set -e for exit on error in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output when using set -e with a failing command?

Consider this bash script:

#!/bin/bash
set -e
echo "Start"
false
echo "End"

What will be printed when this script runs?

Bash Scripting

#!/bin/bash
set -e
echo "Start"
false
echo "End"

A Start

B

Start
End

C End

D No output

💡 Hint

Remember, set -e stops the script if any command fails.

The script prints "Start" then runs the command 'false' which returns an error. Because of 'set -e', the script exits immediately and does not print "End".

💻 Command Output

intermediate

How does set -e behave inside a function?

Given this script:

#!/bin/bash
set -e
function test_func() {
  echo "Inside function"
  false
  echo "After false"
}

echo "Before function"
test_func
echo "After function"

What will be the output?

Bash Scripting

#!/bin/bash
set -e
function test_func() {
  echo "Inside function"
  false
  echo "After false"
}

echo "Before function"
test_func
echo "After function"

A

Before function
Inside function
After function

B

Before function
Inside function

C

Before function
Inside function
After false
After function

D

Inside function
After false
After function

💡 Hint

set -e exits the whole script if any command fails, even inside functions.

The script prints "Before function" then calls test_func which prints "Inside function". The 'false' command fails, so due to 'set -e', the script exits immediately. "After false" and "After function" are not printed.

🔧 Debug

advanced

Why does set -e not exit on a failing command in a pipeline?

Look at this script:

#!/bin/bash
set -e
false | true
echo "Still running"

Why does it print "Still running" even though 'false' fails?

Bash Scripting

#!/bin/bash
set -e
false | true
echo "Still running"

A Because only the last command's exit status in a pipeline affects set -e

B Because set -e is disabled inside pipelines

C Because 'true' overrides the failure of 'false' in set -e

D Because set -e ignores failures in all pipelines

💡 Hint

Check which command's exit status is checked in a pipeline with set -e.

In bash, with set -e, only the exit status of the last command in a pipeline is considered. Here, 'true' is last and succeeds, so the script continues.

📝 Syntax

advanced

Which script correctly uses set -e to stop on errors and handle a failing command in a pipeline?

You want the script to exit if any command fails, including in pipelines. Which script does this correctly?

A

#!/bin/bash
set -e
set +o pipefail
false | true
echo "Done"

B

#!/bin/bash
set -eo pipefail
false | true
echo "Done"

C

#!/bin/bash
set -e
false | true
echo "Done"

D

#!/bin/bash
set -e
set -o pipefail
false | true
echo "Done"

💡 Hint

Look for the option that enables pipefail with set -e.

To make set -e exit on any failing command in a pipeline, you must enable 'pipefail'. Option D correctly sets both 'set -e' and 'set -o pipefail'.

🚀 Application

expert

How to safely run multiple commands with set -e and ignore errors in one command?

You want a script that stops on any error except for one command that might fail but should not stop the script. Which snippet does this correctly?

A

#!/bin/bash
set -e
command1
set +e
command2
set -e
command3

B

#!/bin/bash
set -e
command1
if ! command2; then echo "Ignore error"; fi
command3

C

#!/bin/bash
set -e
command1
command2 || true
command3

D

#!/bin/bash
set -e
command1
command2
command3

💡 Hint

Use a way to ignore error from one command without disabling set -e globally.

Option C uses 'command2 || true' which makes the command always succeed, so set -e does not exit. This is a common pattern to ignore errors from a single command while keeping set -e active.