grep -f File1 File2

#! /opt/third-party/bin/perl
                                                                                                                                              
$i = 1;
open(fh, "small") || die "unable to open the file <small>";
while( chomp($content = <fh>) )
{
  $fileHash{$content} = $i;
  $i += 1;
}
close(fh);
                                                                        
open(file, "big") || die "Unable to open the file <big>";
while ( chomp($rec = <file>) ) {
  print "\nMatch:$rec" if exists $fileHash{$rec} ;
}
close(file);
                                                                        
exit 0

comm -12 file file2

sort -o tmpfile2 file2
sort -o tmpfile1 file1
comm -12 tmpfile1 tmpfile2