Error Log For Cgi
Contents |
through several errors and how they appear in the error log, and finally consider some ways in which we can use the error log to make debugging easier. As discussed in my last column apache cgi error log (LJ, Issue 34, WWW section), debugging CGI programs is often more difficult than debugging their perl cgi error log non-CGI counterparts, if only because our programs aren't interacting directly with the user's terminal. We have only one chance to get input
Cgi Script Error
from the user—when the program is invoked—and only one chance to send a response back to the user—just before the program terminates, in the HTML that our program creates. This difficulty is complicated further by the fact that
Cgi Error 500
running CGI programs correctly requires that a number of other items be in place. For example, you must set the permission bits correctly, the web server must be configured to serve CGI programs from your directory, and the correct version of Perl (if you are using Perl for your CGI tasks) must be installed. None of this is very difficult, and it's particularly uncomplicated when compared with the full administration of a Unix system, but it's cgi error premature end of script headers not quite as simple as compiling and executing other, non-CGI programs.In the last article in this series, we looked at techniques that you can use when things go wrong. But what happens when all of the permissions and directories are set correctly and you still end up getting a mysterious error on your browser?The answer is that while web servers send a generic error message back to the user's web browser, they also keep an “error log,” a file into which information about each error is placed. This month, we will examine the error log to see what it contains, look through several errors and how they appear in the error log, and finally consider some ways in which we can use the error log to make debugging easier.Why an Error Log?As Unix programmers are well aware, programs typically have at their disposal three basic file descriptors: standard input (stdin), standard output (stdout), and standard error (stderr).Standard input is typically associated with the user's keyboard; when you are entering text in Emacs or similar program, the program is probably collecting your keystrokes via stdin. Standard output, by contrast, typically goes back to your console—either the window into which you are typing or the entire screen.Standard error is normally sent to the user's console, and thus is often confused with stdout. But the two are comple
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or
Cgi Error Ah01215
posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss software error cgi Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only cgi login takes a minute: Sign up How can I troubleshoot my Perl CGI script? up vote 86 down vote favorite 55 I have a Perl script that isn't working and I don't know how to start narrowing down the problem. What http://www.linuxjournal.com/article/2055 can I do? Note: I'm adding the question because I really want to add my very lengthy answer to Stackoverflow. I keep externally linking to it in other answers and it deserves to be here. Don't be shy about editing my answer if you have something to add. perl cgi share|improve this question edited Jan 29 '10 at 20:53 community wiki 2 revsbrian d foy 2 @Evan - this claim is incorrect - it is simply a matter of rep. http://stackoverflow.com/questions/2165022/how-can-i-troubleshoot-my-perl-cgi-script I think this should have remained without CW, but I'm glad the OP has some decent answers. –Marc Gravell♦ Feb 4 '10 at 5:33 @Marc, at the time the question was not CW, so we couldn't edit it, now that the OP, and the person with the answer (which he disclaimed in the question) has marked both as CW I can edit it. –Evan Carroll Feb 4 '10 at 16:17 5 @Evan - my point is simply that even as non-CW it still is editable - if you have enough karma; 100 for CW, 2k otherwise. So now you have 2060 you should be able to edit non-CW posts. –Marc Gravell♦ Feb 4 '10 at 16:39 Ah, I didn't know the magic point was at 2000 exp –Evan Carroll Feb 4 '10 at 17:41 1 @Evan, the magic points are listed in the tooltips in the right-hand column here: stackoverflow.com/privileges –cjm Nov 28 '10 at 21:01 | show 1 more comment 8 Answers 8 active oldest votes up vote 108 down vote accepted This answer is intended as a general framework for working through problems with Perl CGI scripts and originally appeared on Perlmonks as Troubleshooting Perl CGI Scripts. It is not a complete guide to every problem that you may encounter, nor a tutorial on bug squashing. It is just the culmination of my experience debugging CGI scripts for ten (plus!) years. This page
Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring http://serverfault.com/questions/57602/how-to-display-cgi-bin-errors-instead-of-500-in-apache developers or posting ads with us Server Fault Questions Tags Users Badges Unanswered Ask Question _ Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top How to display cgi-bin errors instead of 500 in Apache? up vote 1 down vote favorite 1 I'm interested cgi error in getting errors from cgi-bin scripts inside the browser like the PHP errors. The cgi script can be Perl, Python, Ruby, binary or something else. I'm not interested about a specific solution - I'm looking for something that should work with any script. I want to use is on a development/test server not in production. I am aware that in production you should not display the error_log to the user. I'm looking for a script to be used to replace cgi error log ErrorDocument inside Apache. I had one in the past but I lost it. apache-2.2 log-files cgi 500 share|improve this question edited Aug 23 '09 at 13:11 asked Aug 23 '09 at 12:48 sorin 2,099103663 add a comment| 4 Answers 4 active oldest votes up vote 1 down vote Basically as radius says, catch & display the error rather than let it pass through. In perl, see the Carp module: http://search.cpan.org/~nwclark/perl-5.8.9/lib/Carp.pm share|improve this answer answered Aug 23 '09 at 14:00 Devin Ceartas 1,308712 add a comment| up vote 0 down vote I think that using a wrapper can do that. Write a script that always return 0 so that apache will never do error 500 for it. In this script launch the true script to execute and catch STDOUT and STDERR to be able to send them back to the client. share|improve this answer answered Aug 23 '09 at 12:55 radius 8,3841541 add a comment| up vote 0 down vote Not quite what you asked but how about just exposing the logs through an alias? Alias /var/log/httpd /apache-logs