There are three primary kinds of log files available at NearlyFreeSpeech.NET:
- Access logs
- Error logs
- Rewrite logs
All three are (if enabled) found in the /home/logs directory of your site.
Access logs are the most common type. Each line in the access log represents one access to your website. It contains a variety of information, like what IP address accessed your site, what they accessed, what web browser they used, etc. This is the type of log file that is most commonly used by analytics programs like AWStats and analog.
Error logs contain information about problems with your site. Although they contain lots of generic information, like records of attempts to access pages that don't exist, they are most important to web developers and people with complex software loaded on their site. Whenever software running on a site has a problem, it should (but doesn't always) say something about the problem in the error log. Finding that message can save you fruitless hours of wondering what the heck is wrong with your site.
If you ask for help troubleshooting a problem, on our forum for example, the first thing people will typically ask is whether you have your site's error log enabled and, assuming you do, what it says. To save time, it's often helpful to make sure it's enabled, say so in your question, and include any relevant log entries from around the time the problem occurred.
The third type, rewrite logs, are a bit more special-purpose. Rewrite logs track internal changes made to URLs by Apache. They're generally only useful when debugging these changes if you've set up your own rewriting rules, because the time it takes to write rewrite logs to our disk can slow your site to a crawl if you use a lot of them. If you don't know what a rewrite is or why you'd want to log them, you should definitely leave this one turned off.