CGI::Carp(3)

NNAAMMEE
       CCGGII::::CCaarrpp - CGI routines for writing to the HTTPD (or
       other) error log

SSYYNNOOPPSSIISS
           use CGI::Carp;

           croak "We're outta here!";
           confess "It was my fault: $!";
           carp "It was your fault!";
           warn "I'm confused";
           die  "I'm dying.\n";

DDEESSCCRRIIPPTTIIOONN
       CGI scripts have a nasty habit of leaving warning messages
       in the error logs that are neither time stamped nor fully
       identified.  Tracking down the script that caused the
       error is a pain.  This fixes that.  Replace the usual

           use Carp;

       with

           use CGI::Carp

       And the standard warn(), die (), croak(), confess() and
       carp() calls will automagically be replaced with functions
       that write out nicely time-stamped messages to the HTTP
       server error log.

       For example:

          [Fri Nov 17 21:40:43 1995] test.pl: I'm confused at test.pl line 3.
          [Fri Nov 17 21:40:43 1995] test.pl: Got an error message: Permission denied.
          [Fri Nov 17 21:40:43 1995] test.pl: I'm dying.

RREEDDIIRREECCTTIINNGG EERRRROORR MMEESSSSAAGGEESS
       By default, error messages are sent to STDERR.  Most HTTPD
       servers direct STDERR to the server's error log.  Some
       applications may wish to keep private error logs, distinct
       from the server's error log, or they may wish to direct
       error messages to STDOUT so that the browser will receive
       them.

       The carpout() function is provided for this purpose.
       Since carpout() is not exported by default, you must
       import it explicitly by saying

          use CGI::Carp qw(carpout);

       The carpout() function requires one argument, which should
       be a reference to an open filehandle for writing errors.

       It should be called in a BEGIN block at the top of the CGI
       application so that compiler errors will be caught.
       Example:

          BEGIN {
            use CGI::Carp qw(carpout);
            open(LOG, ">>/usr/local/cgi-logs/mycgi-log") or
              die("Unable to open mycgi-log: $!\n");
            carpout(LOG);
          }

       carpout() does not handle file locking on the log for you
       at this point.

       The real STDERR is not closed -- it is moved to SAVEERR.
       Some servers, when dealing with CGI scripts, close their
       connection to the browser when the script closes STDOUT
       and STDERR.  SAVEERR is used to prevent this from
       happening prematurely.

       You can pass filehandles to carpout() in a variety of
       ways.  The "correct" way according to Tom Christiansen is
       to pass a reference to a filehandle GLOB:

           carpout(\*LOG);

       This looks weird to mere mortals however, so the following
       syntaxes are accepted as well:

           carpout(LOG);
           carpout(main::LOG);
           carpout(main'LOG);
           carpout(\LOG);
           carpout(\'main::LOG');

           ... and so on

       Use of carpout() is not great for performance, so it is
       recommended for debugging purposes or for moderate-use
       applications.  A future version of this module may delay
       redirecting STDERR until one of the CGI::Carp methods is
       called to prevent the performance hit.

MMAAKKIINNGG PPEERRLL EERRRROORRSS AAPPPPEEAARR IINN TTHHEE BBRROOWWSSEERR WWIINNDDOOWW
       If you want to send fatal (die, confess) errors to the
       browser, ask to import the special "fatalsToBrowser"
       subroutine:

           use CGI::Carp qw(fatalsToBrowser);
           die "Bad error here";

       Fatal errors will now be echoed to the browser as well as
       to the log.  CGI::Carp arranges to send a minimal HTTP
       header to the browser so that even errors that occur in

       the early compile phase will be seen.  Nonfatal errors
       will still be directed to the log file only (unless
       redirected with carpout).

CCHHAANNGGEE LLOOGG
       1.05 carpout() added and minor corrections by Marc Hedlund
            lt;hedlund@best.com on 11/26/95.

       1.06 fatalsToBrowser() no longer aborts for fatal errors
       within
            eval() statements.

AAUUTTHHOORRSS
       Lincoln D. Stein lt;lstein@genome.wi.mit.edu.  Feel free to
       redistribute this under the Perl Artistic License.

SSEEEE AALLSSOO
       Carp, CGI::Base, CGI::BasePlus, CGI::Request,
       CGI::MiniSvr, CGI::Form, CGI::Response