if (-f $delTemp){
    unlink $delTemp or die "can't delete >$delTemp< file: $!";
}

##</code><code>##

my $a = 'a.txt';
my $b = 'b.txt';

copy $a, $b or die "can't copy $a to $b: $!";

die "can't find copied file $b: $!" unless -f $b;