uniq命令的作用：显示唯一的行，对于那些连续重复的行只显示一次！
接下来通过实践实例说明：
[root@stu100 ~]# cat test
boy took bat home
boy took bat home
girl took bat home
dog brought hat home
dog brought hat home
dog brought hat home
看test文件的内容，可以看到其中的连续重复行
[root@stu100 ~]# uniq test
boy took bat home
girl took bat home
dog brought hat home
uniq命令不加任何参数，仅显示连续重复的行一次
[root@stu100 ~]# uniq -c test
2 boy took bat home
1 girl took bat home
3 dog brought hat home
-c 参数显示文件中每行连续出现的次数。
[root@stu100 ~]# uniq -d test
boy took bat home
dog brought hat home
-d选项仅显示文件中连续重复出现的行。
[root@stu100 ~]# uniq -u test
girl took bat home
-u选项显示文件中没有连续出现的行。
[root@stu100 ~]# uniq -f 2 -s 2 test
boy took bat home
忽略每行的前2个字段，忽略第二个空白字符和第三个字段的首字符，结果at home
[root@stu100 ~]# uniq -f 1 test
boy took bat home
dog brought hat home
忽略每行的第一个字段，这样boy ，girl开头的行看起来是连续重复的行。