Q: After a kernel upgrade, the server boots into the old kernel instead of the new one. How do you fix this?
The GRUB bootloader controls which kernel is loaded at boot. After a kernel upgrade, the default boot entry may still point to the old ke...
#Linux #Allow user 'deploy' to restart nginx and read syslog only #L1 #SRE #Systems #Troubleshooting
🎙️ Candidate Opening & Architectural Context
""In an interview, I explain my systematic Linux troubleshooting methodology using Brendan Gregg's USE method. The interviewer is testing: GRUB bootloader configuration, default kernel selection.. I structure my answer around systematic triage first, root cause analysis second, and permanent remediation third.""
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🛠️ Production Runbook & Step-by-Step Resolution
1️⃣
Initial Diagnostics & Root Cause Analysis
The GRUB bootloader controls which kernel is loaded at boot. After a kernel upgrade, the default boot entry may still point to the old kernel.
- List installed kernels:
- Set the new kernel as default:
- Regenerate GRUB config (if needed):
2️⃣
Remediation & Permanent Safeguards
To fix: Or by menu index: After reboot, confirm with uname -r that the new kernel is running.
grubby --default-kernel # Shows current default
awk -F\' '/menuentry/ {print $2}' /boot/grub2/grub.cfg # Lists all entries- Verify and reboot:
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: List installed kernels:."
⚡ 60-Second Elevator Pitch Talking Points
- List installed kernels:
- Set the new kernel as default:
- Regenerate GRUB config (if needed):
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