uls(Uppercase Lowercase Shifting),用于将文本文件中的ASCII字符中的字母
进行大小写转换，共4种转换：
全转为大写；全转为小写；单词首字符大写；大小写互换（大写变小写，小写变大写）.如下为程序包内的README说明文件：
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What is uls
===========
uls is a text utility to translate between the uppercase and the lowercase of
ASCII text file.
How to make
===========
untar the source package and invoke 'make' in BASH to build this 'uls'.
e.g.
# make
# cp uls /usr/local/bin
Usage
===========
Usage: ./uls [-h] [-c<u2l|l2u|swap|cap>] <input.txt
where -h to print this help and exit.
-cu2l to switch all the uppercase to lowercase in the 'input.txt'.
-cl2u to switch all the lowercase to uppercase in the 'input.txt'.
-cswap to toggle between the uppercase and the lowercase in the 'input.txt'.
-ccap to make word Capitalized in the 'input.txt'.
Snapshots
=========
[root@ORA9 uls]# more input.txt
Read the source program and discover its structure.
Process this structure, e.g. to generate the target program.
[root@ORA9 uls]# ./uls -cl2u <input.txt
READ THE SOURCE PROGRAM AND DISCOVER ITS STRUCTURE.
PROCESS THIS STRUCTURE, E.G. TO GENERATE THE TARGET PROGRAM.
[root@ORA9 uls]# ./uls -ccap <input.txt
Read The Source Program And Discover Its Structure.
Process This Structure, E.G. To Generate The Target Program.
[root@ORA9 uls]# ./uls -cu2l <input.txt
read the source program and discover its structure.
process this structure, e.g. to generate the target program.
[root@ORA9 uls]# ./uls -cswap <input.txt
rEAD THE SOURCE PROGRAM AND DISCOVER ITS STRUCTURE.
pROCESS THIS STRUCTURE, E.G. TO GENERATE THE TARGET PROGRAM.
Report bugs
===========
Please send email to <snallie@tom.com>
===========
Ejoy fun!
snallie@tom.com
Tue Jan 5 13:44:54 CST 2016
