(my $res = system @args) and unlink $to_delete;


##</code><code>##

UFILE: while (@files) {
    #...
    system @args and do {
        unlink $to_delete;
        print LOG "'system @args' failed: ", $?;
        next UFILE;
    };
    system @other_args and
        print LOG "'system @other_args' failed: ", $?;
    #...
}