The code that tests for defined is in the section on CAVEAT/limitations, where presumably all kinds of testing including fork-bombs has led to the code shown and perlipc is a more advanced set of functionality. But in the head documentation of perlfork we see after a brief glimpse under the hood:

"To the Perl program that called fork(), all this is designed to be transparent. The parent returns from the fork() with a pseudo-process ID that can be subsequently used in any process-manipulation functions; the child returns from the fork() with a value of 0 to signify that it is the child pseudo-process".

So my disagreement extends also to your post. The OP wanted a solution to which fork is a possible answer I gave because it is simpler than threads. He did not ask for a history of trying to BREAK the fork function. Frankly these "contributions" are a sign of ego problems 'I know something too -- look at me!' which are apt to inhibit learning as well as disrupting the purpose of SOPW -- to answer the questions of OPs!! I will certainly consider the possibility of undef for more complex multiforking situations, but that hardly justifies raising it for this case, where sorry but it's way off topic!

One world, one people

In reply to Re^5: Doing every X seconds by anonymized user 468275
in thread Doing every X seconds by dideod.yang

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