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:
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 "\033[32;40m$2\033[0m"
- ;;
- red)
- echo -e "\033[31;40m$2\033[0m"
- ;;
- *)
- echo "Example: echo_color red string"
- esac
- }
使用方法: echo_color green "test"
function 关键字定义一个函数, 可加或不加.
3. 批量创建用户
- #!/bin/bash
- DATE=$(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 "$USER User already exists!"
- fi
- done
4. 检查软件包是否安装
- #!/bin/bash
- if rpm -q sysstat &>/dev/null; then
- echo "sysstat is already installed."
- else
- echo "sysstat is not installed!"
- fi
5. 检查服务状态
- #!/bin/bash
- PORT_C=$(ss -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
- #!/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
- #!/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
- #!/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.
- #!/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" $MAIL
- fi
2) 内存
- #!/bin/bash
- DATE=$(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" $MAIL
- fi
3) 硬盘
- #!/bin/bash
- DATE=$(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
- #!/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 $USE_RATE%!"
- fi
- done
- done
9. 检查网站可用性
1) 检查 URL 可用性
方法 1:
- check_url() {
- HTTP_CODE=$(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: $1 Access failure!"
- fi
}
使用方法: check_url www.baidu.com
2) 判断三次 URL 可用性
思路与上面检查主机存活状态一样.
方法 1: 利用循环技巧, 如果成功就跳出当前循环, 否则执行到最后一行
- #!/bin/bash
- check_url() {
- HTTP_CODE=$(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
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
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: $URL Access failure!"
- unset FAIL_COUNT[*] #清空数组
- fi
- done
10. 检查 MySQL 主从同步状态
- #!/bin/bash
- USER=bak
- PASSWD=123456
- IO_SQL_STATUS=$(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!
来源: https://juejin.im/post/5bf512d85188252ea66ae21c