uniq命令：
uniq [OPTION]... [FILE]...
-c: 显示每行重复出现的次数；
[root@ansible ~]# cat test.txt
this is test
this is test
this is your list
this is this
[root@ansible ~]# uniq -c test.txt
2 this is test
1 this is your list
1 this is this
-d: 仅显示重复过的行；
[root@ansible ~]# cat test.txt
this is test
this is test
this is your list
this is this
[root@ansible ~]# uniq -d test.txt
this is test
-u: 仅显示不曾重复的行；
[root@ansible ~]# cat test.txt
this is test
this is test
this is your list
this is this
[root@ansible ~]# uniq -u test.txt
this is your list
this is this
