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System Commands · Regular expressions & grep

16 questions · 64 marks · 6 papers

Answer key

Indian Institute of Technology Madras

BS Degree Programme · Examination & Study Paper

System Commands

Regular expressions & grep

Official Paper

Examination Instructions & Guidelines

Solve on notebook/paper first before checking solutions.
MCQ: Exactly 1 option is correct. Negative marking applies.
MSQ: One or more options correct. Select all to score.
NAT: Numerical response. No negative marking.
Scientific calculator allowed for all calculations.
Official answer key is sealed at the end of this sheet.

Quiz 1 · 26 Oct 2025 (AN)Quiz 1

Q1MCQ3 Marks·Choose one option
Key ↓
1. ALines starting with 3 letters and containing 2 digits anywhere.
2. BLines containing exactly 3 letters followed by exactly 2 digits.
3. CLines ending with 2 digits.
4. DAny line containing at least 3 letters and 2 digits.
Q2MCQ3 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
Q3MSQ3 Marks·Choose all correct options
Key ↓
1. A
2. B
3. C
4. D
Q4NAT4 Marks·Write the number
Asked 3 times Key ↓
Your answer:

End Term · 31 Aug 2025 (FN)End Term

Q5MCQ5 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
Q6NAT5 Marks·Write the number
Asked 3 times Key ↓
Your answer:

End Term · 31 Aug 2025 (AN)End Term

Q7MCQ5 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D
Q8MCQ5 Marks·Choose one option
Key ↓
A file numbers.txt contains several lines of numeric strings. You want to find lines where any digit is repeated exactly twice consecutively (like "1123", "4456"). Which command works correctly?
1. A
2. B
3. C
4. D
Q9MSQ5 Marks·Choose all correct options
Key ↓
Below is the man page of `grep`. Which of the following commands will print only the name of all .txt files that do not contain the word "error"? Assume the current directory does not have any subdirectories. Assume the filenames are alphanumeric.
1. Agrep -L "error" *.txt
2. Bgrep -v "error" *.txt
3. Cgrep -L "error" -- *.txt
4. Dfind . -name "*.txt" | xargs grep -L "error"

End Term · 13 Apr 2025 (FN)End Term

Q10MCQ6 Marks·Choose one option
Key ↓
1. A
2. B
3. C
4. D

End Term · 22 Dec 2024 (FN)End Term

Q11MCQ3 Marks·Choose one option
Asked 2 times Key ↓
1. A
2. B
3. C
4. D
Q12MCQ4 Marks·Choose one option
Asked 2 times Key ↓
1. A
2. B
3. C
4. D
Q13MSQ3 Marks·Choose all correct options
Asked 2 times Key ↓
1. A
2. B
3. C
4. D

End Term · 22 Dec 2024 (AN)End Term

Q14MCQ3 Marks·Choose one option
Asked 2 times Key ↓
1. A
2. B
3. C
4. D
Q15MSQ3 Marks·Choose all correct options
Asked 2 times Key ↓
1. A
2. B
3. C
4. D
Q16MSQ4 Marks·Choose all correct options
Asked 2 times Key ↓
1. A12321
2. B12345
3. CA1B1A
4. D9zXz9
5. EA1BA1
6. FARIRA

Official Key

Master Answer Key & Explanations

Official answer keys from IIT Madras BS past papers. Click any question to review.

Reveal Key

Q1B

Q2B

Q3A, D

Q45

Q5B

Q64

Q7C

Q8A

Q9A, C, D

Q10D

Q11A

Q12B

Q13A, B, D

Q14A

Q15A, B

Q16A, C, D, F

Questions and answer keys are reproduced from the official IIT Madras BS papers. Topics and repeated question types are BTechi’s own grouping. BTechi is not affiliated with IIT Madras.