FAQ 3.5 How do I debug my Perl programs?
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From: PerlFAQ Server on 2 Apr 2010 12:00 This is an excerpt from the latest version perlfaq3.pod, which comes with the standard Perl distribution. These postings aim to reduce the number of repeated questions as well as allow the community to review and update the answers. The latest version of the complete perlfaq is at http://faq.perl.org . -------------------------------------------------------------------- 3.5: How do I debug my Perl programs? (contributed by brian d foy) Before you do anything else, you can help yourself by ensuring that you let Perl tell you about problem areas in your code. By turning on warnings and strictures, you can head off many problems before they get too big. You can find out more about these in strict and warnings. #!/usr/bin/perl use strict; use warnings; Beyond that, the simplest debugger is the "print" function. Use it to look at values as you run your program: print STDERR "The value is [$value]\n"; The "Data::Dumper" module can pretty-print Perl data structures: use Data::Dumper qw( Dumper ); print STDERR "The hash is " . Dumper( \%hash ) . "\n"; Perl comes with an interactive debugger, which you can start with the "-d" switch. It's fully explained in perldebug. If you'd like a graphical user interface and you have "Tk", you can use "ptkdb". It's on CPAN and available for free. If you need something much more sophisticated and controllable, Leon Brocard's "Devel::ebug" (which you can call with the "-D" switch as "-Debug") gives you the programmatic hooks into everything you need to write your own (without too much pain and suffering). You can also use a commercial debugger such as Affrus (Mac OS X), Komodo from Activestate (Windows and Mac OS X), or EPIC (most platforms). -------------------------------------------------------------------- The perlfaq-workers, a group of volunteers, maintain the perlfaq. They are not necessarily experts in every domain where Perl might show up, so please include as much information as possible and relevant in any corrections. The perlfaq-workers also don't have access to every operating system or platform, so please include relevant details for corrections to examples that do not work on particular platforms. Working code is greatly appreciated. If you'd like to help maintain the perlfaq, see the details in perlfaq.pod. |