54.1. Introduction to Logging

When logging is enabled, Webmin will record every action taken using it that has some effect on your system, such as the creation of a user or the changing of an Apache setting. Pages that do not actually change anything on your system, such as those that just display icons, list users, or show the current settings for some object will not write anything to the action log. In this way, it is different than the separate CLF log file that Webmin writes to /var/webmin/miniserv.log, which records every single page visited and image loaded.

Most actions performed in Webmin change configuration files, run commands, or execute SQL statements. When the recording of these file changes is enabled, the details of each will be included in the actions log so you can see exactly what Webmin did when you told it to create a UNIX user or delete a DNS zone. This can be helpful for understanding what is really going on behind the scenes if you are new to system administration or want to see how actions are implemented. Not all modules perform action logging, though, particularly those that are old or have been written by third-party developers.

As Section 51.4 “Setting Up Logging ” explains, logging can be turned on in the Webmin Configuration module. Basic action logging is enabled by default, but the recording of file changes is not. To gain the most benefit from the Webmin Actions Log modules, file changes should be logged as well. This will slow down the program slightly though, and consume more disk space for recording the changes.

Some types of action will never have any associated file changes logged, even if this feature is enabled. Such actions might perform all their work with network connections or modify a file so large that generating the differences between the old and new contents is impractical. Or file change logging may not have been implemented in the module at all.

The actual file in which actions are recorded is called /var/webmin/webmin.log. Its format is unique to Webmin but records the details of each action on a separate line in a simple text format. If the logging of file changes is enabled, the directory /var/webmin/diffs is used to store files containing the details of changes and commands used. Each file in this directory is named to match the ID of an action and contains the changes made to one file in diff format.

If you are looking for the files in /var/webmin on your system and cannot find them, check in /var/log/webmin instead. Some packaged versions of the software created by other Linux distribution vendors use this alternate directory to better fit in with the normal Linux log file layout.