How to wrap multiple programs in one main program?

perl Main.pl plot -file FILE -length LENGTH

perl Main.pl calc -length 20 -width 30

So Main.pl contains two sub-programs 'plot' and 'calc'. User can call anyone of them, based on their need.

#################  PLOT program here

#!/usr/bin/perl -w
use Getopt::Long;

my $data = "file1";
my $length = 4;
my $verbose;

GetOptions (
    "length=i" => \$length, 
    "file=s"   => \$data,
    "verbose"  => \$verbose
);

if (!@ARGV) {
    print "$0: Argument required.\n";
    exit 1
}


my $fh = read_fh ($data);
while (<$fh>) { print "$_\n"; }


##sub here
# Open and Read a file
sub read_fh {
    my $filename = shift @_;
    my $filehandle;
    if ($filename =~ /gz$/) {
        open $filehandle, "gunzip -dc $filename |" or die $!;
    }
    else {
        open $filehandle, "<$filename" or die $!;
    }
    return $filehandle;
}



################# CALC program here

#!/usr/bin/perl -w
use Getopt::Long;

my $width = 5;
my $length = 4;
my $verbose;

GetOptions (
    "width=i" => \$width, 
    "length=i"   => \$length,
    "verbose"  => \$verbose
);

if (!@ARGV) {
    print "$0: Argument required.\n";
    exit 1
}


my $total=$width*$length;
print $total;
[download]