I don't see how it would affect your shared memory problems at all, but note that: 
my $string .= 'appended stuff' if ($conditional1);

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Doesn't make much sense -- should just use the '=' operator instead of the '.=' operator, since there's nothing to append to since you're only just now declaring the variable. (Usage is fine in the last example) Maybe that's the problem since it's essentially doing something like this? 
my $string = $string . 'appended stuff' if ($conditional1);
#which is basically (or is it not and that's the problem?):
my $string = undef . 'appended stuff' if ($conditional1);

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To answer your 2) & 3), this code will leave $string as undef: 
my $conditional1 = 0;
my $string = 'blah' if $conditional1;
# $string is undef

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In reply to Re: How does my work with a trailing conditional by davidrw
in thread How does my work with a trailing conditional by DeaconBlues

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