依据几列的值删除重复行

输入
1.txt
a 1 1
a 1 2
a b 3
a c 4
a c 5
a c 6
a d 7
a d 8
a e 9
a f 10
a f 11

输出
2.txt
a b 3
a e 9

先把1.txt按照指定的几列（第1,2列）排序
sort -k1,1 -k2,2  1.txt > 3.txt

awk '{last=$0; chr=$1;start=$2; getline; if( chr == $1 && start == $2 ) {print last"\t1";print $0"\t1";} else {print last"\t0";print $0"\t0";}}' 3.txt \
> 4.txt

awk 'BEGIN{getline;print $0"\t"0;}{last=$0; chr=$1;start=$2; getline; if( chr == $1 && start == $2 ) {print last"\t1";print $0"\t1";} else {print last"\t0";print $0"\t0";}}' 4.txt \
> 5.txt

awk '$4 == 0 && $5 == 0'  5.txt | awk '{print $1"\t"$2"\t"$3;}' > 2.txt