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System Commands · Most repeated questions

53 questions · 229 marks · 6 papers · 24 question types

Answer key

Indian Institute of Technology Madras

BS Degree Programme · Examination & Study Paper

System Commands

Most repeated questions

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.

Type 1 · asked 4 times · Scheduling jobs with cron

Interpret a crontab entry: when or how often the job runs

Q1MCQ4 Marks·Choose one option
End Term · 22 Dec 2024 (AN)Key ↓
1. AEvery Monday at 02:30 in June
2. BEvery Tuesday at 02:30 in June
3. CEvery Monday at 06:30 in June
4. DEvery Tuesday at 06:30 in July
Q2MCQ4 Marks·Choose one option
End Term · 22 Dec 2024 (FN)Key ↓
1. AEvery 15th of October at 23:45
2. BEvery 15th of November at 23:45
3. CEvery day at 23:45 in October
4. DEvery day at 15:45 in October
Q3NAT5 Marks·Write the number
End Term · 31 Aug 2025 (AN)Key ↓
Your answer:
Q4MSQ5 Marks·Choose all correct options
End Term · 31 Aug 2025 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 2 · asked 3 times · awk, sort & text filters

Predict output of sort on keys piped to awk that drops duplicate keys

Q5MCQ3 Marks·Choose one option
End Term · 22 Dec 2024 (AN)Key ↓
1. A
2. B
3. C
4. D
Q6MCQ3 Marks·Choose one option
End Term · 22 Dec 2024 (FN)Key ↓
1. A
2. B
3. C
4. D
Q7MCQ7 Marks·Choose one option
End Term · 13 Apr 2025 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 3 · asked 3 times · awk, sort & text filters

Choose commands that print a given range of lines from a file

Q8MSQ3 Marks·Choose all correct options
End Term · 22 Dec 2024 (AN)Key ↓
1. A
2. B
3. C
4. D
Q9MSQ3 Marks·Choose all correct options
End Term · 22 Dec 2024 (FN)Key ↓
1. A
2. B
3. C
4. D
Q10MSQ5 Marks·Choose all correct options
End Term · 31 Aug 2025 (AN)Key ↓
1. Ased -n '1,10p' file.txt
2. Bsed 11q file.txt
3. Cawk 'NR <= 10' file.txt
4. Dcat -n 10 file.txt

Type 4 · asked 3 times · Shell expansion, pipes & redirection

Count matching lines from grep piped to wc -l

Q11MCQ5 Marks·Choose one option
End Term · 31 Aug 2025 (FN)Key ↓
1. A
2. B
3. C
4. D
Q12NAT5 Marks·Write the number
End Term · 31 Aug 2025 (FN)Key ↓
Your answer:
Q13NAT4 Marks·Write the number
Quiz 1 · 26 Oct 2025 (AN)Key ↓
Your answer:

Type 5 · asked 2 times · Shell expansion, pipes & redirection

Predict the output of echo with nested brace expansion

Q14MCQ3 Marks·Choose one option
End Term · 22 Dec 2024 (AN)Key ↓
1. A
2. B
3. C
4. D
5. E
Q15MCQ3 Marks·Choose one option
End Term · 22 Dec 2024 (FN)Key ↓
1. A
2. B
3. C
4. D
5. E

Type 6 · asked 2 times · Regular expressions & grep

Choose the ERE pattern that matches lines with given field formats

Q16MCQ3 Marks·Choose one option
End Term · 22 Dec 2024 (AN)Key ↓
1. A
2. B
3. C
4. D
Q17MCQ3 Marks·Choose one option
End Term · 22 Dec 2024 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 7 · asked 2 times · Regular expressions & grep

Choose a regex that matches an address format (MAC or IPv4)

Q18MSQ3 Marks·Choose all correct options
End Term · 22 Dec 2024 (AN)Key ↓
1. A
2. B
3. C
4. D
Q19MSQ3 Marks·Choose all correct options
End Term · 22 Dec 2024 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 8 · asked 2 times · Regular expressions & grep

Palindrome strings with BRE backreferences

Q20MSQ4 Marks·Choose all correct options
End Term · 22 Dec 2024 (AN)Key ↓
1. A12321
2. B12345
3. CA1B1A
4. D9zXz9
5. EA1BA1
6. FARIRA
Q21MCQ4 Marks·Choose one option
End Term · 22 Dec 2024 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 9 · asked 2 times · awk, sort & text filters

Remove duplicate lines by the first three fields, keep first one

Q22MSQ3 Marks·Choose all correct options
End Term · 22 Dec 2024 (AN)Key ↓
1. A
2. B
3. C
4. D
Q23MSQ3 Marks·Choose all correct options
End Term · 22 Dec 2024 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 10 · asked 2 times · Finding files: find & wildcards

Find file/directory names that start with a and end with e

Q24MSQ3 Marks·Choose all correct options
End Term · 22 Dec 2024 (AN)Key ↓
1. A
2. B
3. C
4. D
Q25MCQ3 Marks·Choose one option
End Term · 22 Dec 2024 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 11 · asked 2 times · Bash scripting: logic, loops, functions

Which inputs make the leap-year script echo false or exit 1

Q26MSQ4 Marks·Choose all correct options
End Term · 22 Dec 2024 (AN)Key ↓
1. A
2. B
3. C
4. D
5. E
6. F
Q27MSQ4 Marks·Choose all correct options
End Term · 22 Dec 2024 (FN)Key ↓
1. A
2. B
3. C
4. D
5. E
6. F

Type 12 · asked 2 times · Bash scripting: logic, loops, functions

Trace a sed/tr script that builds an acronym from an argument

Q28Short answer3 Marks·Write the answer
End Term · 22 Dec 2024 (AN)Key ↓
NOTE: Enter the exact answer without any extra space in the beginning or at the end.
Your answer:
Q29Short answer4 Marks·Write the answer
End Term · 22 Dec 2024 (FN)Key ↓
NOTE:Enter the exact answer without any space in the beginning or at the end.
Your answer:

Type 13 · asked 2 times · Bash scripting: logic, loops, functions

Count characters printed by a function called in a foreground loop

Q30NAT4 Marks·Write the number
End Term · 22 Dec 2024 (AN)Key ↓
Your answer:
Q31NAT3 Marks·Write the number
End Term · 22 Dec 2024 (FN)Key ↓
Your answer:

Type 14 · asked 2 times · Bash scripting: logic, loops, functions

Count characters printed when a function runs in the background (&)

Q32NAT4 Marks·Write the number
End Term · 22 Dec 2024 (AN)Key ↓
Your answer:
Q33NAT4 Marks·Write the number
End Term · 22 Dec 2024 (FN)Key ↓
Your answer:

Type 15 · asked 2 times · awk, sort & text filters

Count items with an awk associative array (word or IP frequency)

Q34MCQ7 Marks·Choose one option
End Term · 13 Apr 2025 (FN)Key ↓
What is the primary purpose of this AWK script?
1. ATo convert contents of file to lowercase.
2. BTo count the frequency of each word in a text file.
3. CTo count the number of lines in a file.
4. DTo replace all non-alphabetic characters in a file.
Q35MCQ5 Marks·Choose one option
End Term · 31 Aug 2025 (AN)Key ↓
1. A192.168.0.1 3
2. B192.168.0.2 2
3. C192.168.0.3 1
4. DBoth 192.168.0.1 3 and 192.168.0.2 2

Type 16 · asked 2 times · Editing streams with sed

Swap two fields or words with sed backreferences

Q36MCQ6 Marks·Choose one option
End Term · 13 Apr 2025 (FN)Key ↓
1. ADeletes the first two fields in the CSV file.
2. BSwaps the first and second fields of the CSV file.
3. CAdds a new field to the CSV file.
4. DReplaces all commas in the CSV file with spaces.
Q37MSQ5 Marks·Choose all correct options
End Term · 31 Aug 2025 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 17 · asked 2 times · Finding files: find & wildcards

What does find ... -exec ... do

Q38MCQ7 Marks·Choose one option
End Term · 13 Apr 2025 (FN)Key ↓
1. ADeletes all .log files in /home.
2. BLists all .log files in /sample/logs.
3. CFinds all .log files and backs them up.
4. DRenames .log files to .bak in /home.
Q39MCQ5 Marks·Choose one option
End Term · 31 Aug 2025 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 18 · asked 2 times · Files, links, permissions & archives

What does tar with --exclude and -czf do

Q40MCQ6 Marks·Choose one option
End Term · 13 Apr 2025 (FN)Key ↓
1. ACompresses the /remove directory into a tarball, excluding the /sample subdirectory, and names it backup.tar.gz.
2. BDeletes the /sample subdirectory before creating a compressed tarball of /remove.
3. CExtracts the contents of backup.tar.gz to /remove, excluding the /sample directory.
4. DLists the contents of /remove, ignoring the /sample subdirectory.
Q41MCQ5 Marks·Choose one option
End Term · 31 Aug 2025 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 19 · asked 2 times · Files, links, permissions & archives

Count the entries extracted by tar -xzf from a described archive

Q42NAT5 Marks·Write the number
End Term · 31 Aug 2025 (AN)Key ↓
Your answer:
Q43NAT5 Marks·Write the number
End Term · 31 Aug 2025 (FN)Key ↓
Your answer:

Type 20 · asked 2 times · Networking, packages & admin tools

Order the commands to troubleshoot a network or web service

Q44MCQ5 Marks·Choose one option
End Term · 31 Aug 2025 (AN)Key ↓
1. A
2. B
3. C
4. D
Q45MCQ5 Marks·Choose one option
End Term · 31 Aug 2025 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 21 · asked 2 times · Text editors: vi, nano, ed, emacs

Match editors (vi, nano, ed, emacs) with commands or use cases

Q46MCQ5 Marks·Choose one option
End Term · 31 Aug 2025 (AN)Key ↓
1. A
2. B
3. C
4. D
Q47MCQ5 Marks·Choose one option
End Term · 31 Aug 2025 (FN)Key ↓
1. A
2. B
3. C
4. D

Type 22 · asked 2 times · Networking, packages & admin tools

Choose a command to show open or listening network ports

Q48MCQ6 Marks·Choose one option
End Term · 13 Apr 2025 (FN)Key ↓
Select a command to find all established suspicious TCP connections on port 80 using netstat
1. A
2. B
3. C
4. D
Q49MCQ3 Marks·Choose one option
Quiz 1 · 26 Oct 2025 (AN)Key ↓
Which command will give information on open network ports on the machine?
1. A
2. B
3. C
4. D

Type 23 · asked 2 times · Text editors: vi, nano, ed, emacs

Replace a word with the vi substitute command

Q50MCQ6 Marks·Choose one option
End Term · 13 Apr 2025 (FN)Key ↓
Which of the following vi command is used to replace the word 'apple' with 'orange' only in lines 10 to 20 of a file, and appear at the beginning or end of the line, without case sensitive and without user interaction.
1. A
2. B
3. C
4. D
Q51MCQ3 Marks·Choose one option
Quiz 1 · 26 Oct 2025 (AN)Key ↓
1. A
2. B
3. C
4. D

Type 24 · asked 2 times · Shell expansion, pipes & redirection

Subshells and the value of BASH_SUBSHELL

Q52NAT6 Marks·Write the number
End Term · 13 Apr 2025 (FN)Key ↓
Your answer:
Q53MSQ5 Marks·Choose all correct options
End Term · 31 Aug 2025 (AN)Key ↓
Which of the following statements about subshells is/are true?
1. A(cd /tmp; ls) runs in a subshell
2. Bcd /tmp; ls runs in a subshell
3. CVariables set in a subshell are visible to the parent shell
4. DCommands inside $(...) are executed in a subshell

Official Key

Master Answer Key & Explanations

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

Reveal Key

Q1B

Q2A

Q3120

Q4A, B, D

Q5B

Q6B

Q7B

Q8A, C, D

Q9A, D

Q10A, B, C

Q11B

Q124

Q135

Q14B

Q15A

Q16A

Q17A

Q18A, B

Q19A, B, D

Q20A, C, D, F

Q21B

Q22A, B, D

Q23A, B, D

Q24C

Q25C

Q26B, C, D, F

Q27B, C, D, F

Q28LAA

Q29HWFS

Q306

Q316

Q324

Q339

Q34B

Q35A

Q36B

Q37A, B, C, D

Q38C

Q39A

Q40A

Q41A

Q4225

Q4332

Q44C

Q45A

Q46D

Q47D

Q48B

Q49A

Q50D

Q51B

Q523

Q53A, D

Detailed Answer Notes & Working

Q28Answer: LAA: Case-sensitive: the answer must match exactly.
Q29Answer: HWFS: Case-sensitive: the answer must match exactly.

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.