Merging and Splitting Log Files

When you have a cluster of web servers serving the same content, it is often necessary to merge logs from all servers into a unique log file before passing it to analysis tools. Similarly, if a single Apache server handles several virtual hosts, sometimes it is necessary to split a single log file into different files, one per each virtual host. This can be done at the web server level, as explained in the next section, or by post-processing the log file. Both Apache 1.3 and 2.x come with a support script file named split-logfile. It can be found in the support/ directory of the Apache source distribution.

The logtool project provides a collection of log manipulation tools, and can be found at http://www.coker.com.au/logtools/.

The vlogger tool allows splitting a single log stream into several virtualhost-specific log files, as well as being able to replace tools such as cronolog, as explained in a previous section. It can be found at http://n0rp.chemlab.org/vlogger/.