企业shell面试题及解答

1、面试题：使用for循环在/tmp目录下批量创建10个html文件，其中每个文件需要包含10个随机小写字母加固定字符串template，示例如下

aaesdffbnv_template.html

方法1：

cd /tmp
for ((i=;i<;i++));do touch `echo $RANDOM | md5sum | sed 's/[^a-z]//g' | cut -c -`_template.html;done

方法2：

cd /tmp

for i in `seq `;do touch `openssl rand -base64  | sed 's/[^a-z]//g' | cut -c -`_template.html;done

2、面试题：批量改名 将以上所得的文件名中的template全部改成leon，并且将html改成大写

方法1：

rename template.html leon.HTML *.html

方法2：

ls *.html | awk -F '_' '{print "mv "$0" "$1"_leon.HTML"}' | bash

3、面试题：批量10个系统账号template01到template10并设置密码（密码为随机数）

方法1：

for i in `seq -w 01 10`;do useradd -M template$i;echo $RANDOM |md5sum  | cut -c 1-10 | tee -a passwd.log | template$i;done

方法2：

echo template{..} | tr " " "\n" | sed -r 's#(.*)#useradd \1;pass=`echo $RANDOM | md5sum | cut -c 1-10`;echo "$pass"|passwd --stdin \1;echo -e "\1\t`echo "$pass"`" >> /tmp/passwd.log#g' | bash

方法3：

echo template{..} | xargs -n1 useradd;echo template{..}:`cat /dev/urandom|tr -dc -|fold -w8|head -1` | xargs -n1|tee -a pass.txt|chpasswd

4、面试题：写一个脚本，判断192.168.8.0/24网路里，当前在线的IP有哪些

方法1：

#!/bin/bash                                                                                                                         G

for i in `seq `

do

    {

    ping -c  -W  192.168..$i &>/dev/null

    if [ $? -eq  ];then

        echo "192.168.8.$i is alive"                                                                                                ?

    fi                                                                                                                              ?

}&                     #shell的并发检测功能，批量ping，快速返回结果

done 

方法2：使用namp（需要安装namp）

nmap -sP 192.168.8.0/ | awk '/Nmap scan report for/{print $NF}'    #1到2秒返回结果

5、面试题：写一个shell脚本以解决DDOS攻击生产的问题

请根据Web日志或网络连接数，监控当某个IP并发连接数或短时间内PV达到100时，即调用防火墙命令封掉该对应的IP：防火墙的命令为：

iptables -I INPUT -s IP -j DROP

参考此脚本：

#!/bin/bash

#Author Template

#Time -- :

file=$

log_file=/tmp/tmp.log

JudgeExt(){

    if expr "$1" : ".*\.log" &> /dev/null;then

        :

    else

        echo "Usage: $0 xxx.log"

        exit

    fi

}

IpCount(){

    grep "ESTABLISHED" $ | gawk -F "[ :]+" '{++S[$(NF-3)]} END {for (key in S) print S[key],key}' | sort -rn -k1 | head - > $log_file

}

ipt(){

    local ip=$

    if [ `iptabls -L -n | grep "$ip" | wc -l` -lt  ];then

        iptabls -I INPUT -s $ip -j DROP

        echo "$line  is dorpped" >> /tmp/drop_list_$(date +%F).log

    fi

}

main(){

    JudgeExt $file

    while true

    do

        IpCount $file

        while read line

        do

            ip=`echo $line | gawk '{print $2}'`

            count=`echo $line | gawk '{print $1}'`

            if [ $count -gt  ];then

                ipt $ip

            fi

        done < $log_file

        sleep

    done

}

main

6、面试题：请用脚本实现Mysql数据库分库备份

#!/bin/bash

echo -e [`date +"%Y-%m-%d %H:%M:%S"`] start

#system time

time=`date +"%y-%m-%d"`

#host IP

host="127.0.0.1"

#database backup user

user="root"

#database password

passwd="yourpasswd"

#Create a backup directory

mkdir -p /backup/db/"$time"

#list database name

all_database=`/usr/bin/mysql -u$user -p$passwd -Bse 'show databases'`

#in the table from the database backup

for i in $all_database

do

/usr/bin/mysqldump -u$user -p$passwd $i > /backup/db/"$time"/"$i"_"$time".sql

done

echo -e [`date +"%Y-%m-%d %H:%M:%S"`]  end

exit 

7、面试题：请用脚本实现Mysql数据库分库分表备份

#!/bin/bash

PATH="/application/mysql/bin:$PATH"

DBPATH=/server/backup

MYUSER=root

MYPASS=

SOCKET=/data//mysql.sock

MYCMD="mysql -u$MYUSER -p$MYPASS -S $SOCKET"

MYDUMP="mysqldump -u$MYUSER -p$MYPASS -S $SOCKET"

[ ! -d "$DBPATH" ] && mkdir $DBPATH

for dbname in `$MYCMD -e "show database;" | sed '1,2d' | egrep -v "mysql|schema"`

do

    mkdir $DBPATH/${dbname}_$(date +%F) -p

    for table in `$MYCMD -e "show tables from $dbname;"| sed '1d'`

    do

        $MYDUMP $dbname $table | gzip > $DBPATH/${dbname}_$(date +%F)/${dbname}_${table}.sql.gz

    done

done

8、面试题：请开发一个shell脚本，比较两个整数的大小，通过传参的方式

#!/bin/bash

a=$

b=$

Usage(){

echo "Usage:$0 NUM1 NUM2"

exit

}

[ $# -ne  ] && { ##判断传参个数

Usage

}

expr $a +  &> /dev/null #使用expr只能计算两个整数的原理，判断传入的参数是否为整数

RETVAL_A=$?

expr $b +  &> /dev/null

RETVAL_B=$?

[ $RETVAL_A -ne  -o $RETVAL_B -ne  ] && {

echo "you must input integer "

exit

}

if [ "$a" -lt "$b" ];then

echo "$a < $b"

elif [ "$a" -gt "$b" ];then

echo "$a > $b"

else

echo "$a = $b"

fi

exit 

9、面试题：打印选择菜单，按照选择一键安装不同的web服务

#!/bin/bash

PS3="Enter option: "                #设置提示符

stty erase ^h                           #设置退格删除键为backspace

trap "echo Goodbye..." EXIT     #检测到exit信号，输出Goodbye

select option in "install LNMP" "install LANP" "Exit"

do

    case $option in

        "install LNMP")

            sh install_lnmp.sh

            ;;

        "install LANP")

            sh install_lamp.sh

            ;;

        "Exit")

            exit

            ;;

        *)

            echo ""

            ;;

        esac

done                        

10、Web及Mysql服务异常监测

网站监测：

#!/bin/bash

#Author Template

#Time -- :

url_list=(

http://www.cnblogs.com/Template/

http://www.baidu.com

http://127.0.0.1

)

. /etc/init.d/functions

function wait(){

    echo -n "3 秒后执行检查."

    for ((i=;i<;i++))

    do

        echo -n "." ;sleep

    done

    echo

}

function check_url(){

    wait

    for ((i=;i<`echo ${#url_list[*]}`;i++))

    do

        wget -o /dev/null -T  --tries= --spider ${url_list[$i]} &> /dev/null

        if [ $? -eq  ];then

            action "${url_list[$i]}" /bin/true

        else

            action "${url_list[$i]}" /bin/false

        fi

        ((check_count++))

    done

    }

main(){

    while true

    do

        check_url

        echo "------------check count:${check_count}------------------"

        sleep

    done

}

main

Mysql监测：

方法1：

#!/bin/bash

if [ "`netstat -tlunp  | grep 3306 | awk -F "[ :]+" '{print $4}'`" = "" ];then

    echo "Mysql is Running"

else

    echo "Mysql is Stopped"

    /etc/init.d/mysqld start

fi

方法2：

#!/bin/bash

if [ `netstat -tlunp | grep "" | wc -l`  -gt  ];then

    echo "Mysql is Running"

else

    echo "Mysql is Stopped"

    /etc/init.d/mysqld start

fi

方法3：

#!/bin/bash

if [ `lsof -i tcp: | wc -l`  -gt  ];then

    echo "Mysql is Running"

else

    echo "Mysql is Stopped"

    /etc/init.d/mysqld start

fi

11、面试题：写出网络服务独立进程模式下Rsync的系统启动脚本，例如：/etc/init.d/rsyncd {start|stop|restart}

#!/bin/bash

# chkconfig:

#description Rsyncd start stop script

. /etc/init.d/functions

function Usage(){

    echo "Usage:$0 {start | stop | restart}"

    exit

}

function start (){

    rsync --daemon

    sleep

    if [ `netstat -tlunp | grep rsync | wc -l` -ge  ];then

        action "rsyncd  started" /bin/true

    else

        action "rsyncd started" /bin/false

        exit

    fi

}

function stop(){

    killall rsync &> /dev/null

    sleep

    if [ `netstat -tlunp | grep rsync|wc -l` -eq  ];then

        action "rsyncd stopped" /bin/true

    else

        action "rsyncd stopped" /bin/false

        exit

    fi

}

function restart(){

    stop && start

}

case "$1" in

    "start")

            start

            ;;

    "stop")

            stop

            ;;

    "restart")

            restart

            ;;

        *)

            Usage

esac

12、面试题：请写出mysql多实例启动脚本

#!/bin/bash

port=

mysql_user="root"

mysql_pwd=""

CmdPath="/application/mysql/bin"

mysql_sock="/data/${port}/mysql.sock"

. /etc/init.d/functions

start(){

    if [ ! -e "$mysql_sock" ];then

         printf "Starting MySQL...\n"

        /bin/sh ${CmdPath}/mysqld_safe --defaults-file=/data/${port}/my.cnf >& > /dev/null &

    [ $? -eq  ] && action "Mysql start" /bin/true || action "Mysql start" /bin/false

    else

        printf "MySQL is running...\n"

        exit

    fi

}

stop(){

    if [ ! -e "$mysql_sock" ];then

        printf "MySQL is stopped...\n"

        exit

    else

        printf "Stoping MySQL...\n"

        ${CmdPath}/mysqladmin -u ${mysql_user} -p${mysql_pwd} -S /data/${port}/mysql.sock shutdown

    [ $? -eq  ] && action "Stop mysql" /bin/true || action "Stop mysql" /bin/false

    fi

}

restart(){

    printf "Restarting MySQL...\n"

    stop

    sleep

    start

}

Usage(){

    echo "Usage: /data/${port}/mysql (start|stop|restart)"

    exit

}

case "$1" in

start)

    start

    ;;

stop)

    stop

    ;;

restart)

    restart

    ;;

*)

    Usage

    ;;

esac