Re: No inherited file handles with tie() and exec()

A tied handle is a Perl variable that Perl presents as a file handle, but isn't. When a program passes a tied handle to a Perl IO function, Perl calls a subroutine instead of doing IO calls. There's no way for Perl to cause a child process (that might not even be a Perl program) to call a sub in its parent instead of writing to a handle. As such, children cannot inherit tied handles or any other handle without a fileno.

Comment on Re: No inherited file handles with tie() and exec()

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Re^2: No inherited file handles with tie() and exec() by saintmike (Vicar) on Apr 15, 2009 at 02:27 UTC
Yeah, that makes sense. And I guess the reason why case #2 works with tie() and a forked process is that in this case the child knows about the tie()ed subroutine as well. Thanks!	[reply]
Re^3: No inherited file handles with tie() and exec() by ikegami (Patriarch) on Apr 15, 2009 at 03:03 UTC
I had a problem confirming your statement until I realize it's very unclear what you mean by a process "knowing a sub". The child gets a copy of the tied var, the sub and everything else in the process's memory space. It only works because 1) the child uses the copy of the tied var and 2) the child process doesn't expect to cause any changes in the parent.	[reply] [d/l]