Premature end of script error

Nik has asked for the wisdom of the Perl Monks concerning the following question:

Hello monks!

I have the following code and iam gettign those errors when index.pl trying to pass values to admin.pl and i dont see why.Also what I dont understand 2 things. Why the scripts dies prematurely although 'perl -c admin.pl' finds it syntactically correct and what is this uninitialized value in string that the error is complaining about.

[Fri May 25 13:06:47 2007] [error] [client 10.0.0.2] Premature end of 
+script headers: admin.pl, referer: http://dell/
[Fri May 25 13:06:47 2007] [error] [client 10.0.0.2] [Fri May 25 13:06
+:47 2007] admin.pl: Use of uninitialized value in string eq at D:\\ww
+w\\cgi-bin\\admin.pl line 26., referer: http://dell/
[download]

Here is the code, admin.pl is actually a decission making script on what script will be nextly ran depending on index.pl's form values.

#!/usr/bin/perl -w
use strict;
use CGI::Carp qw(fatalsToBrowser);
use CGI qw(:standard);
use DBI;
use POSIX qw(strftime);
use Encode;


my $title     =  param('title');
my $request   =  param('request');
my $orderlist =  param('orderlist');
my $remark    =  param('remark');
my $host      =  param('host');
my $date      =  param('date');

my $action    =  param('action');

my $gamefile  =  param('gamefile');
my $gamename  =  param('gamename');
my $gamedesc  =  param('gamedesc');
my $counter   =  param('counter');


#========================== REDIRECT TO PROPER SCRIPT ================
+==========
if( $action eq '&#928;&#945;&#961;&#945;&#947;&#947;&#949;&#955;&#943;
+&#945;!' )
{
    #========================= SHOW USER LIST TO PUBLIC ==============
+==========
    if( $title eq 'show users' ) {
        print redirect("/cgi-bin/show.pl?action=&#928;&#945;&#961;&#94
+5;&#947;&#947;&#949;&#955;&#943;&#945;!&request=$request");
        exit 0;
    }

    #================== SHOW USERS THAT HAVE DOWNLOADED FROM VAULT ===
+==========
    elsif( $title eq 'show downloads' ) {
        print redirect("/cgi-bin/show.pl?action=&#928;&#945;&#961;&#94
+5;&#947;&#947;&#949;&#955;&#943;&#945;!&request=$request");
        exit 0;
    }

    #========================= SAVE USER DATA TO DATABASE=============
+==========
    elsif( defined($title) and defined($request) and defined($orderlis
+t) and defined($remark) ) {
        print redirect("/cgi-bin/show.pl?action=&#928;&#945;&#961;&#94
+5;&#947;&#947;&#949;&#955;&#943;&#945;!&authname=$ENV{REMOTE_USER}&ti
+tle=$title&request=$request&orderlist=$orderlist&remark=$remark&host=
+$host&date=$date");
        exit 0;
    }
    else { print redirect("/data/private/") }
}


#========================== AUTHORIZE USER TO DOWNLOAD ===============
+==========
print redirect("/cgi-bin/vault.pl?authname=$ENV{REMOTE_USER}&gamename=
+$gamename")  if( defined($gamename) );
[download]

Comment on Premature end of script error Select or Download Code

Replies are listed 'Best First'.
Re: Premature end of script error by leocharre (Priest) on May 25, 2007 at 10:31 UTC
For one I would "use warnings;" - it gives you extra info. Just standard procedure to use that.. never know.. Also, why dont you check a little more on those values.. just snoop a little.. do this... add.. use Smart::Comments '###'; # and then after these... my $title = param('title'); my $request = param('request'); my $orderlist = param('orderlist'); my $remark = param('remark'); my $host = param('host'); my $date = param('date'); my $action = param('action'); my $gamefile = param('gamefile'); my $gamename = param('gamename'); my $gamedesc = param('gamedesc'); my $counter = param('counter'); # put this in there ### $title ### $request ### $orderlist ### $remark ### $host ### $date ### $action ### $gamefile ### $gamename ### $gamedesc ### $counter [download] Then fire up a terminal emulator (putty (ssh client), or use a real operating system- ) and do # tail -f /var/log/httpd/error_log ( where your server log resides) and when you fire up your cgi, you can see the ouput as it goes. Could be useful.	[reply] [d/l]
Re^2: Premature end of script error by blazar (Canon) on May 25, 2007 at 11:54 UTC
For one I would "use warnings;" - it gives you extra info. Just standard procedure to use that.. never know.. It doesn't give extra info wrt -w, but it is more flexible. (So yours is indeed a good recommendation.)	[reply]
Re: Premature end of script error by clinton (Priest) on May 25, 2007 at 10:33 UTC
It would have been helpful if you had told us which line was line 26, rather than making me count them. The error means just what it says : that a variable you are using in an `eq` comparison has not been initialised, ie it is undefined. Have a look at perldiag for an explanation of this warning. I am guessing that that variable is `$action`. You could change your `param` sub to always return a defined value. For instance: `sub param { my $key = shift; my $value = ....code to get value...; return defined $value ? $value : ''; }` [download] Update As blazar pointed out below, `param()` is from CGI, so you could do the following: `sub get_defined_param { my $value = param(@_); return defined $value ? $value : ''; }` [download] and replace all your call's to `param()` as follows: `my $title = get_defined_param('title'); my $request = get_defined_param('request'); my $orderlist = get_defined_param('orderlist'); my $remark = get_defined_param('remark'); my $host = get_defined_param('host'); my $date = get_defined_param('date'); my $action = get_defined_param('action'); my $gamefile = get_defined_param('gamefile'); my $gamename = get_defined_param('gamename'); my $gamedesc = get_defined_param('gamedesc'); my $counter = get_defined_param('counter');` [download]	[reply] [d/l] [select]
Re^2: Premature end of script error by blazar (Canon) on May 25, 2007 at 11:58 UTC
You could change your `param` sub to always return a defined value. For instance: It's not his `param` sub, it's CGI.pm's. Granted, he may write a wrapper around it, but he'd better take care of undefined values where they may matter.	[reply] [d/l] [select]
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Re: Premature end of script error by blazar (Canon) on May 25, 2007 at 12:01 UTC
Why the scripts dies prematurely although 'perl -c admin.pl' finds it syntactically correct Syntactical correctness does not protect one from runtime errors. `C:\temp>perl -cle "print 1/<>" -e syntax OK C:\temp>perl -le "print 1/<>" 2 0.5 C:\temp>perl -le "print 1/<>" 0 Illegal division by zero at -e line 1, <> line 1.` [download]	[reply] [d/l]