As others have already pointed out, this code isn't overly portable because of the dependency on the output of ps. A better solution would be to make use of Proc::ProcessTable which I have reviewed previously here. eg.

#!/usr/bin/perl -w
use strict;
use Proc::ProcessTable;
my $proc = Proc::ProcessTable->new;
foreach (@{$proc->table}) {
    if ($_->pid eq getppid) {
        print "The parent pid is ", getppid, "\n";
        print "The name of the parent shell is ", $_->cmndline, "\n";
    };
};
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Ooohhh, Rob no beer function well without!