几道shell面试题及答案

企业面试题1：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？2102929900205d1ca3da16771f6d12dd890684b 解题思路：通过每次传递一个参数的方式，来实现依次破解 $RANDOM的范围为0-32767

#!/bin/bash
#Author: liuwei
#Site: www.51liuzw.com
for n in {0..32767}
do
MD5=`echo $n | md5sum | cut -c 1-8`
if [ "$MD5" == "$1" ];then
echo "$n is."
exit
else
echo "$n no."
fi
done

注：也可以通过定义数组的方法，来一次全部对比

#!/bin/bash
#Author: liuwei
#Site: www.51liuzw.com
array=(
00205d1c
21029299
a3da1677
1f6d12dd
890684b
)
for n in {0..32767}
do
MD5=`echo $n | md5sum | cut -c 1-8`
for i in ${array[@]};do
if [ "$MD5" == "$i" ];then
echo "$n and $i" >> c.log
break
else
echo "$n no."
fi
done
done

#cat c.log 1346 and 00205d1c
7041 and 1f6d12dd
25345 and a3da1677
25667 and 21029299

企业面试题2：批量检查多个网站地址是否正常 要求：shell数组方法实现，检测策略尽量模拟用户访问思路http://www.baidu.com http://www.taobao.com http://www.51liuzw.com http://192.168.50.199

#!/bin/bash
#Author: liuwei
#Site: www.51liuzw.com
array=( http://www.baidu.com http://www.taobao.com http://www.51liuzw.com http://192.168.50.199
)
for n in ${array[*]};do
URL=`curl -I -m 2 $n 2> /dev/null | egrep "200|302" | wc -l`
if [ "$URL" -eq 1 ];then
echo "$n is OK"
else
echo "$n is not OK"
fi
done

结果： #sh test.sh http://www.baidu.com is OK http://www.taobao.com is OK http://www.51liuzw.com is not OK http://192.168.50.199 is not OK

企业面试题3：：用shell处理以下内容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 1.按单词出现频率降序排序！ 解决思路：把空格换为换行符，并排序统计

#sed 's# #\n#g' c.txt | sort | uniq -c

2.按字母出现频率降序排序！ 解决思路：使用grep -o "\w"，把单词拆开并去除种各符号

#cat c.txt | grep -o "\w" | sort | uniq -c