How to capture only errors in file while importing unity package in batchmode with no graphics

Hello Unity folks!
I am trying to import a unity package in batchmode with nographics in Jenkins environment to trigger a build. I am able to import it successfully. Now I want to capture errors like Compilation error, Precompiled Assemblies, Multiple/duplicate files or scripts error etc. only in a file. For that I am using -logFile <filePath> command, but this command saves all the unnecessary logs as well. which makes this file next to un-readable and by seeing that file, I am not able to find what actually went wrong or what was the error in that package, and because of that my build got failed. So please let me know the solution for this or is there any other way to do same.
Thanks in advance.