Apart from using 'my', there seem to be other good habits to get into from reading the OP:

- using close,

- avoiding unecessary loops that repeat the same functionality - for example the OP code opens and reopens the same file and slurps it for each line of another file.

- if the container for the filehandle goes out of scope inconveniently, just transfer it to one that does have adequate scope.

Or to put that all into code:

#!/usr/bin/perl 
use strict;
use warnings;
open my $fh1, "file1" or die "$!: file1";
my $fh2;
my @file2;
{ local $/ = undef;
  open my $fh, "file2" or die "$!: file2";
  $fh2 = $fh;
  @file2 = <$fh>;
}
close $fh2; # could have closed in the above block, but just illustrat
+ing a point about scope here
while (<$fh1>) {
    print;
    print @file2;
}
close $fh1;
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