Bash vs other shells (Zsh, Fish, sh) in Bash Scripting - Practice Questions

Challenge - 5 Problems

💻 Command Output

intermediate

Output difference: Bash vs Fish shell variable assignment

What is the output of the following commands when run in Bash and Fish shells respectively?

VAR=hello; echo $VAR

Bash Scripting

VAR=hello; echo $VAR

A hello\nhello

B hello\n$VAR

C $VAR\nhello

D $VAR\n$VAR

💡 Hint

Think about how variable assignment and expansion syntax differs between Bash and Fish.

In Bash, 'VAR=hello' assigns the variable and 'echo $VAR' prints 'hello'. In Fish, the same syntax works similarly for this simple case, so both print 'hello'.

💻 Command Output

intermediate

Which shell supports this array syntax?

Consider this code snippet:

arr=(one two three)
echo ${arr[1]}

Which shell will output two when running this?

Bash Scripting

arr=(one two three)
echo ${arr[1]}

A Bash

B sh

C Fish

D All shells

💡 Hint

Think about which shells support arrays and their indexing style.

Bash supports arrays with zero-based indexing and ${arr[1]} outputs 'two'. sh does not support arrays. Fish uses a different syntax for arrays.

📝 Syntax

advanced

Identify the syntax error in this Fish shell function

Which option shows the correct Fish shell function syntax to print 'Hello World'?

A

greet() {
  echo 'Hello World'
}

B

function greet() {
  echo 'Hello World'
}

C

def greet():
  echo 'Hello World'

D

function greet
  echo 'Hello World'
end

💡 Hint

Fish shell uses a unique function syntax different from Bash or sh.

Fish shell functions start with 'function name' and end with 'end'. Options A and D use Bash-style syntax. Option D is Python-like.

🔧 Debug

advanced

Why does this sh script fail but Bash runs it?

Given this script:

#!/bin/sh for i in {1..3}; do echo $i; done

Why does it fail in sh but work in Bash?

Bash Scripting

#!/bin/sh
for i in {1..3}; do echo $i; done

A sh does not support for loops, Bash does

B sh requires 'do' on the same line as 'for', Bash does not

C sh does not support brace expansion like {1..3}, Bash does

D sh needs 'echo "$i"' with quotes, Bash does not

💡 Hint

Check which shell features are supported by POSIX sh.

Brace expansion {1..3} is a Bash feature, not POSIX sh. sh treats it as a literal string, causing the loop to run once with '{1..3}'.

🚀 Application

expert

Automate environment setup: Which shell command sets a variable permanently?

You want to set an environment variable MY_VAR to 'value' permanently for your user.
Which command correctly adds this to your shell configuration for Bash, Zsh, and Fish respectively?

A echo 'set -x MY_VAR value' >> ~/.bashrc && echo 'set -x MY_VAR value' >> ~/.zshrc && echo 'export MY_VAR=value' >> ~/.config/fish/config.fish

B echo 'export MY_VAR=value' >> ~/.bashrc && echo 'export MY_VAR=value' >> ~/.zshrc && echo 'set -x MY_VAR value' >> ~/.config/fish/config.fish

C echo 'export MY_VAR=value' >> ~/.bash_profile && echo 'set -x MY_VAR value' >> ~/.zshrc && echo 'export MY_VAR=value' >> ~/.config/fish/config.fish

D echo 'set MY_VAR=value' >> ~/.bashrc && echo 'set MY_VAR=value' >> ~/.zshrc && echo 'set MY_VAR=value' >> ~/.config/fish/config.fish

💡 Hint

Remember the syntax for setting environment variables differs between Bash/Zsh and Fish.

Bash and Zsh use 'export VAR=value' in their rc files. Fish uses 'set -x VAR value' in its config.fish file to export variables.