Linux Troubleshooting Methodology

Studying for the CompTIA Linux+ 005 exam I came across a well known and well used topic; troubleshooting. Early in my career when I worked as a programmer I always sought out opportunities to troubleshoot projects. I worked as a field engineer for a year identifying, investigating and working to resolve issues with my employers products. I’ve been working with Linux for years and the troubleshooting method presented in the CompTIA Linux+ (XK0-005) exam objectives were natural for me.

My Linux troubleshooting method is to:

  • Identify – What is the trouble?
  • Scope – What is the extent of the trouble? Where do I deploy the caution tape? One user? One computer? One network? One distro?
  • Probable Cause – What’s my hypothesis? What is most likely causing the trouble?
  • Test – How can I test my hypothesis about the probable cause?
  • Plan of Action – If I have proven my hypothesis regarding the trouble; what is the action I need to take to correct the trouble? Given I need to go forward and address the trouble; what impact will that have? Other users? Other computers? The network?
  • Implement – Execute my plan of action.
  • Verify – Did my now executed plan of action address the trouble? Does everything that worked before I implemented my action still work?
  • Preventative – Do I need to look for this trouble elsewhere? What are the characteristics of this trouble and where do I look for them? Can I find some message in the logs? Does that message before, during or after the trouble? Do I need to warn others about this trouble?
  • Root Cause / After Action – How did I get from the original report of trouble to this point where the trouble has been resolved? If I had it to do over again is there anything I could do in order to resolve the trouble better or faster?

In my own preparation for the CompTIA Linux+ certification I spent several months preparing for the 004 version of the exam. When the Linux+ XK0-005 exam objectives came out I quickly switched over. The 005 exam objectives (dated July 2022) were much clearer to me as they are based on using systemd software suite. I achieved Linux+ certification in late 2022.