Why does the history command sometimes show duplicate commands with different numbers after restarting the shell?

hard📝 Conceptual Q10 of 15

Linux CLI - Environment and Configuration

Why does the history command sometimes show duplicate commands with different numbers after restarting the shell?

ABecause the history command caches commands in memory only

BBecause the shell resets command numbers on each start

CBecause duplicate commands are merged automatically

DBecause the history file appends new commands without removing duplicates

Step-by-Step Solution

Solution:

Step 1: Understand history file behavior
The history file appends commands each session, so duplicates accumulate if not cleaned.
Step 2: Check command numbering
Command numbers increase but duplicates remain because file is appended, not overwritten.
Step 3: Evaluate other options
Shell does not reset numbers to 1 each time; history caches in memory but also reads file; duplicates are not merged automatically.
Final Answer:
Because the history file appends new commands without removing duplicates -> Option D
Quick Check:
History file appends commands causing duplicates [OK]

Quick Trick: History file appends commands; duplicates appear if not cleaned [OK]

Common Mistakes:

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