1.用uniq去除重复的行 $ cat happybirthday.txt
Happy Birthday to You! Happy Birthday to You! Happy Birthday Dear Tux! Happy Birthday to You!$ sort happybirthday.txt Happy Birthday Dear Tux! Happy Birthday to You! Happy Birthday to You! Happy Birthday to You! $ sort happybirthday.txt | uniq Happy Birthday Dear Tux! Happy Birthday to You! 2. $ sort happybirthday.txt | uniq -u Happy Birthday Dear Tux! $ sort happybirthday.txt | uniq -d Happy Birthday to You!