That's completely wrong.

1. Closing one end of a pipe doesn't cause close on the other end to return an error. 

$ perl -E'
   pipe($r, $w) or die $!;
   close($w) or die $!;
   close($r) or die $!;
   say "ok";
'
ok

[download]

2. Closing a pipe created by open(my $fh, '|-', ...) reads the process (calls wait). It's very appropriate to do this, whether the pipe is closed or not. Closing such a handle returns the same thing as system. 

$ perl -E'
   open(my $fh, "|-", "perl", "-e", "exit 123") or die $!;
   close($fh);
   die("$!\n") if $? == -1;
   die("Signal ".( $? & 0x7F )."\n") if $? & 0x7F;
   die("Error ".( $? >> 8 )."\n") if $? >> 8;
   say "ok";
'
Error 123

[download]

In reply to Re^4: Can't close pipe to invalid process by ikegami
in thread Can't close pipe to invalid process by cLive ;-)

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