shell脚本，按字母出现频率降序排序。

[root@localhost oldboy]# cat file 
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
[root@localhost oldboy]# cat 97.sh 
 #!/bin/bash
cat file|
while read line
do
 for i in `seq 1 ${#line}`
 do
   a=`echo $line|cut -c $i`
   echo "$a" >> zimu.txt 
done
done

  cat zimu.txt|sed -r 's/[ 	]+//g'|grep -v ^$|sort|uniq -c |sort -nr 
[root@localhost oldboy]# bash 97.sh 
     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 P
      1 j
      1 g
      1 .
      1 ,
[root@localhost oldboy]# 

[root@localhost oldboy]# cat file|awk 'BEGIN{FS=""}{for(i=1;i<=NF;i++){if($i!=" "){a[$i]++}}}END{for(i in a){print i,a[i]}}'|sort -nr -k 2
s 19
e 17
o 16
t 14
n 12
i 12
r 11
a 9
u 8
p 7
d 7
m 6
l 4
c 4
f 3
q 2
h 2
b 2
w 1
v 1
P 1
j 1
g 1
. 1
, 1
[root@localhost oldboy]#