It's a permissions issue.
Try the following

my $dir = "/whatever";
my $file = $dir."/file";
die "cannot write to $dir : $!" unless -W $dir;
[download]

I suggest you pick something in the form of /home/username/...

update: There ain't nothing special about /tmp as far as perl/DB_File is concerned. /tmp must exist, otherwise the program would have died.

MJD says you can't just make shit up and expect the computer to know what you mean, retardo! ** The Third rule of perl club is a statement of fact: pod is sexy.