Progress indicators in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this progress indicator script?

Consider this bash script snippet that simulates a progress bar:

for i in {1..5}; do
  echo -n "."
  sleep 1
done
echo " Done!"

What will be the output after running this script?

Bash Scripting

for i in {1..5}; do
  echo -n "."
  sleep 1
done
echo " Done!"

A ..... Done!

B . . . . . Done!

C Error: sleep command not found

D .....\nDone!

💡 Hint

Look at how echo -n works and how the loop prints dots.

The loop prints a dot without a newline 5 times, then prints ' Done!' on the same line.

📝 Syntax

intermediate

Which option correctly implements a spinner progress indicator in bash?

You want to create a spinner that cycles through | / - \ characters in bash. Which of these code snippets correctly implements this spinner inside a loop?

Bash Scripting

spinner='|/-\\'
for i in {1..4}; do
  # print spinner character
  # wait 0.2 seconds
  # erase spinner character
  # move to next character
  sleep 0.2
done

A for i in {0..3}; do echo -ne "${spinner:i:1}"; sleep 0.2; echo -ne "\b"; done

B for i in {0..3}; do echo -n "${spinner:i:1}"; sleep 0.2; echo -n "\b"; done

C for i in {0..3}; do echo -n "${spinner:i:1}"; sleep 0.2; echo -ne "\r"; done

D for i in {0..3}; do echo -ne "${spinner:i:1}"; sleep 0.2; echo -ne "\r"; done

💡 Hint

Use echo -ne to print without newline and interpret backslash sequences.

Option A uses echo -ne to print spinner char and backspace \b to erase it, correctly cycling spinner.

🔧 Debug

advanced

Why does this progress bar script not update correctly?

This script is supposed to show a progress bar updating from 0% to 100%:

for i in $(seq 0 20 100); do
  echo -n "[${i}%]"
  sleep 1
done
echo

But it prints all progress states on separate lines instead of updating the same line. What is the main reason?

A seq command outputs numbers with newlines causing echo to fail

B echo -n does not prevent newline, so each print goes to new line

C sleep command causes line breaks after each print

D Missing carriage return \r to return cursor to line start before printing

💡 Hint

Think about how to overwrite the same line in terminal output.

Without \r, each echo prints after the previous, so progress bar does not overwrite previous output.

🚀 Application

advanced

Which script shows a progress bar with dynamic width based on terminal size?

You want a bash script that shows a progress bar filling from 0% to 100%, adjusting bar width to terminal width. Which script correctly calculates terminal width and updates the bar accordingly?

A

width=$(tput cols)
for i in $(seq 0 10 100); do
  filled=$(( i / width * 100 ))
  empty=$(( width - filled ))
  printf "[%0.s#" $(seq 1 $filled)
  printf "%0.s-" $(seq 1 $empty)
  printf "] %d%%\r" $i
  sleep 0.5
done
echo

B

width=$(tput cols)
for i in $(seq 0 10 100); do
  filled=$(( width * 100 / i ))
  empty=$(( width - filled ))
  printf "[%0.s#" $(seq 1 $filled)
  printf "%0.s-" $(seq 1 $empty)
  printf "] %d%%\r" $i
  sleep 0.5
done
echo

C

width=$(tput cols)
for i in $(seq 0 10 100); do
  filled=$(( i * width / 100 ))
  empty=$(( width - filled ))
  printf "[%0.s#" $(seq 1 $filled)
  printf "%0.s-" $(seq 1 $empty)
  printf "] %d%%\r" $i
  sleep 0.5
done
echo

D

width=$(tput cols)
for i in $(seq 0 10 100); do
  filled=$(( width - i ))
  empty=$(( i ))
  printf "[%0.s#" $(seq 1 $filled)
  printf "%0.s-" $(seq 1 $empty)
  printf "] %d%%\r" $i
  sleep 0.5
done
echo

💡 Hint

Calculate filled length as percentage of terminal width.

Option C correctly calculates filled bar length proportional to progress percent and terminal width.

🧠 Conceptual

expert

What is the main benefit of using \r (carriage return) in progress indicators?

In bash scripting, why is the carriage return character \r important when creating progress indicators?

A It clears the entire terminal screen before printing new output

B It moves the cursor to the beginning of the current line allowing overwriting previous output

C It moves the cursor to the next line to print progress on a new line

D It pauses the script execution until user input is received

💡 Hint

Think about how to update progress on the same line without clutter.

Carriage return \r moves cursor to line start so new output overwrites old output, enabling smooth progress updates.