#!/usr/bin/perl  
#mv *.xxx *_xxx
#usage mv.pl xxx yyy
open(FN,"find . -name \"*$ARGV[0]*\" -print |");
while ($fn = <FN>){
  chop($fn);
  $fn =~ /\.\/(.*)\.(.*)/;
  print STDERR $1," ",$2,"\n";
  rename($fn,"\.\/$1_$2");
}