use strict;
use CGI;
my $cgi = CGI->new;

my $host = $cgi->param('host');
print "<font color=green> Please Enter the UserID for $host: </font>";
print $cgi->textfield('USER','',10);
print "\t\t".$cgi->submit('action','Submit');
print $cgi->hidden( -name=>'server', -value => $cgi->param('host'));

if ($cgi->param()) {
  my $test= $cgi->param('action');
  if( $cgi->param('action') eq 'Submit') {
    my  $server = $cgi->param('server');
    print "Server is $server\n";
   
  };
};
__END__
>perl -w tmp.pl host=foo

Use of uninitialized value in string eq at tmp.pl line 13.
<font color=green> Please Enter the UserID for foo: </font><input type="text" na
me="USER"  size="10" />         <input type="submit" name="action" value="Submit
" /><input type="hidden" name="server" value="foo"  />