This example will not catch errors with fork. You first need to test if the returned $pid is defined or not:

unless(defined(my $pid = fork)) {
  die "Could not fork: $!";  #fork failed
} elsif($pid) {
  sleep 1;                   #parent
  kill 9, $pid;
  wait;
} else {
  print "Yay!\n" while 1;    #child
}
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