debuggng PERL

[DaveC426913]

1] How can I reliably debug PERL by displaying the contents of variables? What if the script hasn't actually created a page yet, but might?

The pages I'm debugging are doing various things that might or might not generate an HTML page, redirect to another page or run a shell script. The very act of displaying a variable may mess with the operation of the script (especially if it hasn't printed the header yet).

While I'm at it, same question about shell scripting.



2] I run my PERL script (createdir.pl) but, rather than being redirected, it displays this - I don't understand what it is telling me:

Status: 302 Moved Location:

http://staging2.blahblah/event.php?c=1651

It should be going to that URL (which does exist). Why isn't it? Does 'moved location' simply mean "I would go there if I could find it"?


Here are the relevant parts of the code (there's other bits, hopefully I've pared them out correctly):

#!/usr/bin/perl -w

use strict; # Activate compile-time syntax checking
use CGI; # Needed for CGI environment
use CGI::Carp qw(fatalsToBrowser); # Throw errors as HTML pages
use File::Copy; # Much easier for duplicating the sample conf

my $thecgi = new CGI;
my ($instructions,$redirect,$code,$clientDB,$clientName,$eventID,$eventName,$mode);
print "Content-type: text/html\n\n";
newEvent();

$code = $thecgi->param("c");
$instructions = "$mode $clientDB $eventID";
$redirect = "

http://staging2.blahblah/event.php?c=$code";

#####
my $cmd = "./createdir.sh $instructions";
my $result = system($cmd);
$result >>= 8; # shift 8 bits

select (STDOUT);
print $thecgi->redirect( $redirect );
exit 0;
#####

function newEvent(){
etc, etc.
}
exit 0;

 

[icrf]

2 is easy, 1 all I can really say is check the FAQ's here and in the CGI forum for a few pointers. Others may chime in with their debugging preferences, but I haven't done much complex stuff with it to be of any help.

You can't print a standard Content-type mime if you're doing a redirect. The redirect itself sends different codes that tell the browser what to do. Otherwise, the browser is just doing what you told it to do ten lines earlier: treat the following content as text/html. (you can/should send that with CGI.pm's header(), too)

- Andrew
Text::Highlight - A language-neutral syntax highlighting module in Perl
also on SourceForge including demo

 

[PaulTEG]

simple print statements to a logfile are generally what I use for debug information. I tend to use indenting for loops as well.

HTH

Paul
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