【面试题】Shell脚本企业面试

企业面试题：

1.批量生产随机字符文件名

使用for循环在/oldboy目录下批量创建10个html文件，期中每个文件需要包含10个随机小写字母加固定字符串oldboy：

#!/bin/bash

p=/oldboy

[ -d $p ] || mkdir $p

for a in {1..10}

do

n=`openssl rand -base64 40|sed 's#[^a-z]##g'|cut -c 2-11`

touch $p/oldboy_${n}.html

done

======================================================================================

2.批量改名

将上题所得文件名中的oldboy字符串全部改成oldgirl,并且将扩展名html全部改成大写HTML（不低于2 种方法）

#!/bin/bash

a=/oldboy

cd $a

for n in `ls /oldboy|sed -r 's#oldboy_(.*).html#\1#g'`

do

#b=`ls /oldboy|sed -r 's#oldboy_(.*).html#\1#g'`

mv oldboy_${n}.html oldgirl_${n}.HTML

done

#!/bin/bash

a=/oldboy

cd $a

for n in `ls /oldboy|awk -F "[_.]" '{print $2}'`

do

#b=`ls /oldboy|awk -F "[_.]" '{print $2}'`

mv oldboy_${n}.html oldgirl_${n}.HTML

done

=======================================================================================

3.批量创建特殊要求用户案例

批量创建10 个系统帐号oldboy01-oldboy10并设置密码（密码为随机8位数）。不用for 循环的实现思路：

#!/bin/bash

mima=/tmp/mima.log

for n in oldboy{01..10}

do

useradd $n &>/dev/null

a=`openssl rand -base64 40|sed 's#[^a-z]##g'|cut -c 2-9`

echo "$a"|passwd --stdin $n &>/dev/null

echo -e "$n:$a" >>$mima

done

=======================================================================================

4.扫描网络内存活主机

写一个shell脚本，判断10.0.0.0/24网络里，当前在线的Ip有哪些

#!/bin/bash

for n in 10.0.0.{1..253}

do

{

ping -W 2 -c 2 ${n} &>/dev/ull

if [ $? -eq 0 ]

then

echo "$n is ok"

fi

}&

done

sleep 2

=======================================================================================

5.解决DOS攻击

写一个Shell脚本解决DOS攻击生产案例。请根据 web 日志，监控当某个 IP 短时内 PV 达到 100（读者根据实际情况设定），即调用防火墙命令封掉对应的IP。防火墙命令为：iptables -I INPUT -s IP -j DROP（IP为要封的地址）

#!/bin/bash

file=$1

awk '{print $1}' $1|grep -v "^$"|sort|uniq -c >/tmp/ip.log

exec
while read line

do

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

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

if [ $count -ge 30 ] && [ `iptables -L -n|grep $ip|wc -l` -lt 1 ]

then

iptables -I INPUT -s $ip -j DROP

echo "$ip 已干掉"

else

fi

done

=======================================================================================

6.MySQl数据库分库备份

请用脚本实现对MySQL数据库分库备份

#!/bin/bash

my=`mysql -uroot -poldboy123 -e 2>/dev/null "show databases;"|sed 1d|egrep -v "_schema"`

for n in $my

do

mysqldump -uroot -poldboy123 2>/dev/null -B $n |gzip >/tmp/${n}.sql.gz

done

=======================================================================================

7.MySQl数据库分库分表备份

请用脚本实现对MySQL数据库分库分表备份

#!/bin/bash

for dbname in `mysql -e "show databases;"|sed 1d|egrep -v "_schema"`;

do

for tablename in `mysql -e "show tables from $dbname;"|sed 1d`

do

mysqldump --lock-tables=0 $dbname $tablename|gzip >/tmp/${dbname}_${tablename}_$(date +%F).sql.gz;

done

done

=======================================================================================

8. 利用 bash for 循环打印下面这句话中字母数不大于 6 的单词（某企业面试真

题）。 I am oldboy teacher welcome to oldboy training class

#!/bin/bash

for n in I am oldboy teacher welcome to oldboy training class

do

if [ `echo $n|wc -L` -le 6 ]

then

echo $n

fi

done

=======================================================================================

9.已知下面的字符串是通过将RANDOM随机数

采用md5sum加密后任意取出连续10位的结果，

请破解这些字符串对应的md5sum前的数字？

4fe8bf20ed

#!/bin/bash

for n in {0..32767}

do

echo -n "$n " >>/tmp/md5sum.txt

echo $n|md5sum >>/tmp/md5sum.txt

done

grep "4fe8bf20ed" /tmp/md5sum.txt

=======================================================================================

10.使用 read 读入方式比较两个整数大小，要求对用户输入的内容严格判断是否

为整数，是否输入了两个数字。

#!/bin/bash

read -p "请比较两个数大小:" a b

expr $a + $b + 999 &>/dev/null

if [ $? -ne 0 ]

then

echo "输入两整数啊你输入的是嘛"

exit 1

elif [ $a -gt $b ]

then

echo "$a>$b"

exit 0

elif [ $a -lt $b ]

then

echo "$a<$b"

exit 0

else [ $a -eq $b ]

echo "$a=$b"

exit 0

fi

=======================================================================================

11.菜单自动化软件部署经典案例

综合实例：打印选择菜单，按照选择一键安装不同的Web服务。示例菜单：

[root@oldboy scripts]# sh menu.sh

1.[install lamp]

2.[install lnmp]

3.[exit]

pls input the num you want: 要求： 1、当用户输入1 时，输出“start installing lamp.提示”然后执行/server/scripts/lamp.sh，脚本内容输出"lamp is installed"后退出脚本，工作中就是正式lamp一键安装脚本； 2、当用户输入2时，输出“start installing lnmp.提示” 然后执行/server/scripts/lnmp.sh 输出"lnmp is installed"后退出脚本，工作中就是正式lnmp一键安装脚本； 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的条件判断，例如：脚本文件是否存在，是否可执行等判断，尽量用上前面讲解的知识点。

#!/bin/bash

cat<
========================

1.[install lamp]

2.[install lnmp]

3.[exit]

========================

EOF

read -p "pls input the num you want:" a

expr $a + 999 &>/dev/null

if [ $? -ne 0 ]

then

echo "pls input the num you want:{1|2|3}"

exit 1

fi

if [ $a -eq 1 ]

then

touch /server/scripts/lamp.sh

echo 'echo "lamp is installed"' >/server/scripts/lamp.sh

source /server/scripts/lamp.sh

exit 1

elif [ $a -eq 2 ]

then

echo 'echo "lnmp is installed"' >/server/scripts/lamp.sh

source /server/scripts/lamp.sh

exit 1

elif [ $a -eq 3 ]

then

echo "已退出"

fi

=======================================================================================12.MySQl服务器异常监测

用if条件语句实现对MySQL数据库是否正常的检查，如果服务未启动，则启动相应服务。

#1/bin/bash

if [ `netstat -lntup|grep mysqld|wc -l` -ge 1 ]

then

echo "mysql服务已开启"

else [ `netstat -lntup|grep mysqld|wc -l` -eq 0 ]

echo "mysql服务没开" | tee /tmp/mysql_jinc.log

systemctl start mysqld

fi

=======================================================================================

13.开发Rsync服务启动脚本

#!/bin/bash

. /etc/init.d/functions

function usage(){

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

exit 0

}

function start(){

rsync --daemon

sleep 2

if [ `netstat -lntup|grep rsync|wc -l` -ge 1 ]

then

action "rsyncd is started." /bin/true

else

action "rsyncd is started." /bin/false

fi

}

function stop(){

killall rsync &>/dev/null

sleep 2

if [ `netstat -lntup|grep rsync|wc -l` -eq 0 ]

then

action "rsyncd is stopped." /bin/true

else

action "rsyncd is stopped." /bin/false

fi

}

function main(){

if [ $# -ne 1 ]

then

usage

fi

if [ "$1" = "start" ]

then

start

elif [ "$1" = "stop" ]

then

stop

elif [ "$1" = "restart" ]

then

stop

sleep 2

start

else

usage

fi

}

main $*

=======================================================================================

14.开发MySQL启动脚本

#!/bin/bash

. /etc/init.d/functions

function usage(){

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

exit 0

}

function start(){

systemctl start mysqld

sleep 2

if [ `netstat -lntup|grep mysqld|wc -l` -ge 1 ]

then

action "mysqld is started." /bin/true

else

action "mysqld is started." /bin/false

fi

}

function stop(){

systemctl stop mysqld

sleep 2

if [ `netstat -lntup|grep mysqld|wc -l` -eq 0 ]

then

action "mysqld is stopped." /bin/true

else

action "mysqld is stopped." /bin/false

fi

}

function main(){

if [ $# -ne 1 ]

then

usage

fi

if [ "$1" = "start" ]

then

start

elif [ "$1" = "stop" ]

then

stop

elif [ "$1" = "restart" ]

then

stop

sleep 2

start

else

usage

fi

}

main $*

=======================================================================================

15.破解RANDOM随机数

已知下面字符串是RANDOM随机数变量经过md5sum处理后，在截取一部分连续字符串的结果，请破解这些字符串在使用md5sun处理前所未有的数字

21029299

00205d1c

a3da1677

1f6d12dd

890684b

#!/bin/sh

array=( #<==把待比较的字符串信息放到数组里。

21029299

00205d1c

a3da1677

1f6d12dd

890684b

)

Path=/tmp/md5.txt

funGetMd5() {

> $Path

for ((Num=0;Num<=32767;Num++))

do

{

Stat=$(echo $Num|md5sum)

echo "$Stat $Num" >> $Path #<==建立数字和md5sum后的内容对应关系。

}&

done

}

funFindMd5() {

word=$(echo "${array[@]}"|sed -r 's# |\n#|#g') #<==取出所有数组元素并用|分隔开。

grep --color=auto -E "$word" $Path #<==同时过滤包含所有不同字符串的内容。

}

funcMain(){

funGetMd5

funFindMd5

}

funcMain

===========================================================================================================

16.批量检查多个网站地址是否正常

企业面试题：批量检查多个网站地址是否正常

要求：

1、使用shell数组方法实现，检测策略尽量模拟用户访问。

2、每 10秒钟做一次所有的检测，无法访问的输出报警。

3、待检测的地址如下

http://blog.oldboyedu.com

http://www.baidu.com

http://oldboy.blog.51cto.com

http://10.0.0.7

#!/bin/bash

. /etc/init.d/functions

ch=0

url=(

http://blog.oldboyedu.com

http://www.baidu.com

http://oldboy.blog.51cto.com

http://10.0.0.7

)

function wait(){

echo -n '3秒后，执行检查URL操作'

for ((i=0;i<3;i++))

do

echo -n "."

sleep 1

done

echo

}

function ch_url(){

wait

for usr in ${url[*]}

do

wget -q -o /dev/null -T 13 --tries=2 --spider $usr &>/dev/null

if [ $? -eq 0 ]

then

action "$usr" /bin/true

else

action "$usr" /bin/false

fi

done

((ch++))

}

main(){

while true

do

ch_url

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

sleep 10

done

}

main

===========================================================================================================

17.单词及字母去重排序案例

用shell处理以下内容 1、按单词出现频率降序排序（不低于3种方法） 2、按字母出现频率降序排序（不低于3种方法）

the squid project provides a number of resources to assist users design,implement and support squid installations. Please browse the documentation and support sections for more infomation,by oldboy training.

方法1：

#!/bin/bash

px="the squid project provides a number of resources to assist users design,implement and support squid installations. Please browse the documentation and support sections for more infomation,by oldboy training."

zimu(){

for n in `echo $px|sed -e 's#[^0-Z ]##g'`

do

for ((i=0;i<${#n};i++))

do

echo ${n:i:1}

done

done

}

danci(){

for n in `echo $px|sed 's#[^0-Z ]##g'`

do

echo $n

done

}

main(){

danci|sort|uniq -c|sort -n -r

echo ======================

zimu|sort|uniq -c|sort -n -r

}

main

其他方法

创建个文件xxx把the squid project provides a number of resources to assist users design,implement and support squid installations. Please browse the documentation and support sections for more infomation,by oldboy training. 加进去

tr ",. " "\n"

awk -F"[,. ]+" '{for(i=1;i<=NF;i++) S[$i]++}END{for(k in S) print S[k],k}' 17.txt|sort -nr

sed 's# #\n#g;s#,#\n#g' danci.txt |sort |uniq -c|sort -nr

sed 's# #\n#g;s#,#\n#g' danci.txt |awk '{S[$1]++}END{for(k in S) print S[k],k}'|sort -nr

===========================================================================================================

18.通过脚本传参的方式，检查Web网站URL是否正常（要求主体使用函数）。

#!/bin/bash

. /etc/init.d/functions

check_url(){

wget -q -o /dev/null -T 2 --tries=1 --spider $1

if [ $? -eq 0 ]

then

action "$1 is ok" /bin/true

else

action "$1 is no" /bin/false

fi

}

usage(){

echo "Usage: $0 url"

}

main(){

if [ $# -ne 1 ]

then

usage

else

check_url $1

fi

}

main $*

[root@web02 /server/scripts/kaoshi]# sh 5.sh www.baidu.com

www.baidu.com is ok [ 确定 ]

===========================================================================================================

19.猜数字游戏。首先让系统随机生成一个数字，给这个数字定一个范围（1-60），

让用户输入猜的数字，对输入进行判断，如果不符合要求，就给予高或低的提示，猜对后则

给出猜对用的次数。

#!/bin/bash

toutal=0

num=$((RANDOM%61))

echo "数字结果是$num"

echo "=========================="

usleep 100000

clear

cat<
=====================

| 猜猜0~60的数字 |

=====================

EOF

epple(){

read -p "请输入你猜的数字:" pa

expr $pa + 1 &>/dev/null

if [ $# -eq 0 ]

then

echo "别逗我了，快猜数字"

exit

fi

}

apple(){

read -p "请输入你猜的数字:" price

expr $price + 1 &>/dev/null

if [ $? -ne 0 ]

then

echo "别逗我了，快猜数字"

apple

fi

}

guess(){

((total++))

if [ $price -eq $num ]

then

echo "猜对了就是$num"

if [ $total -le 3 ]

then

echo "一共猜了$total次,厉害啊年轻人。"

elif [ $total -gt 3 -a $total -le 6 ]

then

echo "一共猜了$total次,猜了这么多次,不行啊"

elif [ $total -gt 6 ]

then

echo "一共猜了$total次,猜了这么多次,真废物"

fi

exit 0

elif [ $price -gt $num ]

then

echo "哈哈,没有这么大"

echo "再给你一次机会,请继续猜:"

apple

elif [ $price -lt $num ]

then

echo "太小了，太小了"

echo "再给你一次机会,请继续猜:"

apple

fi

}

main(){

apple

while true

do

guess

done

}

main

===========================================================================================================

20.计算从1 加到100之和（要求用for 和while，至少给出两种方法）。

方法一：

[root@web02 /server/scripts/kaoshi]# cat 8.sh

sum=0

i=1

for i in `seq 1 100`

sum=$(($sum+i))

i=$(($i+1))

done

echo $sum

方法二：

#!/bin/bash

sum=0

for ((n=0;n<=100;n++))

((sum=sum+n))

done

echo $sum

方法三：

#!/bin/bash

sum=0

for n in `seq 1 100`

sum=$[$sum+$n]

done

echo $sum

方法四：

#!/bin/bash

i=0

n=1

while [ $n -lt 101 ]

i=$[$n+$i]

n=$[$n+1]

done

echo $i

===========================================================================================================

21.已知：/etc/hosts的内容为

192.168.1.11 oldboy11

192.168.1.21 oldboy21

192.168.1.31 oldboy31

请用shell脚本实现，怎么才能在输入IP后找到/etc/hosts里对应的唯一的hostname? 解答：

#!/bin/bash

cat>> /etc/hosts <
192.168.1.11 oldboy11

192.168.1.21 oldboy21

192.168.1.31 oldboy31

EOF

if [ $# -ne 1 ]

then

echo "Usage: $0 + IP"

exit 1

fi

read -p "在输入IP后找到/etc/hosts里对应的唯一的hostname:" a

if [ $a == "192.168.1.11" ]

then

echo oldboy11

elif [ $a == "192.168.1.21" ]

then

echo oldboy21

elif [ $a == "192.168.1.31" ]

then

echo oldboy31

fi

===========================================================================================================

22.请教一个问题

at oldboy.txt

192.168.1.1 /hello1/b.do?bb=4

192.168.1.2 /hello2/a.do?ha=3

192.168.1.3 /hello3/r.do?ha=4

如何显示成以下效果

192.168.1.1 b.do

192.168.1.2 a.do

192.168.1.3 r.do

方法一：最简单的方法是

#!/bin/bash

cat> oldboy.txt<

192.168.1.1 /hello1/b.do?bb=4

192.168.1.2 /hello2/a.do?ha=3

192.168.1.3 /hello3/r.do?ha=4

EOF

cat oldboy.txt| awk -F "[/?]+" '{print $1 $3}'

方法2：

#!/bin/bash

array=(

"192.168.1.1 /hello1/b.do?bb=4"

"192.168.1.2 /hello2/a.do?ha=3"

"192.168.1.3 /hello3/r.do?ha=4"

)

for n in "${array[@]}"

echo $n|awk -F "[ /?]" '{print $1,$4}'

done

while read line

echo $line|awk -F "[ /?]" '{print $1,$4}'

done

===========================================================================================================

【面试题】Shell脚本企业面试

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