Read Multiple Files

my %data;
my @FILES = @ARGV;
# or maybe   @FILES = glob("some/directory/*.ext");

Since this is Perl, there are many ways to do it.

# 1. Open and load each file   
foreach my $file (@FILES) {
    local $/ = undef;
    open my $fh, '<', $file;
    $data{$file} = <$fh>;
}

# 1b. Using  map
%data = map {
   local $/=undef;
   open my $fh, '<', $file;
   my $data = <$fh>;
   $_ => $data
} @FILES;

# 2. Leverage your operating system
foreach my $file (@FILES) {
    $data{$file} = qx(/bin/cat "$file");
}

# 3. Use a module
use File::Slurp;
foreach my $file (@FILES) {
    $data{$file} = File::Slurp::slurp($file);
}

# 3b, using  map
use File::Slurp;
%data = map { $_ => File::Slurp::slurp($_) } @FILES;