Linux Practical Set D Solution – File Operations & Text Processing

In this article, we will solve VNSGU TYBCA Semester 5 Linux (UNIX) Practical – Set D using shell scripting.

This practical focuses on basic file handling and text-processing commands such as:

• cat
• head
• tail
• wc
• grep

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📌 Practical Question

Write a shell script to perform following:

1. Create a file named marks.txt and insert 5 lines of text.
2. Display the first 3 lines of marks.txt.
3. Display the last 2 lines of marks.txt.
4. Count the number of words, lines, and characters in marks.txt.
5. Search for the word Linux in marks.txt.

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🧠 Commands Used

Command	Purpose
cat	Create and display file content
head	Display the beginning of a file
tail	Display the end of a file
wc	Count lines, words, and characters
grep	Search for text

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✅ Solution 1: Using read, head, tail, wc and grep

This solution takes 5 lines interactively from the user and stores them in marks.txt.

Shell Script

#!/bin/bash

echo "Enter 5 lines of text:"

> marks.txt

for ((i=1; i<=5; i++))
do
    read -p "Enter line $i: " line
    echo "$line" >> marks.txt
done

echo
echo "----- First 3 Lines -----"
head -n 3 marks.txt

echo
echo "----- Last 2 Lines -----"
tail -n 2 marks.txt

echo
echo "----- File Statistics -----"
echo "Lines      : $(wc -l < marks.txt)"
echo "Words      : $(wc -w < marks.txt)"
echo "Characters : $(wc -m < marks.txt)"

echo
echo "----- Searching for Linux -----"
grep "Linux" marks.txt

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🔍 Step-by-Step Explanation

Step 1: Create or Empty the File

> marks.txt

This creates marks.txt if it does not exist.

If the file already exists, its previous content is removed.

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Step 2: Take 5 Lines from the User

for ((i=1; i<=5; i++))
do
    read -p "Enter line $i: " line
    echo "$line" >> marks.txt
done

The loop runs exactly 5 times.

For example:

Enter line 1: Linux is an operating system
Enter line 2: Linux supports shell scripting
Enter line 3: Shell commands are useful
Enter line 4: Unix and Linux are related
Enter line 5: Linux is widely used

Each line is appended to marks.txt.

The >> operator is used to append content to the file.

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Step 3: Display First 3 Lines

head -n 3 marks.txt

The head command displays the beginning of a file.

Here:

-n 3

means:

Display the first 3 lines.

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Step 4: Display Last 2 Lines

tail -n 2 marks.txt

The tail command displays the end of a file.

Here:

-n 2

means:

Display the last 2 lines.

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Step 5: Count Lines

wc -l < marks.txt

The -l option counts the number of lines.

For our five-line file:

5

The < redirects the file content to wc, so only the number is displayed.

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Step 6: Count Words

wc -w < marks.txt

The -w option counts the number of words in the file.

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Step 7: Count Characters

wc -m < marks.txt

The -m option counts the number of characters.

This is preferable to plain wc when the question specifically asks for characters.

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Step 8: Search for Linux

grep "Linux" marks.txt

The grep command searches for the word or pattern Linux.

It displays every line containing Linux.

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🖥️ Sample Output

Enter 5 lines of text:
Enter line 1: Linux is an operating system
Enter line 2: Linux supports shell scripting
Enter line 3: Shell commands are useful
Enter line 4: Unix and Linux are related
Enter line 5: Linux is widely used

----- First 3 Lines -----
Linux is an operating system
Linux supports shell scripting
Shell commands are useful

----- Last 2 Lines -----
Unix and Linux are related
Linux is widely used

----- File Statistics -----
Lines      : 5
Words      : 24
Characters : 142

----- Searching for Linux -----
Linux is an operating system
Linux supports shell scripting
Unix and Linux are related
Linux is widely used

The exact word and character counts will depend on the text entered by the user.

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🔄 Solution 2: Using cat to Insert 5 Lines

The question can also be solved using cat.

#!/bin/bash

echo "Enter 5 lines of text:"

cat > marks.txt

echo
echo "----- First 3 Lines -----"
head -n 3 marks.txt

echo
echo "----- Last 2 Lines -----"
tail -n 2 marks.txt

echo
echo "----- File Statistics -----"
echo "Lines      : $(wc -l < marks.txt)"
echo "Words      : $(wc -w < marks.txt)"
echo "Characters : $(wc -m < marks.txt)"

echo
echo "----- Searching for Linux -----"
grep "Linux" marks.txt

After entering the five lines, press:

Ctrl + D

to finish the input.

Which Method Is Better?

For beginners, Solution 1 is easier to understand because it clearly shows the five iterations of the loop.

The cat method is shorter and demonstrates interactive file creation using cat.

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🔄 Solution 3: Automatically Create the File Using Here Document

If you don't want the user to enter the five lines manually, you can use a here document.

#!/bin/bash

cat > marks.txt << EOF
Linux is an operating system
Linux supports shell scripting
Shell commands are useful
Unix and Linux are related
Linux is widely used
EOF

echo "----- First 3 Lines -----"
head -n 3 marks.txt

echo
echo "----- Last 2 Lines -----"
tail -n 2 marks.txt

echo
echo "----- File Statistics -----"
echo "Lines      : $(wc -l < marks.txt)"
echo "Words      : $(wc -w < marks.txt)"
echo "Characters : $(wc -m < marks.txt)"

echo
echo "----- Searching for Linux -----"
grep "Linux" marks.txt

Here:

<< EOF

allows multiple lines of text to be provided as input to the command.

The EOF at the end marks the end of the input.

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🔍 Searching for Linux Case-Insensitively

By default:

grep "Linux" marks.txt

is case-sensitive.

Therefore, these are treated differently:

Linux
linux
LINUX

If the search should ignore uppercase/lowercase differences, use:

grep -i "Linux" marks.txt

The -i option makes the search case-insensitive.

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🔄 Alternative: Using sed

Although head and tail are the simplest commands for this question, sed can also be used.

First 3 Lines

sed -n '1,3p' marks.txt

Here:

• -n → Suppresses automatic output
• 1,3 → Lines 1 to 3
• p → Print

Last 2 Lines

We can calculate the total number of lines first:

total=$(wc -l < marks.txt)
start=$((total - 1))

sed -n "${start},${total}p" marks.txt

However, for this practical, head and tail are simpler and easier to remember.

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📊 Important Commands at a Glance

Requirement	Command
Create/empty file	> marks.txt
Append text	echo "text" >> marks.txt
First 3 lines	head -n 3 marks.txt
Last 2 lines	tail -n 2 marks.txt
Count lines	wc -l marks.txt
Count words	wc -w marks.txt
Count characters	wc -m marks.txt
Search Linux	grep "Linux" marks.txt
Case-insensitive search	grep -i "Linux" marks.txt

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🧠 Why Use wc -m for Characters?

A common mistake is to use:

wc marks.txt

and assume that the third value is the character count.

By default, wc generally displays:

lines words bytes

Therefore, when the question specifically asks for characters, use:

wc -m marks.txt

This makes the intention of the script clear.

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⚠️ Common Mistakes

Mistake 1: Using > Instead of >>

This:

echo "$line" > marks.txt

overwrites the file every time.

Therefore, after the loop only the last line would remain.

Use:

echo "$line" >> marks.txt

to append each line.

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Mistake 2: Using wc for Character Count

Instead of:

wc marks.txt

use:

wc -m marks.txt

when you specifically need the character count.

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Mistake 3: Forgetting Case Sensitivity

This:

grep "Linux" marks.txt

does not necessarily match:

linux
LINUX

Use:

grep -i "Linux" marks.txt

when a case-insensitive search is required.

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🎯 Practical Exam Tips

Remember these commands:

head -n 3 marks.txt

→ First 3 lines

tail -n 2 marks.txt

→ Last 2 lines

wc -l marks.txt

→ Number of lines

wc -w marks.txt

→ Number of words

wc -m marks.txt

→ Number of characters

grep "Linux" marks.txt

→ Search for Linux

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📚 Related Linux Practical Sets

This solution is part of the VNSGU TYBCA Sem 5 Linux (UNIX) Practical – OCT/Nov 2025 solution series.

• Set A – Simple Interest & Compound Interest
• Set B – Vowels Count & Case Conversion
• Set C – Palindrome String
• Set D – File Operations & Text Processing
• Set E – Display Lines with Validation
• Set F – Count Files & Directories
• Set G – Recently Modified Files
• Set H – Employee Gross Salary

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🐧 Conclusion

Set D is an important Linux practical because it combines several commonly used file and text-processing commands in one shell script.

The main commands to remember are:

cat   → File creation/input
head  → Beginning of file
tail  → End of file
wc    → Counting
grep  → Searching

Practice these commands individually first and then combine them into the complete shell script.

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💬 What Do You Prefer?

For displaying specific lines from a file, which approach do you prefer?

head / tail or sed?

Share your approach in the comments! 🐧💻

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📌 Tags

linux shell unix beginners