my $rv = $sth->execute();
if (!$rv) {
     write_log (%log = (
          event_level => 'warning',
               role_id => "$global{$dmn}{'role_id'}",
               func_id => $func_id,
               message => "$dbh->errstr",
          )
);

Or like: 
system ("./1_setup_dirs.pl -a $object")
 if ($@) {
        write_log (%log = (
                event_level => 'error',
                role_id => "$global{$dmn}{'role_id'}",
                func_id => $func_id,
                message => "$@",
        )
    );