测试数据：
[xiluhua@vm-xiluhua][~]$ cat msn.txt
aaa bbb
bbb ccc
ccc ddd
bbb eee
aaa ccc
bbb sss [xiluhua@vm-xiluhua][~]$ cat msn.bk
aaa bbb
BBB CCC
CCC DDD
BBB EEE
AAA CCC
BBB SSS
-y选项，并排的格式比较文件msn.txt和msn.bk
-w选项，忽略空格
中间有竖线表示两边不一致
[xiluhua@vm-xiluhua][~]$ diff -yw msn.txt msn.bk
aaa bbb aaa bbb
bbb ccc | BBB CCC
ccc ddd | CCC DDD
bbb eee | BBB EEE
aaa ccc | AAA CCC
bbb sss | BBB SSS
-c选项，上下的格式比较文件msn.txt和msn.bk
[xiluhua@vm-xiluhua][~]$ diff -cw msn.txt msn.bk
*** msn.txt 2016-07-15 21:00:19.300146161 +0800
--- msn.bk 2016-07-16 15:01:47.385298935 +0800
***************
*** 1,6 ****
aaa bbb
! bbb ccc
! ccc ddd
! bbb eee
! aaa ccc
! bbb sss
--- 1,6 ----
aaa bbb
! BBB CCC
! CCC DDD
! BBB EEE
! AAA CCC
! BBB SSS