my $sleep = 1;
$SIG{ALRM} = sub { $sleep = 0; };
$SIG{CHLD} = sub { ... child ends here ... };
...

if (... $pid == 0) {
   ... child here
} else {
  $sleep = 1; alarm (1);
  wait_for_signal while $sleep; # search for POSIX, SigAction, ...
}
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