What about this too (borrowing from hotshot's example):

my $bigStr = 'Once upon a time there was a little programer';
my $littleStr = 'time';

if ($bigStr =~ /^(.*?)$littleStr/) {
  my $position = length($1);
  print "Found $littleStr at position $position\n";
  # Do whatever depending on the position returned
}
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Since you mentioned that you'd be looking for the string in more than one position, this will allow you to do the match once.