use strict;

sub filegrep {
  ...
}

my @files = filegrep('Match this!');


##</code><code>##

sub filegrep {

#         1         2         3         4         5
#12345678901234567890123456789012345678901234567890123456
 my@k;for(<*>){open F,$_;push@k,$_ if grep/$_[0]/,<F>};@k
}