If you have an array, @file, then you have to loop through it. m// cannot loop through an array in perl5 (maybe perl 6?). However, if you put the entire file into a scalar, now we can get somewhere:

my $file = join '', @file; # put it all in a single scalar
if ($file =~ m/(?:what you want to find.*){6}/)
{
  print "'what you want to find' was in the file at least 6 times.\n";
}
[download]

That said, grep would use up less space, which may be important for large files. The reason is because you're duplicating the file in both an array and a scalar. The obvious way to overcome that is to put it in the scalar to begin with - which means you don't have an array later if you want to look up lines in an array.

Of course, for really large files, you'll want to iterate through the file one line at a time to keep from loading 100MB of text into memory at once:

my $count;
while (<$fh>)
{
  $count++ while /what you want to look for/g;
  if ($count >= 6)
  {
    last;
  }
}
$fh->close();
if ($count >= 6)
{
  print "found 'what you want to look for' at least 6 times in the fil
+e.\n";
}
[download]

And, of course, this means you don't have the file in memory at all when you're done, which may not be what you want either.