http://www.csbio.sjtu.edu.cn/cgi-bin/MEMBRAIN.cgi

for the form's CGI!

... but without submitted form parameters it'll only return an error.

Yes, of course, I added some:


my $url = 'http://www.csbio.sjtu.edu.cn/cgi-bin/MEMBRAIN.cgi';
my $mech = WWW::Mechanize->new (timeout=>1000);
$mech->get($url);

        $mech->submit_form
        (
            form_number => 1,
            fields      => 
            {
                #textarea name | value
                S1 => ">$id\n$seq",

                #Radio button name | prediction type
                R4    =>  TOPpre,

                #Radio button SIGNAL | I do not know if I have a signa
+l peptide
                R2    =>  SignalYES,

                #Radio button ORGANISM | Human, Plant, Animal, OEuk, G
+pos, Gneg, 
                R3    =>  Human,

                #Fill in email
                email => 'testmail@gmail.com'
            }
        );
[download]

Your code is bad. You need to quote strings (hash values). Additionally S1 parameter looks a bit strange with the new line embedded - are you sure?

Here is the curl equivalent of a successful run I did earlier (I broke the lines for readability). You can see that by opening developer tools on Firefox. I have done a successful submission using this from a Linux terminal:

curl 'http://www.csbio.sjtu.edu.cn/cgi-bin/MEMBRAIN.cgi' -H 'User-Agen
+t: XXX'
-H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,imag
+e/webp,*/*;q=0.8'
-H 'Accept-Language: en-US,en;q=0.5' --compressed
-H 'Referer: http://www.csbio.sjtu.edu.cn/bioinf/MemBrain/'
-H 'Content-Type: application/x-www-form-urlencoded'
-H 'Origin: http://www.csbio.sjtu.edu.cn'
-H 'DNT: 1' -H 'Connection: keep-alive' -H 'Upgrade-Insecure-Requests:
+ 1'
--data-raw 'mode=string&S1=NTLRVPDILALVIFAVVFLVGVLGNALVVWVTAFEAKRTINAI
WFLNLAVADFLACLALPALFTSIVQHHHWPFGGAACSILPSLILLNMYASILLLATISADRFLLVFKPAW
CQRFRGAGLAWILCAVAWGLALLLTIPSALYRVVREEYFPPKVLCGVDHDKRRERAVAIVRLVLGFLWPL
LTLTICYTFILLRTWSARETRSTKTLKVVVAVVASFFIFWLPYQVTGIMMSFLEPSSPTFLLLKLDSLCV
+S
FAYINCCINPIIYVVAGQGFQKSLPELLREVLTEESVVR&R5=on&S2=&R4=TOPpre&TOPpre=on
&R2=SignalYES&R3=Human&email=abc%40xyz.com&B1=Submit'
[download]

You can infere a couple of things from the above: 1) the correct POST params from --data-raw. 2) No cookies are required. So either continue with Mech but use the correct url and POST params or use LWP::UserAgent with a browser-like user-agent string

sarcasm on: if the cgi script you are accessing is also programmed by biologists all bets are on (off, whatever).

bw, bliako

you are still confusing the two URIs, see my explanation here.

The form is a part of the page you get°

Maybe you should read up on some HTTP/HTML basics first.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}

°) that's the address you see in your browser, mechanize will extract the address of the CGI automatically if you specify which form to use.