use POSIX ":sys_wait_h";

# do whatever that sets $SIG{CHLD} to 'IGNORE'

{
  local $SIG{CHLD} = 'DEFAULT';
   # do something interesting here, for example...
  my $return = system("gzip somefile");
  if($return != 0) {
    # handle exception here
  }
}
# reap any zombies that accumulated while
# $SIG{CHLD} was set to 'DEFAULT'
while ( (my $pid = waitpid(-1, WNOHANG)) > 0 ) {
  print "reaped $pid with status $?\n";
}


##</code><code>##

use Data::Dumper;

print Dumper(\%SIG);

$SIG{CHLD} = 'IGNORE';

print Dumper(\%SIG);