Yocto's logging functions (Python, shell)

Yocto provides logging functions in both Python and shell to help you log when debugging. In this article, we will briefly introduce the types of logging functions and the similar but slightly different Python and shell logging functions.

Types of logging functions

• python: bb.fatal, bb.error, bb.wran, bb.note, bb.plain, bb.debug
• shell script: bbfatal, bberror, bbwarn, bbnote, bbplain, bbdebug

Function name	Description
bb.fatal, bbfatal	message and abort the build.
bb.error, bberror	It outputs an error but doesn't break the build.
bb.warn, bbwarn	Print only a warning message.
bb.note, bbnote	Print a message for the user's information.
bb.plain, bbplain	Print a message
bb.debug, bbdebug	Add debugging information that is displayed based on the debug level.

Differences between Python and shell logging functions

• Python logging functions: Viewable directly in the console and stored in the execution log inside build/tmp/log/cooker/<machine>.
• Shell script logging functions: Output to individual task logs, this information can be found in each task log file in the build/tmp/work/<arch>/<recipe name>/<software version>/temp directory

As you can see, there are different places to view the final logging results, so it's important to be familiar with them and use them for debugging purposes.