[root@bogon 桌面]# cat booklist.txt

9787302115199

9787302142201

9787302115199

9787115242907

9787115253293

9787302115199

9787302142201

9787115253293

[root@bogon 桌面]# sort booklist.txt | uniq -c | awk '$1>=2 {print $0}'

      2 9787115253293

      3 9787302115199

      2 9787302142201

[root@bogon 桌面]# sort booklist.txt | uniq -c | awk '$1>=2 {print $0}' >booklist-multi.txt