Tutorial   #chatgpt #deepseek #genai #promptengineering  

Overview

Today (2/11/2025) I ran into a problem that can be solved by Linux shell commands, but I don't know the exact commands needed to solve it, so I tried Google search engine which is my traditional approach to this kind of problem. I also tried AI chatbots including #ChatGPT and #DeepSeek and was impressed with their performance. Overall, lessons learned are:

• All 3 approaches did help me find solution to the problem
• Regarding quality of solutions, search engine approach lags behind GenAI approach with Caveat below
  • Caveat: GenAI approach does require me to spend more brain power than Search Engine to come up with a more clearly-stated problem statement, however, the extra spent brain power did get me rewarded with some surprisingly new knowledge brought by GenAI chatbots.
• within #GenAI chatbots, DeepSeek performs as good as ChatGPT.

Problem

Given a large text file and a string, find line in the file that matches the string, and also show surrounding lines.

Search Engine Approach

To solve this problem, here are my steps using search engine:

• Googled keyword find line number of a string in file linux
  • Google gave grep -n "your_string" command in search result
• Googled keyword show certain lines of a file linux
  • based on search result, I constructed the solution below which worked as expected

$ grep -n "ABCD1234" ABC.txt

output: 1097994474:ABCD1234

$ head -1097994476 ABC.txt | tail -5

output: desired output

GenAI Approaches

As part of #PromptEngineering effort, I constructed the prompt by rephrasing the problem statement more clearly as following and used it in both ChatGPT and DeepSeek, I also tried the same prompt in Google.

Please give me shell commands to complete this task on Linux: given a text file, ABC.txt, with multiple lines that contains a string "ABCD1234" only once in the file, show the line in the file that contains the string "ABCD1234" as well as 2 lines before it and 2 lines after it.

Here are how they performed.

DeepSeek R1

Output from DeepSeek R1

You can use the grep command with the -B (before) and -A (after) options to achieve this. Here's the command:

bash grep -B 2 -A 2 "ABCD1234" ABC.txt

Explanation:

• grep: The command used to search for text within files.
• -B 2: Shows 2 lines before the matching line.
• -A 2: Shows 2 lines after the matching line.
• "ABCD1234": The string you're searching for.
• ABC.txt: The file in which to search.

This command will output the line containing "ABCD1234" along with 2 lines before and 2 lines after it.

ChatGPT

Output from ChatGPT

You can use the grep command with the -C (or --context) option to show the matching line along with surrounding lines. Here’s the command:

sh grep -C 2 "ABCD1234" ABC.txt

Explanation:

• grep searches for the string "ABCD1234" in the file ABC.txt.
• -C 2 (or --context=2) displays 2 lines before and 2 lines after the matching line.

If you want more control, you can also use awk:

sh awk '/ABCD1234/ {for(i=-2;i<=2;i++) if (NR+i in lines) print lines[NR+i]} {lines[NR]=$0}' ABC.txt

This method allows flexibility in adjusting the number of lines dynamically.

Google

Search results did not show correct answer.