=item B<-i> I<listfile>

Gives a file that lists the URLs to download and filenames to save
it: each line has a HTTP URL and a filename separated by whitespace.
The filename cannot contain whitespace.
[download]

Why that limitation? No URL can contain white space, but filenames can. So, split on the first white space, and perhaps remove extra white space before EOL to avoid nasty surprises.

    my($uri, $fnamej, $rest) = split " ", $spec;
    length($rest) and die "invalid spec (too many words, line $.): $sp
+ec";
[download]

    $spec=~s/\s+$//;
    my ($uri,$fnamej)=split /\s+/,$spec,2;
[download]

Alexander