use strict;
use warnings;

[...]

my $pid = fork;
die "Failed to fork: $!\n" unless (defined $pid);
unless ($pid) {
  exec '/path/to/program', 'argument';
  die "Failed to exec: $!\n";
}

[...]

{
  local $SIG{CHLD} = 'IGNORE';
  kill TERM => $pid or die "Failed to kill $pid: $!\n";
}