Logging Requests and Errors

Apache records every request and any problems in log files. Logs are essential for debugging and monitoring traffic.

Default Log Locations

• Debian/Ubuntu: /var/log/apache2/
• Red Hat/CentOS: /var/log/httpd/

Access Log

The access log records each request. You define its format and path:

LogFormat "%h %l %u %t \"%r\" %>s %b" common
CustomLog /var/log/apache2/access.log common

Common format codes:

• %h: client IP address.
• %t: time of the request.
• %r: the request line.
• %>s: response status code.
• %b: size of the response.

Error Log

The error log captures problems and warnings:

ErrorLog /var/log/apache2/error.log
LogLevel warn

LogLevel controls how much detail is recorded, from debug to error.

Watching Logs Live

sudo tail -f /var/log/apache2/access.log
sudo tail -f /var/log/apache2/error.log

Per virtual host, you can set separate log files so each site has its own history. Always check the error log first when something does not work.