sub test;

test 'b.bat';
test 'call b.bat';
test 'b.bat & exit errorlevel';

test 'bb.bat';
test 'call bb.bat';
test 'bb.bat & exit errorlevel';

sub test
{
    local $\ = "\n";
    print "@_";
    system @_;
    print '  exit code is: ', $? >> 8;
}