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原标题:10个实战及面试常用Linux Shell脚本编写
作者:李振良
来自:http://blog.51cto.com/lizhenliang/1929044
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:
functionecho_color() {
if[ $1== "green"]; then
echo-e "[32;40m$2[0m"
elif[ $1== "red"]; then
echo-e "[31;40m$2[0m"
fi
}
方法2:
functionecho_color() {
case$1in
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_FILEexist, rename ${USER_FILE}-${DATE}.bak"
fi
echo-e "User Password">> $USER_FILE
echo"----------------">> $USER_FILE
forUSER inuser{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">> $USER_FILE
echo"$USERUser create successful."
else
echo_color red "$USERUser already exists!"
fi
done
4、检查软件包是否安装#!/bin/bash
ifrpm -q sysstat &>/dev/null; then
echo"sysstat is already installed."
else
echo"sysstat is not installed!"
fi
5、检查服务状态#!/bin/bash
PORT_C=$(ss -anu |grep -c 123)
PS_C=$(ps -ef |grep ntpd |grep -vc grep)
if[ $PORT_C-eq 0 -o $PS_C-eq 0 ]; then
echo"内容"| mail -s "主题"dst@example.com
fi
6、检查主机存活状态方法1:将错误IP放到数组里面判断是否ping失败三次#!/bin/bash
IP_LIST= "192.168.18.1 192.168.1.1 192.168.18.2"
forIP in$IP_LIST; do
NUM=1
while[ $NUM-le 3 ]; do
ifping -c 1 $IP> /dev/null; then
echo"$IPPing is successful."
break
else
# echo "$IP Ping is failure $NUM"
FAIL_COUNT[ $NUM]= $IP
letNUM++
fi
done
if[ ${#FAIL_COUNT[*]}-eq 3 ]; then
echo"${FAIL_COUNT[1]}Ping is failure!"
unsetFAIL_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"
forIP in$IP_LIST; do
FAIL_COUNT=0
for((i=1;i<=3;i++)); do
ifping -c 1 $IP>/dev/null; then
echo"$IPPing is successful."
break
else
# echo "$IP Ping is failure $i"
letFAIL_COUNT++
fi
done
if[ $FAIL_COUNT-eq 3 ]; then
echo"$IPPing 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() {
ifping -c 1 $IP>/dev/null; then
echo"$IPPing is successful."
continue
fi
}
IP_LIST= "192.168.18.1 192.168.1.1 192.168.18.2"
forIP in$IP_LIST; do
ping_success_status
ping_success_status
ping_success_status
echo"$IPPing 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 $4}') # 只支持CentOS6
MAIL= "example@mail.com"
if! whichvmstat &>/dev/null; then
echo"vmstat command no found, Please install procps package."
exit1
fi
US=$(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),$6}')
fori in$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
forIP 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)
forUSE_RATE in$USE_RATE_LIST; do
PART_NAME= ${USE_RATE%=*}
USE_RATE= ${USE_RATE#*=}
if[ $USE_RATE-ge 80 ]; then
echo"Warning: $PART_NAMEPartition 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: $1Access 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: $1Access failure!"
fi
}
使用方法:check_url www.baidu.com
2)判断三次URL可用性
思路与上面检查主机存活状态一样。
方法1:利用循环技巧,如果成功就跳出当前循环,否则执行到最后一行
#!/bin/bash
check_url() {
HTTP_CODE=$(curl -o /dev/null --connect-timeout 3 -s -w "%{http_code}"$1)
if[ $HTTP_CODE-eq 200 ]; then
continue
fi
}
URL_LIST= "www.baidu.com www.agasgf.com"
forURL in$URL_LIST; do
check_url $URL
check_url $URL
check_url $URL
echo"Warning: $URLAccess failure!"
done
方法2:错误次数保存到变量
#!/bin/bash
URL_LIST= "www.baidu.com www.agasgf.com"
forURL in$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
letFAIL_COUNT++
else
break
fi
done
if[ $FAIL_COUNT-eq 3 ]; then
echo"Warning: $URLAccess failure!"
fi
done
方法3:错误次数保存到数组
#!/bin/bash
URL_LIST= "www.baidu.com www.agasgf.com"
forURL in$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
letNUM++
else
break
fi
done
if[ ${#FAIL_COUNT[*]}-eq 3 ]; then
echo"Warning: $URLAccess failure!"
unsetFAIL_COUNT[*] #清空数组
fi
done
10、检查MySQL主从同步状态#!/bin/bash
USER=bak
PASSWD=123456
IO_SQL_STATUS=$(mysql -u $USER-p $PASSWD-e 'show slave statusG'|awk -F: '/Slave_.*_Running/{gsub(": ",":");print $0}') #gsub去除冒号后面的空格
fori in$IO_SQL_STATUS; do
THREAD_STATUS_NAME= ${i%:*}
THREAD_STATUS= ${i#*:}
if[ "$THREAD_STATUS"!= "Yes"]; then
echo"Error: MySQL Master-Slave $THREAD_STATUS_NAMEstatus 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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