awk的split问题请教

chaogooler8888

[root@gimei-test ~]# echo "[20:37:04]180" | awk -F'[]:[]' '{print ($2*3600+$3*60+$4)*1000+$5}'
74224180
[root@gimei-test ~]# echo "[20:37:04]180"|awk '{ split($0,a,"[]:[]");totalms=(a[2]*3600+a[3]*60+a[4]) * 1000+a[5];print totalms;}'
74224180
[root@gimei-test ~]# echo "[20:37:04]180" | awk 'BEGIN{FS="[][]"}{split($2,a,":");totalms=(a[1]*3600+a[2]*60+a[3])*1000;print totalms+$3}'
74224180