What are your "globally scoped varbinds"? The portion of code you show seems to be ok, although I'd rewrite it as

open my $ps, '-|', 'ps -eo pid,comm,args' or
  die "Can't run 'ps': $!\n";
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What about some more? I'm sure I would have no problems reading the output of it like thus:

my $output = do {
    open my $ps, '-|', 'ps -eo pid,comm,args' or
      die "Can't run 'ps': $!\n";
    local $/;
    <$ps>;
};
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Also, you may have chosen ps(1) solely as an example, but you may also be interested in Proc::ProcessTable.