名称：tr
### 1.比方说要把目录下所有的大写档名换为小写档名?
似乎有很多方式，"tr"是其中一种:
#!/bin/sh
dir="/tmp/testdir";
files=`find $dir -type f`;
for i in $files
do
dir_name=`dirname $i`;
ori_filename=`basename $i`
new_filename=`echo $ori_filename | tr [:upper:] [:lower:]` /dev/null;
#echo $new_filename;
mv $dir_name/$ori_filename $dir_name/$new_filename
done
### 2.自己试验中...lowercase to uppercase
tr abcdef...[del] ABCDE...[del]
tr a-z A-Z
tr '[:lower:]' '[:upper:]'
shell echo "this is a test" | tr a-z A-Z www
shell cat www
THIS IS A TEST
### 3.去掉不想要的字串
shell tr -d this ### 去掉有关 t.e.s.t
this
man
man
test
e
### 4.取代字串
shell tr -s "this" "TEST"
this
TEST
th
TE
