System Commands, OPPE 2

January 2026 term, Set A

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Question 1

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Given a list of filenames (with extensions), one per line, write a script that prints the unique file extensions, sorted alphabetically.

Instructions

• Write your script in script.sh.
• Read input from standard input.
• Extensions are case-insensitive; output in lowercase with a leading dot.
• Output should be sorted alphabetically and contain unique extensions only.

Sample Input

hello.txt
bye.pdf
cats.txt
video.mp4
music.mp3
document.docx
list.txt
song.mp3
movie.MP4

Sample Output

.docx
.mp3
.mp4
.pdf
.txt

Constraints

• Filenames always contain at least one dot.
• Extensions may be in any case; output must be lowercase.

Code Editor

Bash

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#!/usr/bin/env bash
# Write your script here

#!/usr/bin/env bash # Write your script here

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Given a list of filenames (with extensions), one per line, write a script that prints the unique file extensions, sorted alphabetically. ## Instructions - Write your script in script.sh. - Read input from standard input. - Extensions are case-insensitive; output in lowercase with a leading dot. - Output should be sorted alphabetically and contain unique extensions only. ## Sample Input ```text hello.txt bye.pdf cats.txt video.mp4 music.mp3 document.docx list.txt song.mp3 movie.MP4 ``` ## Sample Output ```text .docx .mp3 .mp4 .pdf .txt ``` ## Constraints - Filenames always contain at least one dot. - Extensions may be in any case; output must be lowercase. Given a number n, determine if it is a prime number. ## Instructions - Write your script in script.sh. - Read an integer n from standard input. - Print "Prime" if n is a prime number, or "Not Prime" if it is not. - The script should be executable by your user. ## Sample Input ```text 5 ``` ## Sample Output ```text Prime ``` ## Constraints - 1 <= n <= 10^6 You receive a message encoded multiple times with base64. Decode it iteratively; stop when the decoded text contains a non-base64 character (the original message always does). Print the iteration number and decoded text for each step. ## Instructions - Write your script in script.sh. - Read the encoded message from standard input. - For each iteration print: N: decoded_text - Stop when the decoded text contains a non-base64 character. ## Sample Input ```text WVVjNU0wbEhSbmxhVTBJMVlqTlZMME5uUFQwSwo= ``` ## Sample Output ```text 1: YUc5M0lHRnlaU0I1YjNVL0NnPT0K 2: aG93IGFyZSB5b3U/Cg== 3: how are you? ``` ## Constraints - The original message is guaranteed to contain a non-base64 character. - Non-base64 characters are anything outside [A-Za-z0-9+/=].