I don't know what's wrong. Thanks in advance.

#!/usr/bin/perl -w
use CGI qw(:all);
use strict;
my $name;
my $passwd;
my $cryptpasswd;
my $name=param('name');
my $passwd=param('passwd');
chomp $name;
chomp $passwd;

if (my $name eq "")
{ print "Please input your name!\n"; exit;}

if (my $passwd eq "")
{ print "Please input password!\n"; exit;}

my $cryptpasswd=crypt($passwd,"ss");
open (PASSWD,"/var/www/cgi-bin/shadow")||die "Fail to open file :$\n";
$shadow=;
close(PASSWD);
@shadow=split(/:/,$shadow);
print "$name\n";
print "$cryptpasswd\n";
print "$shadow[0]\n";
print "$shadow[1]\n";
if ((my $name eq $user) && (my $cryptpasswd eq $passwdshadow)) { print "Thanks!\n"; exit;}
else { print "Wrong input£¡\n"; exit;}

I think it's looking for a module you don't have declared

you using lots of variables that you havent declared.
Also, your declaring variables twice with the use of the 'my' statement

I think you should declare all your vars up to with 'my'

You dont use 'my' every time you use the var there after.

Also, i think what your trying to do with:
$shadow=;

would be better written as

$shadow=<PASSWD>;

That should read the file into the $shadow variable.
The next next line will then 'split' the var into separate elements and stick these in the @shadow array.

Also, what is $passwdshadow in the line:
if ((my $name eq $user) && (my $cryptpasswd eq $passwdshadow)) { print "Thanks!\n"; exit;}


this is the only time you've used this var so $cryptpasswd will never be equal to $passwdshadow

hth

Martin