The command line interface

You access logging on Forge with the --logLevel option. Its usage is as follows: --logLevel (<topicName>=)<logLevel>

By selecting a level you are requesting all feedback at of that level of severity and greater. For example, by specifying the WARN level, you receive WARN, ERROR, and FATAL messages.

The --logLevel option sets either the default log level, the topic log level, or both:

The default log level provides global logging for the component:
```
forge --logLevel WARN 
```
This example logs all WARN level or higher messages.

Note: Forge defaults to log all INFO or higher level messages if a default level is not specified.
The topic log level provides logging at the specified level for just the specified topic:
```
forge --logLevel baseline=DEBUG
```
This example overrides the default log level and logs all DEBUG messages and higher in the baseline topic.
If two different log levels are specified, either globally or to the same topic, the finer-grained level is used:
```
forge –logLevel INFO –logLevel WARN
```
In the case of this example, all INFO level messages and higher are printed out.

It is possible to specify both default and topic level logging in the same command to filter the feedback that you receive. For example:

forge --logLevel WARN --logLevel config=INFO --logLevel update=DEBUG

This command works as follows:

It logs all WARN or higher messages, regardless of topic.
It logs any message flagged with the config topic if it is INFO level or higher.
It logs any message flagged with the update topic if it is DEBUG level or higher.