需求：从原日志中提供game_id, user_id, ip，并保证在game_id和user_id一至的情况下只保存一条记录。
$ cat a1.log
100029255 267006098 117.177.110.251
100029255 632432655 221.227.208.97
100031999 872069336 119.124.213.102
100031999 872069335 119.124.213.102
100031999 872069335 119.124.213.101
$ cat a2.log
100028337 558990503 60.180.229.137
100029249 365790727 211.161.29.213
100029249 602831481 117.156.5.54
100029255 1436504718 123.7.116.114
100029255 802209877 182.145.77.147
$ sort -u a2.log a1.log | wc -l
10
$ sort -u -k 1,2 a2.log a1.log | wc -l
9
$ sort -u -k 1,2 a2.log a1.log
100028337 558990503 60.180.229.137
100029249 365790727 211.161.29.213
100029249 602831481 117.156.5.54
100029255 1436504718 123.7.116.114
100029255 267006098 117.177.110.251
100029255 632432655 221.227.208.97
100029255 802209877 182.145.77.147
100031999 872069335 119.124.213.102
100031999 872069336 119.124.213.102