dir1下有个log_1.log dir2下有个log_2.log 两个文件例如以下：
p_ylwu@VM_194_111_sles10_64:/home/jdxochen/exercise> cat -v dir1/log_1.log
1
3
5
7
9
0
p_ylwu@VM_194_111_sles10_64:/home/jdxochen/exercise> cat -v dir2/log_2.log
2
4
6
8
0
0
若想看具体的内容差别 使用diff -urNa dir1 dir2
參数说明：
-a Treat all files as text and compare themline-by-line, even if they do not seem to be text.
-N, --new-file
In directory comparison, if a file is found in
only one directory, treat it as present but empty
in the other directory.
-r When comparing directories, recursively compare
any subdirectories found.
-u Use the unified output format.