Bash shell编程实例

Linux运维之Shell编程实例

题目1：监控MySQL错误码及主从复制同步异常；

监控MySQL主从同步是否异常，如果异常，则发送短信或者邮件给管理员。提示：如果没主从同步环境,可以用下面文本放到文件里读取来模拟：
阶段1：开发一个守护进程脚本每30秒实现检测一次；
阶段2：如果同步出现如下错误号（1158,1159,1008,1007,1062），则跳过错误；
阶段3：请使用数组技术实现上述脚本（获取主从判断及错误号部分）。

阶段1：
*/2 * * * * user /PATH/TO/SCRIPT

阶段2：监控MySQL-----过滤错误码；

#!/bin/bash
CONTACT='root@node77'
ERR_LOG='/var/log/mariadb/mariadb.log'

yum install mailx -y
email_to_admin() {
mailsubject="MySQL Error."
mailbody="`date +%F-%H:%M:%S`: MySQL Error,please check and repair."
echo $mailbody | mail -s "$mailsubject" $CONTACT
}

while true;do
for ERROR_CODE in `grep 'Error_code: [[:digit:]]\+' $ERR_LOG | grep -o '[[:digit:]]\+'` ;do
case $ERROR_CODE in
1007)
continue
;;
1008)
continue
;;
1158)
continue
;;
1159)
continue
;;
1162)
continue
;;
esac
email_to_admin
done
sleep 30
done

阶段3：监控MySQL-----主从同步；

#!/bin/bash
DB_USER='root'
DB_PASSWORD='cured'
DB_PORT='3306'
MASTER='192.168.0.76'
SLAVE='192.168.0.77'
CMD_CONN_MASTER='mysql -u$DB_USER -p$DB_PASSWORD -P$DB_PORT -h$MASTER'
CMD_CONN_SLAVE='mysql -u$DB_USER -p$DB_PASSWORD' -P$DB_PORT -h$SLAVE'
CONTACT='root@node77'

declare -a master_status
master_status[0]="CMD_CONN_MASTER -e 'show master status\G' | egrep File | cut -d: -f2"
master_status[1]="CMD_CONN_MASTER -e 'show master status\G' | egrep Position | cut -d: -f2"

declare -a slave_status
slave_status[0]="CMD_CONN_SLAVE -e 'show slave status\G' | egrep Master_Log_File | cut -d: -f2"
slave_status[1]="CMD_CONN_SLAVE -e 'show slave status\G' | egrep Read_Master_Log_Pos | cut -d: -f2"
slave_status[2]="CMD_CONN_SLAVE -e 'show slave status\G' | egrep Last_Errno | cut -d: -f2"

email_to_admin() {
mailsubject="Syncing failed."
mailbody="`date '+%F %H:%M:%S'`: Syncing of master-slave is failed,please check and repair."
echo $mailbody | mail -s "$mailsubject" $CONTACT
}

while true ; do
if [ ${master_status[0]} == ${slave_status[0]} -a ${master_status[1]} == ${slave_status[1]} -a ${slave_status[2]} == 0 ]; then
echo "Syncing of master-slave is OK."
else
echo "Syncing of master-slave is failed."
email_to_admin
fi
sleep 30
done

题目2：批量创建、重命名文件；
（1）使用for循环在/heros目录下通过随机小写10个字母加固定字符串_yangkang批量创建10个html文件，名称例如为：
（2）将上述各文件名中的yangkang改为yangguo，并将html改成大写。

#!/bin/bash
#批量创建随机名称的文件
HTML_DIR=/heros
[ ! -d $PATH ] && mkdir $HTML_DIR
#yum isntall coreutils -y
#[ ! -d $PATH ] && install -m 700 -d $HTML_DIR
#使用install创建目录时，需安装coreutils。
cd $HTML_DIR && for i in `seq 10` ; do touch `openssl rand -base64 64 | tr -dc a-z | head -c 10`_yangkang.html; done

#!/bin/bash
#批量重命名文件
HTML_DIR=/heros
FILES=`ls $HTML_DIR`
GUO=guo.HTML
YANGGUO=_yangguo.HTML

cd $HTML_DIR && for j in $FILES; do
CHARS=`echo $j | cut -c 1-15`
mv $CHARS* $CHARS$GUO
done

cd $HTML_DIR && for j in $FILES; do
CHARS=`echo $j | awk -F '_' '{print$1}'`
mv $CHARS* $CHARS$YANGGUO
done

类似题目：批量创建用户；
批量创建10个系统帐号user01-user10,并设置密码为随机8位字符串。

#!/bin/bash
#批量创建用户，密码随机
for i in {01..10}; do
PASSWORD=`tr -dc [:alpha:] < /dev/urandom | head -c 8`
#PASSWORD=`openssl rand -base64 16 | tr -dc [[:alpha:]] | head -c 8`
useradd user$i
echo $PASSWORD | passwd --stdin user$i
echo user$i-----$PASSWORD >> /tmp/user-pwd.txt
done

for j in {01..10}; do userdel -r user$j; done

题目3：判断在线主机；
写一个脚本，实现判断10.0.0.0/24网络里，当前在线用户的IP有哪些。

#!/bin/bash
#

declare -i i=1
declare -i online
declare -i offline
net="10.0.0."

while [ i -le 254 ]; do
ping $net$i -c2 -w2 &> /dev/null
if [ $? -eq 0 ];then
echo "$net$i is on-line."
let online++
else
echo "$net$i is off-line."
let offline++
fi
let i++
done

echo "NO. of on-line hosts: $online ."
echo "NO. of off-line hosts: $offline ."

题目4：监控并发连接；
写一个脚本解决DOS攻击生产案例。
提示：根据web日志或者或者网络连接数，监控当某个IP并发连接数或者短时内PV达到100，即调用防火墙命令封掉对应的IP，监控频率每隔3分钟。防火墙命令为：iptables -I INPUT -s 10.0.1.10 -j DROP。

#!/bin/bash

IPlist=`netstat -ntu | awk 'NR>2' | awk '{print $5}' | cut -d: -f1 | uniq -c | sort | awk '{if($1>99)print $2}'`
#测试时，使用的并发连接为2，实际生产可将NR>2改为>100；

for ip in $IPlist; do
iptables -I INPUT -s $ip -j DROP
echo "$IPlist is dropped."
sleep 180
done

题目5：服务启动脚本；
开发mysql多实例启动脚本：
已知mysql多实例启动命令为：mysqld_safe--defaults-file=/data/3306/my.cnf &
停止命令为：mysqladmin -u$MYSQL_USER -p$MYSQL_PASSWORD -S /data/3306/mysql.sock shutdown
请完成mysql多实例启动启动脚本的编写。
要求：用函数，case语句、if语句等实现。

#!/bin/bash
. /etc/init.d/functions

declare -a PORT
PORT=(3306 3307 3308 3309 3310)
MYSQL_SOCK=/data/$PORT/mysql.sock

for i in (3306..3310); do echo $i; done

start() {
if [ ! e "MYSQL_SOCK" ]; then
nohub mysqld_safe--defaults-file=/data/${PORT[$i]}/my.cnf > /dev/null 2>&1 &
ss -tun | grep :${PORT[$i]}
if [ $? -eq 0 ]; then
action "Mysql of ${PORT[$i]} is listening." /bin/true
else
action "Mysql of ${PORT[$i]} isn't listening" /bin/false
fi
else
action "Mysql of ${PORT[$i]} is listening already." /bin/false

}

stop() {
if [ e "MYSQL_SOCK" ]; then
nohub mysqladmin -u$MYSQL_USER -p$MYSQL_PASSWORD -S /data/$PORT/mysql.sock shutdown > /dev/null 2>&1 &
ss -tun | grep :$PORT{PORT[$i]}
if [ $? -ne 0 ]; then
action "Mysql of $PORT has been stopped." /bin/true
else
action "Mysql of $PORT is still listening." /bin/false
fi
else
action "Mysql of $PORT has been stopped already." /bin/false

}

case "$1" in
start)
start
;;
stop)
stop
;;
restart)
stop
start
;;
*)
echo "Usage:$0 {3306|3307|3308|3309|3310}{start|stop|restart}"
;;
esac

类似题目：rsyncd服务启动脚本；
撰写脱离xinetd服务，独立进程运行模式下rsync的服务启动脚本；
例如：/etc/init.d/rsyncd{start|stop|restart}
要求：使用函数、可被chkconfig管理；

#!/bin/bash
# chkconfig: 2345 75 25
# describtion: This service starts|stops|restarts rsync server daemon.

. /etc/rc.d/init.d/functions

prog=$(basename $0)
lockfile=/var/lock/subsys/$prog

start() {
if [ -e $lockfile ]; then
action "Rsyncd is running already." /bin/false
else
touch $lockfile
action "Starting rsyncd finished." /bin/true

fi
}

stop() {
if [ -e $lockfile ]; then
rm -f $lockfile
action "Stopping rsyncd finished." /bin/true
else
action "Rsyncd is stopped already." /bin/false
fi
}

status() {
if [ -e $lockfile ]; then
echo "Rsyncd is running."
else
echo "Rsyncd is stopped."
fi
}

usage() {
echo "Usage:$prog {start|stop|status|restart}"
}

if [ $# -ne 1 ]; then
usage
exit
fi

case $1 in
start)
start
;;
stop)
stop
;;
status)
status
;;
restart)
stop
start
;;
*)
usage
;;
esac

题目6：打包备份；
如何实现对MySQL数据库进行分库加分表备份，请用脚本实现。

#!/bin/bash
yum install expect -y

DATE=`date +%Y-%m-%d`
OLD_DATE=`date +%Y-%m-%d -d '-30 days'`
BAK_DIR=/backup/mydata
DB_USER=root
DB_PASSWORD=cured
DB_name=DB_NAME
table_name=TABLE_NAME

[ -d ${BAK_DIR} ] || mkdir -p ${BAK_DIR}
[ -d ${BAK_DIR}/${DATE} ] || mkdir ${BAK_DIR}/${DATE}
[ ! -d ${BAK_DIR}/${OLD_DATE} ] || rm -rf ${BAK_DIR}/${OLD_DATE}

for DB_NAME in mysql $DB_NAME $TABLE_NAME
do
/usr/bin/mysqldump -u$DB_USER -p$DB_PASSWORD --databases ${DB_NAME} > ${BAK_DIR}/${DATE}/${DATE}-${DB_NAME}-backup.sql
/bin/sleep 3
done

cd ${BAK_DIR}
tar -cjf $DATE.db_bak.tar.bz2 $DATE
/bin/sleep 3

password='cured'
#System user's password for root@DB_BAK_SERVER
expect -c "
spawn scp $DATE.db_bak.tar.bz2 root@DB_BAK_SERVER:/backup/mydata
expect {
\"yes/no\" {set timeout 30; send \"yes\r\"; exp_continue;}
\"password\" {set timeout 30; send \"$password\r\";}
}
expect eof"
#####本脚本实现MySQL服务器打包压缩备份，并自动交互上传至备份服务器，分库分表备份暂未实现。#####

题目7：字符串打印；
使用for循环打印下面这句话中字母数不大于6的单词。
I am an interviewer, welcome to our company for interviewing .

#!/bin/bash

WORDS='I am an interviewer welcome to our company for interviewing'

for i in $WORDS; do
NUM= `echo $i | wc -L`
if [ $NUM -le 6 ]; then
echo $i
fi
done

for i in $WORDS; do
if [ ${#i} -le 6 ]; then
echo $i
fi
done

类似题目：字符串处理；
中启动力shell面试题：
1、按单词出现频率降序排序！
2、按字母出现频率降序排序！
the squid project provides a number of resources toassist users design,implement and support squid installations. Please browsethe documentation and support sections for more infomation

#!/bin/bash
WORDS='the squid project provides a number of resources toassist users design implement and support squid installations Please browsethe documentation and support sections for more infomation'

for i in $WORDS; do echo $i; done | sort | uniq -c | sort -rn

for i in $WORDS; do
for j in `seq 1 ${#i}`; do
ALPHA=`echo $i | cut -c$j`
echo $ALPHA
done
done | sort | uniq -c | sort -rn

题目8：判断数字大小；
开发shell脚本，分别实现以脚本传参以及read读入的方式比较2个整数大小。以屏幕输出的方式提醒用户比较结果。注意：一共是开发2个脚本。当用脚本传参以及read读入的方式需要对变量是否为数字、并且传参个数做判断。

#!/bin/bash
##########以脚本传参，非read读入方式（执行脚本时，在命令后面跟两个参数）##########

[ ! $# -ne 2 ] && {
echo "You should input 2 integer nums after run $0 next time,bye."
exit 1
}

expr $1 + 1 &> /dev/null
RETVAL_A=$?
expr $2 + 2 &> /dev/null
RETVAL_B=$?
[ $RETVAL_A -ne 0 -o $RETVAL_B -ne 0 ] && {
echo "At least one of numbers you input isn't integer num."
exit 2
}

if [ $1 -lt $2 ] ; then
echo "$1 < $2"
elif [ $1 -eq $2 ] ; then
echo "$1 = $2"
else
echo "$1 > $2"
fi

#!/bin/bash
##########read读入方式##########
read -t 10 -p "Please input one integer nums: " a
if [ -z $a ];then
echo "2B,Bye." && exit 1
fi

read -t 10 -p "Please input the other integer nums: " b
if [ -z $b ];then
echo "2B,Bye." && exit 1
fi

expr $a + 1 &> /dev/null
RETVAL_A=$?
expr $b + 2 &> /dev/null
RETVAL_B=$?
[ $RETVAL_A -ne 0 -o $RETVAL_B -ne 0 ] && {
echo "At least one of numbers you input isn't integer num."
exit 2
}

if [ $a -lt $b ] ; then
echo "$a < $b"
elif [ $a -eq $b ] ; then
echo "$a = $b"
else
echo "$a > $b"
fi

题目9：打印菜单；
打印选择菜单，一键安装web服务；
[root@node25 ~ ]# sh menu.sh
1.[install lamp]
2.[install lnmp]
3.[exit]
Please select an pition:

要求：
1、当用户输入1时，输出“start to install lamp.”然后执行/server/scripts/lamp.sh，脚本内容输出"lamp is installed"后退出脚本；
2、当用户输入2时，输出“start to install lnmp.”然后执行/server/scripts/lnmp.sh输出"lnmp is installed"后退出脚本;
3、当输入3时，退出当前菜单及脚本；
4、当输入任何其它字符，给出提示“Input error”后退出脚本；
5、要对执行的脚本进行相关条件判断，例如：脚本是否存在，是否可执行等。

#!/bin/bash

cat << EOF
1.[install lamp]
2.[install lnmp]
3.[exit]
============================
EOF

read -p "Please select an pition: " option
while [ "$option" != '1' -a "$option" != '2' -a "$option" != '3' ]; do
read -p "Wrong option, select again: " option
done

if [ "$option" == '1' ]; then
echo "Start to install lamp."
echo "Lamp is installed."
exit 1
elif [ "$option" == '2' ]; then
echo "Start to install lnmp."
echo "Lnmp is installed."
exit 2
else
echo "Exit"
exit 3
fi
#####最后的if多分支条件语句也可改为以下的case条件语句。#####
case $option in
1)
echo "Start to install lamp."
echo "Lamp is installed."
exit 1
;;
2)
echo "Start to install lnmp."
echo "Lnmp is installed."
exit 2
;;
3)
echo "Exit"
exit 3
;;
*)
echo "Usage:{1|2|3|}"
exit 4
;;
case

题目10：监控web和DB服务；
要求：1、分别监控web和DB服务是否正常，各不低于3种监控策略；2、间隔1分钟，持续监控。

监控web法二：http状态码，正常访问时为200；
yum install curl -y
curl -I -s -o /dev/null -w %{http_code} $WEB_SVR_URL
-I, --head Show document info only
-m, --max-time SECONDS
-o /dev/null, --output FILE to /dev/null
-s, --silent Silent mode
-w %{http_code},-w, --write-out FORMAT What to output after completion

yum install wget -y
wget -S -T 10 --spider $WEB_SVR_URL 2>&1 | grep "200" | awk '{print $2}'
-S, --server-response print server response.
--spider don't download anything.
-T, --timeout=SECONDS

监控web法三：web进程，这里以httpd为例；
ps -ef | grep httpd | grep -v grep | uniq | wc -l

#!/bin/bash

PORT_NUMS=`ss -tanl | grep :80 | uniq | wc -l`
#PORT_NUMS=`netstat -tanl | grep :80 | uniq | wc -l`
CONTACT='root@node77'
email_to_admin() {
mailsubject="Web Down."
mailbody="`date '+%F %H:%M:%S'`: Web service is unavailable,please check and repair."
echo $mailbody | mail -s "$mailsubject" $CONTACT
}

if [ $PORT_NUMS -eq 0 ]; then
echo "Web service is unavailable."
mail_to_admin
else
echo "Web service works correctly."
fi

#!/bin/bash
yum install curl wget -y
WEB_SVR_URL="http://192.168.0.76/index.html"
STATUS_CODE=`curl -I -s -o /dev/null -w %{http_code} $WEB_SVR_URL`
#STATUS_CODE=`wget -S -T 10 --spider $WEB_SVR_URL 2>&1 | grep "200" | awk '{print $2}'`
CONTACT='root@node77'
email_to_admin() {
mailsubject="Web Down."
mailbody="`date '+%F %H:%M:%S'`: Web service is unavailable,please check and repair."
echo $mailbody | mail -s "$mailsubject" $CONTACT
}

if [ $STATUS_CODE == "200" ]; then
echo "Web service works correctly."
else
echo "Web service is unavailable."
mail_to_admin
fi

#!/bin/bash
PID_NUMS=`ps -ef | grep httpd | grep -v grep | uniq | wc -l`
CONTACT='root@node77'
email_to_admin() {
mailsubject="Web Down."
mailbody="`date '+%F %H:%M:%S'`: Web service is unavailable,please check and repair."
echo $mailbody | mail -s "$mailsubject" $CONTACT
}

if [ $PID_NUMS -eq 0 ]; then
echo "Web service is unavailable."
mail_to_admin
else
echo "Web service works correctly."
fi

监控DB法一：监听端口（以MySQL或MariaDB为例）；
DB_PORT=`ss -tanl | grep :3306 | awk '{print $4}' | cut -d: -f2`
if [ $DB_PORT == "3306" ]; then
echo "Database service works correctly."
......

监控DB法二：sock文件（以MySQL或MariaDB为例）；
DB_HOME="/var/lib/mysql/"
DB_SOCK="mysql.sock"
SOCK_FILE=`ls -l $DB_HOME$DB_SOCK`

if [ -e $SOCK_FILE ]; then
echo "Database service works correctly."
......

题目11：监控memcache服务；
监控memcached服务是否正常，模拟用户（web客户端）检测；
使用nc命令加上set/get来模拟检测，以及监控响应时间及命中率。

#!/bin/bash
mem_srv=`ss -tunl | grep :11211 | wc -l`
log_path=/monitor/memcached
#email_of_admin=username@domain

if [ ! -d $log_path ]; then
mkdir -p $log_path
fi

if [ $mem_srv -gt 0 ]; then
printf "set test_key 0 3600 5\r\nhello\r\n" | nc 127.0.0.1 11211 &> /dev/null
retn_code_1=`echo $?`
printf "get test_key\r\n" | nc 127.0.0.1 11211 &> /dev/null
retn_code_2=`echo $?`
printf "delete test_key\r\n" | nc 127.0.0.1 11211 &> /dev/null
retn_code_3=`echo $?`

if [ $retn_code_1 -eq 0 -a $retn_code_2 -eq 0 -a $retn_code_3 -eq 0 ]; then
echo "Memcached service is OK."

num_of_get_hits=`printf "stats\r\n" | nc 127.0.0.1 11211 | grep "get_hits" | awk '{print $3}'`
num_of_cmd_get=`printf "stats\r\n" | nc 127.0.0.1 11211 | grep "cmd_get" | awk '{print $3}'`
get_hit_rate=`awk 'BEGIN{printf "%.2f%\n",('$num_of_get_hits'/'$num_of_cmd_get')*100}'`
echo "The get_hit_rate is : $get_hit_rate ."
fi

else
echo "Memcached service is down at `date +%F-%H:%M:%S`." | tee ${log_path}/error.log
# mail -s "Memcached service is down at `date +%F-%H:%M:%S`." $email_of_admin
fi

题目12：监控文件安全；
监控web文件是否被篡改，如果被篡改，则告警并且发邮件；每3分钟检查一次。

思路：Web上线后，使用md5sum命令对整个web目录中的所有文件生成相应地md5码，保存在/md5db/web/original.txt中。以后的md5码保存在/md5db/web/current.txt中，
被篡改的文件信息保存在/md5db/web/different.txt中。

#!/bin/bash
WEB_DIR="/var/www/html"
DATE=`date +%F`
TIME=`date +%H:%M:%S`
[ ! -d /md5db/web ] && mkdir -p /md5db/web
md5sum $WEB_DIR/* > /md5db/web/current.txt
diff /md5db/web/original.txt /md5db/web/current.txt > /md5db/web/different.txt
if [ ! $? -eq 0 ]; then
echo -e "\033[41;37m Warning!web files have been altered at $DATE $TIME.\033[0m"
cat /md5db/web/different.txt
# mail_to_amin
else
echo "Relax,web files are not be altered."
fi

crontab -e
*/20 * * * * root bash /bashs/md5db.sh

题目13：抓阄；
有N个学生，选3个参加实践；
要求：
1、执行脚本时，想去的同学输入姓名后，随机产生1-99之间的数字，数字最大的3人参加实践，已抓到的数字，下次不能再出现；
2、第一个名字输入后，屏幕输出信息，并将名字和数字记录到文件中，程序不能退出继续等待别的学生输入。

#!/bin/bash

NAME_LIST="/tmp/name_list.txt"
>$NAME_LIST
STU_NUMS=9

read_name(){
read -p "Please enter your name: " name
if [ -z $name ]; then
echo "Nothing input."
read_name
else
if [ `egrep -w "$name" $NAME_LIST | wc -l` -gt 0 ]; then
echo "This name is already in-use."
read_name
fi
if [ `egrep -w "$(echo $[$RANDOM%99+1])" $NAME_LIST | wc -l` -gt 0 ]; then
echo "This number is already in-use."
read_name
fi
if [ `egrep -w "$name" $NAME_LIST | wc -l` -eq 0 ] && [ `egrep -w "$(echo $[$RANDOM%99+1])" $NAME_LIST | wc -l` -eq 0 ]; then
echo "`echo $[$RANDOM%99+1]` $name" >> $NAME_LIST
fi
fi
}

while [ `cat $NAME_LIST | sort -rn -k1 | wc -l` -le $STU_NUMS ]; do
read_name
done

echo "The loting is ended, the results are as fallows: "
cat $NAME_LIST | sort -rn -k1 | head -3

#循环从0开始，这里表示学生数目的变量值为：学生总人数-1；
#随机产生1-99之间的数字，在使用RANDOM系统内置变量时需要用：数字最大值+1，如[$RANDOM%99+1]（也就是[$RANDOM%100]）。

题目14：检查网站地址是否正常；
https://www.aliyun.com
http://download.cirros-cloud.net
http://nginx.org
http://61.135.169.125
要求使用数组。

#!/bin/bash
declare -a urls
urls=(
"https://www.aliyun.com"
"http://download.cirros-cloud.net"
"http://nginx.org"
"http://61.135.169.125"
)

while true; do
for ((i=0;i<${#urls[*]};i++)); do
wget --spider --timeout=6 --tries=3 ${urls[$i]} &> /dev/null
if [ $? -eq 0 ]; then
echo "${urls[$i]} is OK."
else
echo "${urls[$i]} is down."
fi
sleep 3
done
done

题目15：暴力破解加密字符串；
已知下面的字符串是通过RANDOM随机数变量md5sum|cut -c 1-8截取后的结果，请破解这些字符串对应的md5sum前的RANDOM对应数字？
21029299
00205d1c
a3da1677
1f6d12dd

#!/bin/bash
rand_str=(
21029299
00205d1c
a3da1677
1f6d12dd
)

for ((i=0;i<32768;i++)); do
for ((j=0;j<${#rand_str[*]};j++)); do
if [ "`echo $i | md5sum | cut -c1-8`" == "${rand_str[$j]}" ]; then
echo $i ${rand_str[$j]}
fi
done
done

结果：
1346 00205d1c
7041 1f6d12dd
25345 a3da1677
25667 21029299

posted @ 2020-01-07 14:37 黄瓜不是好瓜阅读(635) 评论(0) 编辑收藏举报

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