I want to access and grep Jenkins Console Output as a post build step in the same job that creates this output. Redirecting logs with >> log.txt is not a
You can install this Jenkins Console log plugin to write the log in your workspace as a post build step.
You have to build the plugin yourself and install the plugin manually.
Next, you can add a post build step like that:
With an additional post build step (shell script), you will be able to grep your log.
I hope it helped :)