FAQ 9.3 How can I get better error messages from a CGI program?

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9.3: How can I get better error messages from a CGI program?

Use the CGI::Carp module. It replaces "warn" and "die", plus the normal
Carp modules "carp", "croak", and "confess" functions with more verbose
and safer versions. It still sends them to the normal server error log.

use CGI::Carp;
warn "This is a complaint";
die "But this one is serious";

The following use of CGI::Carp also redirects errors to a file of your
choice, placed in a BEGIN block to catch compile-time warnings as well:

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

You can even arrange for fatal errors to go back to the client browser,
which is nice for your own debugging, but might confuse the end user.

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

Even if the error happens before you get the HTTP header out, the module
will try to take care of this to avoid the dreaded server 500 errors.
Normal warnings still go out to the server error log (or wherever you've
sent them with "carpout") with the application name and date stamp
prepended.



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