Q: In bash scripting, what is the significance of the exit code `$?`, and what does an exit code of `0` mean?
The specialized variable $? holds the numeric exit code of the absolute last command executed in the terminal.
#Linux #Linux / SRE — Scenario-Based Interview Questions #L1 #SRE #Systems #Troubleshooting
🎙️ Candidate Opening & Architectural Context
""Never reboot a server blindly; always capture top process telemetry, lsof descriptors, and thread dumps first. The interviewer is testing: Basic shell scripting, POSIX exit conventions.. 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
Production Solution & Architecture
The specialized variable $? holds the numeric exit code of the absolute last command executed in the terminal. In Linux architecture, an exit code of 0 means success (the command executed perfectly without errors). Any numeric exit code greater than 0 (e.g., 1, 127, 255) means failure. This is why scripts often check if [ $? -eq 0 ] to decide whether to proceed to the next step or halt and throw an error.
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: The specialized variable $? holds the numeric exit code of the absolute last command executed in the terminal.."
⚡ 60-Second Elevator Pitch Talking Points
- Immediate Triage: The specialized variable $? holds the numeric exit code of the absolute last command executed i
- Run targeted verification commands before modifying configuration.
- Automate permanent guardrails (CI check, alerts, IaC policy) to prevent recurrence.
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