linux 中 sort n k u选项实现按照某一列对数据进行去重复

1、测试数据

root@DESKTOP-1N42TVH:/home/test2# ls
a.map
root@DESKTOP-1N42TVH:/home/test2# cat a.map   ##测试数据
1       s64199.1        0       55910
1       OAR19_64675012.1        0       85204
1       OAR19_64715327.1        0       122948
2       s47174.1        0       167127
2       s30876.1        0       176079
2       s16671.1        0       361433
3       s44996.1        0       144010
3       s26048.1        0       199910
3       OAR3_312122.1   0       234281
root@DESKTOP-1N42TVH:/home/test2# sort -k 1 -u a.map  ##-u没有起作用？？
1       OAR19_64675012.1        0       85204
1       OAR19_64715327.1        0       122948
1       s64199.1        0       55910
2       s16671.1        0       361433
2       s30876.1        0       176079
2       s47174.1        0       167127
3       OAR3_312122.1   0       234281
3       s26048.1        0       199910
3       s44996.1        0       144010
root@DESKTOP-1N42TVH:/home/test2# sort -n -k 1 -u a.map  ## -u只能在数值时才起作用？
1       s64199.1        0       55910
2       s47174.1        0       167127
3       s44996.1        0       144010