undef will evaluate to 0 in numeric context, so you'll really want: 
if (!defined(my $pid = fork)) {
    print "Oh no\n";
} elsif ($pid == 0) {
    print "in child\n";
} else {
    print "in parent\n";
}

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In reply to Re^2: Forking problems by pc88mxer
in thread Forking problems by fawkin

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