Report generation script in Bash Scripting - Mini Project: Build & Apply

Report generation script

📖 Scenario: You work in an office where you need to create a simple report from sales data every day. The sales data is stored in a text file with product names and sales numbers. You want to automate making a report that shows only the products with sales above a certain number.

🎯 Goal: Build a bash script that reads sales data from a file, filters products with sales above a threshold, and prints a simple report.

📋 What You'll Learn

Create a sales data file with exact product names and sales numbers

Add a variable for the sales threshold

Use a loop to read the file and select products with sales above the threshold

Print the filtered report showing product names and sales

💡 Why This Matters

🌍 Real World

Automating daily report generation from sales or other data files saves time and reduces errors.

💼 Career

Many jobs require writing scripts to process data files and create reports automatically.

1

Create the sales data file

Create a file called sales.txt with these exact lines:
Apple 50
Banana 30
Cherry 20
Date 40
Elderberry 10

Bash Scripting

# Create the sales.txt file with the exact lines
# Your code here

Hint

Use echo -e with newline characters \n to write multiple lines to sales.txt.

2

Set the sales threshold

Add a variable called threshold and set it to 25.

Bash Scripting

echo -e "Apple 50\nBanana 30\nCherry 20\nDate 40\nElderberry 10" > sales.txt
# Set the sales threshold variable
# Your code here

Hint

Use threshold=25 to create the variable.

3

Filter products with sales above threshold

Use a while loop to read each line from sales.txt. Inside the loop, use if to check if the sales number is greater than threshold. If yes, add the product and sales to a variable called report with a newline after each entry.

Bash Scripting

echo -e "Apple 50\nBanana 30\nCherry 20\nDate 40\nElderberry 10" > sales.txt
threshold=25
report=""
# Use a while loop to read sales.txt and filter products
# Your code here

Hint

Use while read product sales; do ... done < sales.txt to read the file line by line.

Use if [ "$sales" -gt "$threshold" ] to compare numbers.

4

Print the filtered report

Print the report variable to show the products with sales above the threshold.

Bash Scripting

echo -e "Apple 50\nBanana 30\nCherry 20\nDate 40\nElderberry 10" > sales.txt
threshold=25
report=""
while read product sales; do
  if [ "$sales" -gt "$threshold" ]; then
    report+="$product $sales\n"
  fi
done < sales.txt
# Print the report variable
# Your code here

Hint

Use printf "%b" "$report" to print the variable with newlines correctly.

Practice

1. What is the main purpose of a report generation script in bash?

easy

A. To automatically collect and save information into a file

B. To compile source code into an executable

C. To delete all files in a directory

D. To open a graphical user interface

Solution

1. Step 1: Understand the script's goal

   A report generation script is designed to gather data and save it for review.

2. Step 2: Match purpose with options

   Only To automatically collect and save information into a file describes collecting and saving information automatically.

3. Final Answer:

   To automatically collect and save information into a file -> Option A

4. Quick Check:

   Report generation = collect and save info [OK]

Hint: Think: What does 'report generation' mean? Collect and save! [OK]

Common Mistakes:

• Confusing report generation with compiling code
• Thinking it deletes files
• Assuming it opens GUIs

2. Which line correctly starts a bash script for report generation?

easy

A. echo "Start script"

B. #!/bin/python

C. #!/bin/bash

D. import bash

Solution

1. Step 1: Identify the correct shebang for bash

   The first line in a bash script must be #!/bin/bash to specify the interpreter.

2. Step 2: Check other options

   Options B, C, and D are either for other languages or commands, not the script start line.

3. Final Answer:

   #!/bin/bash -> Option C

4. Quick Check:

   Shebang for bash = #!/bin/bash [OK]

Hint: Always start bash scripts with #!/bin/bash [OK]

Common Mistakes:

• Using wrong interpreter path
• Starting with commands instead of shebang
• Confusing bash with python

3. What will be the output of this script?

#!/bin/bash

filename="report.txt"
echo "Report generated on: $(date)" > $filename
echo "User count: $(who | wc -l)" >> $filename
cat $filename

medium

A. Shows an error because of wrong variable usage

B. Prints current date and number of logged-in users in report.txt

C. Prints only the date, not user count

D. Creates an empty file named report.txt

Solution

1. Step 1: Analyze echo commands and redirection

   The first echo writes the date line to report.txt (overwrite). The second echo appends user count.

2. Step 2: Understand the final cat command

   cat prints the contents of report.txt, showing both lines.

3. Final Answer:

   Prints current date and number of logged-in users in report.txt -> Option B

4. Quick Check:

   echo > overwrite, echo >> append, cat prints file [OK]

Hint: Remember > overwrites, >> appends in bash [OK]

Common Mistakes:

• Confusing > and >> operators
• Thinking variable usage is wrong
• Assuming file is empty

4. Identify the error in this report generation script snippet:

#!/bin/bash
filename=report.txt
echo "Start report" > $filename
echo "Date: $(date)" > $filename
cat $filename

medium

A. The second echo overwrites the file, losing the first line

B. The variable filename is not defined correctly

C. Missing execute permission on the script

D. The cat command is incorrect

Solution

1. Step 1: Check file redirection operators

   The first echo writes "Start report" to the file. The second echo uses > again, overwriting the file.

2. Step 2: Understand the effect on output

   Because of overwrite, the first line is lost. Only the date line remains in the file.

3. Final Answer:

   The second echo overwrites the file, losing the first line -> Option A

4. Quick Check:

   Using > twice overwrites file [OK]

Hint: Use >> to append, not > to avoid overwriting [OK]

Common Mistakes:

• Assuming > appends instead of overwriting
• Thinking variable is undefined
• Blaming cat command

5. You want to create a report script that lists all files in the current directory and their sizes, saving to files_report.txt. Which script snippet correctly does this?

hard

A. #!/bin/bash
ls -l > files_report.txt

B. #!/bin/bash
ls -l >> files_report.txt
ls -a > files_report.txt

C. #!/bin/bash
ls -lh > files_report.txt

D. #!/bin/bash
ls -lh > files_report.txt
wc -l >> files_report.txt

Solution

1. Step 1: Understand the requirements

   The report must list files with sizes and save to files_report.txt.

2. Step 2: Analyze options for correct commands and output

   #!/bin/bash ls -lh > files_report.txt wc -l >> files_report.txt uses ls -lh for human-readable sizes and writes to the file. Then it appends the line count with wc -l, adding useful info.

3. Step 3: Check other options

   #!/bin/bash ls -l > files_report.txt lacks human-readable sizes. #!/bin/bash ls -l >> files_report.txt ls -a > files_report.txt overwrites file after appending, losing data. #!/bin/bash ls -lh > files_report.txt misses line count info.

4. Final Answer:

   Option D correctly lists files with sizes and appends line count to the report -> Option D

5. Quick Check:

   ls -lh for sizes + wc -l appended = correct report [OK]

Hint: Use ls -lh for sizes and append extra info with >> [OK]

Common Mistakes:

• Overwriting file after appending
• Not using human-readable size option
• Missing extra useful info like line count