Something like this might do what you want:

my $data_str = join('', @data);

my $results1 =`command1 $data_str`;
my $results2 =`command2 $results1`;

print $results2;
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Using backticks will execute the command (command1/command2) and return the output. It'll also interpolate the variables so you can pass in the results of the previous command :-)