -eq 0 -o $PS_C -eq 0 ]; then

echo "kube-apiserver service dowmped"

else

echo "kube-apiserver service running!"

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

#!/bin/bash

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

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

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

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

}

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

#!/bin/bash

DATE=$(date +%F" "%H:%M)

IP=$(ifconfig eth0 |awk '/netmask/ {print $2}')

if ! which vmstat &> /dev/null; then

echo "vmstat command no found, Please install procps package."

exit 1

fi

## CPU

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 $15}')

USE=$(($US+$SY))

if [ $USE -ge 50 ];then

echo "

Date: $DATE

Host: $IP

Problem: CPU utilization $USE"

fi

## Mem

TOTAL=$(free -m |awk '/Mem/ {print $2}')

USE=$(free -m |awk '/Mem/ {print $3}')

FREE=$(free -m |awk '/Mem/ {print $4+$6}')

if [ $FREE -lt 1024 ]; then

echo "

Date: $DATE

Host: $IP

Problem: Total=$TOTAL,Use=$USE,Free=$FREE"

fi

#disk

PART_USE=$(df -h |awk -F'[% ]+' 'BEGIN{OFS="="} /^\/dev/ {print $1,$2,$5,$6}')

for i in $PART_USE; do

PART=$(echo $i |cut -d"=" -f1)

TOTAL=$(echo $i |cut -d "=" -f2)

USE=$(echo $i |cut -d"=" -f3)

MOUNT=$(echo $i |cut -d"=" -f4)

if [ $USE -gt 80 ]; then

echo "

Date: $DATE

Host: $IP

Total: $TOTAL

Problem: $PART=$USE($MOUNT)"

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

#!/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 $NF,int($5)}' $TMP_FILE)

for USE_RATE in $USE_RATE_LIST; do

PART_NAME=${USE_RATE%=*} ##从右到左，非贪婪匹配，匹配到的删除

USE_RATE=${USE_RATE#*=} ##从左到右，非贪婪匹配，匹配到的删除

if [ $USE_RATE -ge 10 ];then

echo "Warning: $IP $PART_NAME Partition usage $USE_RATE%!"

fi

done

done

9、检查网站可用性

#!/bin/bash

#--------------------

#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_2() {

if ! wget -T 10 --tries=1 --spider $1 &>/dev/null; then

#-T超时时间，--tries尝试1次，--spider爬虫模式

echo "Warning: $1 Access failure!"

fi

}

#check_url www.baidu.com

#check_url_2 www.aaaa.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。

#---------------------------------

URL_LIST="www.baidu.com www.agasgf.com"

#------

#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

check_url_3() {

HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}" $1)

if [ $HTTP_CODE -eq 200 ]; then

continue

fi

}

for URL in $URL_LIST; do

check_url_3 $URL

check_url_3 $URL

check_url_3 $URL

echo "Warning: $URL Access failure!"

done

#------

#方法2：错误次数保存到变量

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

for URL in $URL_LIST;do

NUM=1

unset FAIL_COUNT

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[$NUM]=$URL

let NUM++

else

break

fi

done

if [ ${#FAIL_COUNT[@]} -eq 3 ];then

echo "Warning: $URL Access failure!"

fi

done

10、检查MySQL主从同步状态

#!/bin/bash

USER=bak

PASSWD=123456

IO_SQL_STATUS=$(mysql -u$USER -p$PASSWD -e show 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!"

fi

done