====== Logging ======
We use the ROS logging API for having programs produce output. See [[http://wiki.ros.org/roscpp/Overview/Logging|The official documentation for more details]].

There are 5 logging levels (ordered in increasing severity)
  * DEBUG
  * INFO
  * WARNING
  * ERROR
  * FATAL

Here are some [[http://wiki.ros.org/Verbosity%20Levels| general guidelines]] for when to use each level. If you use the FATAL message, your node should use a call to exit(nonzero value) very soon (if not immediately) after publishing the message.
====== Setting the Log Level ======
By default, only severity >= INFO is logged and displayed. There are several ways of changing the log level of a particular node, or all nodes.

===== For a Single Node =====
Use the rosconsole command from the command line. Note this can only be applied to a currently running node, so it isn't very useful if you have debug messages in the startup of your node that you want to see.

===== For all Nodes =====
Modify your .bashrc file and add the following line:
  export ROSCONSOLE_CONFIG_FILE="$HOME/.rosconsole.config"
Then run:
  echo "log4j.logger.ros=DEBUG" > ~/.rosconsole.config
You can replace DEBUG with another log level.

This is useful if you want to see debugging messages for all the nodes.

===== Programatically =====
Yes, you can make a node set its log level by itself! Check out this [[http://wiki.ros.org/roscpp/Overview/Logging#Setting_Verbosity_Levels | example]].