题解 | #判断输入的是否为IP地址#

awk '{
    if($0~/^((25[0-5]|2[0-4][0-9]|[0-1]?[0-9]{0,2})\.){3}(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]{0,2})$/)
      print "yes"
    else if($0~/^([0-9]*\.){3}[0-9]*$/)
      print "no"
    else
      print "error"
  }' nowcoder.txt