my $timeout = 5;
eval {
    local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required
    alarm $timeout;
    my $ret = qx/ping db01/;
    alarm 0;
};
if ($@) { # timed out
    print "timeout handling ($! - $@) ...\n";
    die unless $@ eq "alarm\n";   # propagate unexpected errors
}
else { # didn't
    print "no timeout timeout handling...\n";
}