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

  cat zimu.txt|sed -r 's/[ \t]+//g'|grep -v ^$|sort|uniq -c |sort -nr
[root@localhost oldboy]# bash .sh
      s
      e
      o
      t
      n
      i
      r
       a
       u
       p
       d
       m
       l
       c
       f
       q
       h
       b
       w
       v
       P
       j
       g
       .
       ,
[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
s
e
o
t
n
i
r
a
u
p
d
m
l
c
f
q
h
b
w
v
P
j
g
.
,
[root@localhost oldboy]#