工作中常用的awk命令

http://man.linuxde.net/awk

1.为一列id加逗号

awk 'BEGIN {ORS=","}{print $1}' test.txt

2.统计一列id中重复的id

awk '{a[$1]++} END{for(i in a){if(a[i]>1){print i}}}' test.txt