awkでカンマ編集

大昔、テキスト処理で数値のカンマ編集を実装（笑）する関数を書いていた記憶があったので、掘り起こし。たまたま必要になったものでwww

ykishi@dezembro /tmp % cat foo.sh 
# !/bin/sh

awk 'BEGIN{
  print comma(1234567890);
  print comma(123456789);
  print comma(12345678);
  print comma(1234567);
}
function comma(val) {
  a = val + "";
  len = length(a);
  s = len%3;
  from = len;
  to = from - s;
  buf = "";
  while( from > 0 ){
    if( from != to ){
      if( buf == "" ){
        buf =  substr(a, len - from + 1, from - to) + "";
      } else {
        buf = sprintf("%s,%s", buf, substr(a, len - from + 1, from - to) )
      }
    }
    from = to
    to -= 3;
  }
  return buf;
}'

ykishi@dezembro /tmp % ./foo.sh 
1,234,567,890
123,456,789
12,345,678
1,234,567
ykishi@dezembro /tmp %