sub file_to_list {
   my $name = shift or die "must have name to read";
   open (FILE, '<', $name) or die "can't read from $name: $!";
   chomp(my @data = <FILE>);
   return @data;
}

sub list_to_file {
   my $name = shift or die "must have name to write";
   open (FILE, '>', $name) or die "can't write to $name: $!";
   print FILE "$_\n" for @_;
}

my @foo = file_to_list('file.in');

print "$_\n" for @foo;

list_to_file('file.out',@foo);