来源：老男孩博客 http://oldboy.blog.51cto.com/2561410/1632876
范例
企业面试题20(中企动力)：：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
第一问解答：
[root@LAMP ~]# echo "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
" > a.log
[root@LAMP ~]# cat a.log|tr " " "\n "|sort|uniq -c |sort -rn
2 support
2 squid
2 and
1 users
1 toassist
1 the
1 sections
1 resources
1 provides
1 project
1 of
1 number
1 more
1 installations.
1 infomation
1 for
1 documentation
1 design,implement
1 browsethe
1 a
1 Please
##############################################
第二问解答
[root@LAMP ~]# cat a.log |sed 's/./&\n/g'|sort|uniq -c|sort -rn
23
19 s
17 e
16 o
14 t
12 n
12 i
11 r
9 a
8 u
7 p
7 d
6 m
4 l
4 c
3 f
2 q
2 h
2 b
1 w
1 v
1 j
1 g
1 P
1 .
1 ,
1
[root@LAMP ~]
解答思路来源：
echo lvnianabcde | awk -F '' '{for(i=1;i<=NF;i++)print $i}'
echo lvnianabcde | sed 's/./&\n/g'
echo lvnianabcde | grep -Po '.'
echo lvnianabcde | grep -o '.'
echo lvnianabcde | fold -w1
###########################################################################
###########################################################################
###########################################################################
http://oldboy.blog.51cto.com/2561410/1687026
假如现在有个文本，格式如下：
a 1
b 3
c 2
d 7
b 5
a 3
g 2
f 6
d 9
即左边是随机字母，右边是随机数字，要求写个脚本使其输出格式为：
a 4
b 8
c 2
d 16
f 6
g 2
即将相同的字母后面的数字加在一起，按字母的顺序输出。
解答
[root@KEEP2 dd]# cat oldboy1.log
a 1
b 3
c 2
d 7
b 5
a 3
g 2
f 6
d 9
[root@KEEP2 dd]#
[root@KEEP2 dd]# cat oldboy1.log |awk '{a[$1]+=$2}END{for(i in a){print i,a[i]}}'
a 4
b 8
c 2
d 16
f 6
g 2
[root@KEEP2 dd]#
