An 'our' variable (or any normal variable for that matter) is not shared between parent and child after a fork.

our $x = 1;

my $f = fork;
die $! unless defined $f;
if ($f) {
    # parent
    sleep 1;
    print "parent: x=$x\n"; # prints 1
}
else {
    $x = 2;
    exit;
}
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Dave.