Installing Deno - Practice Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the correct command to install Deno using PowerShell on Windows?

You want to install Deno on a Windows machine using PowerShell. Which command should you run?

A apt-get install deno

B curl -fsSL https://deno.land/install.sh | sh

C brew install deno

D iwr https://deno.land/install.ps1 -useb | iex

💡 Hint

PowerShell uses 'iwr' (Invoke-WebRequest) and 'iex' (Invoke-Expression) for scripts.

On Windows PowerShell, the official Deno install command uses iwr and iex to download and run the install script.

Option D is for Unix shells, C is for macOS Homebrew, and D is for Linux package managers but not the official method.

🧠 Conceptual

intermediate

Which command installs Deno on macOS using Homebrew?

You have a Mac and want to install Deno using Homebrew. Which command is correct?

A choco install deno

B brew install deno

C apt install deno

D curl -fsSL https://deno.land/install.ps1 | sh

💡 Hint

Homebrew is the package manager for macOS.

Homebrew uses the brew install command to install packages like Deno.

Option B is for Windows Chocolatey, B is for Linux apt, and D is a PowerShell script which is not for macOS.

📝 Syntax

advanced

What error will this Deno install command cause on Linux?

You run this command on Linux terminal: iwr https://deno.land/install.ps1 -useb | iex. What happens?

Deno

iwr https://deno.land/install.ps1 -useb | iex

A Command not found error for 'iwr'

B Runs successfully and installs Deno

C Permission denied error

D SyntaxError: command not found

💡 Hint

The command uses PowerShell-specific commands on Linux bash shell.

The iwr and iex commands are PowerShell commands and do not exist in Linux bash shell, so the shell reports 'command not found' for iwr.

❓ component_behavior

advanced

What happens after running the official Deno install script on Unix?

You run curl -fsSL https://deno.land/install.sh | sh on a Unix system. What is the expected result?

Deno

curl -fsSL https://deno.land/install.sh | sh

A Deno installs but the binary is not added to PATH

B Nothing happens because the script is empty

C Deno is downloaded and installed, and the binary is added to ~/.deno/bin

D The system crashes due to script errors

💡 Hint

The official script downloads Deno and sets up the binary location.

The install script downloads the Deno binary and places it in ~/.deno/bin. It also suggests adding this path to your shell PATH variable.

🔧 Debug

expert

Why does running deno command fail after installation?

You installed Deno using the official script on Linux, but typing deno in terminal says 'command not found'. What is the most likely cause?

A The ~/.deno/bin directory is not added to the PATH environment variable

B Deno was not downloaded due to network failure

C The shell does not support running binaries

D Deno requires root permissions to run

💡 Hint

Check if the directory with the Deno binary is in your PATH.

After installation, the Deno binary is placed in ~/.deno/bin. If this directory is not in your PATH, the shell cannot find the deno command.

Practice

1. What is the main command to check if Deno is installed correctly on your system?

easy

A. deno --version

B. deno install

C. deno start

D. deno run

Solution

1. Step 1: Understand the purpose of the command

   The command deno --version is used to check the installed version of Deno, confirming installation.

2. Step 2: Compare with other commands

   Other commands like deno install, deno start, and deno run are for running or installing scripts, not checking installation.

3. Final Answer:

   deno --version -> Option A

4. Quick Check:

   Check installation = deno --version [OK]

Hint: Use 'deno --version' to verify installation quickly [OK]

Common Mistakes:

• Trying to use 'deno install' to check installation
• Confusing 'deno run' with installation check
• Using 'deno start' which is not a valid command

2. Which of the following is the correct command to install Deno on Unix-like systems using the terminal?

easy

A. npm install -g deno

B. curl -fsSL https://deno.land/install.sh | sh

C. deno install https://deno.land/install.sh

D. wget https://deno.land/install.sh

Solution

1. Step 1: Identify the official installation method

   The official way to install Deno on Unix-like systems is to run the shell script via curl piped to sh.

2. Step 2: Evaluate other options

   npm install -g deno uses npm which is not used for Deno installation. deno install https://deno.land/install.sh is incorrect syntax. wget https://deno.land/install.sh downloads the script but does not execute it.

3. Final Answer:

   curl -fsSL https://deno.land/install.sh | sh -> Option B

4. Quick Check:

   Unix install = curl script | sh [OK]

Hint: Use curl with pipe to sh for Unix Deno install [OK]

Common Mistakes:

• Trying to install Deno with npm
• Downloading script without executing it
• Using incorrect command syntax

3. After running the installation script on Windows PowerShell, which command will show the installed Deno version if installation succeeded?

medium

A. deno --version

B. deno version

C. deno -v

D. deno check

Solution

1. Step 1: Recall the standard version check command

   The command deno --version is the official way to display the installed version.

2. Step 2: Understand why others are incorrect

   deno version and deno -v are not recognized commands. deno check checks code, not version.

3. Final Answer:

   deno --version -> Option A

4. Quick Check:

   Version command = deno --version [OK]

Hint: Use 'deno --version' to confirm installation on any OS [OK]

Common Mistakes:

• Using 'deno version' instead of 'deno --version'
• Trying 'deno -v' which is invalid
• Confusing 'deno check' with version command

4. You ran curl -fsSL https://deno.land/install.sh | sh on Linux but get a 'command not found' error for deno. What is the most likely cause?

medium

A. Deno is not supported on Linux

B. You need to restart your computer before using Deno

C. You must run the command as root user

D. The installation script did not add Deno to your PATH environment variable

Solution

1. Step 1: Understand the error meaning

   'command not found' means the shell cannot find the deno executable in the PATH.

2. Step 2: Identify common installation issue

   The script installs Deno but may not update PATH automatically, so the shell can't find it until PATH is updated.

3. Final Answer:

   The installation script did not add Deno to your PATH environment variable -> Option D

4. Quick Check:

   Command not found = PATH missing Deno [OK]

Hint: Check if Deno is in PATH after install to fix 'command not found' [OK]

Common Mistakes:

• Assuming a reboot is needed
• Thinking root user is required
• Believing Deno doesn't support Linux

5. You want to install Deno on macOS and ensure it is immediately available in your terminal. Which sequence of commands should you run?

hard

A. curl https://deno.land/install.sh | bash && reboot

B. brew install deno && source ~/.bash_profile

C. curl -fsSL https://deno.land/install.sh | sh && export PATH="$HOME/.deno/bin:$PATH"

D. npm install -g deno && deno --version

Solution

1. Step 1: Identify the official install method for macOS

   Running the curl script piped to sh installs Deno. Then updating PATH with export makes it available immediately.

2. Step 2: Evaluate other options

   brew install deno && source ~/.bash_profile uses Homebrew which is valid but requires shell reload; curl https://deno.land/install.sh | bash && reboot uses bash and reboot unnecessarily; npm install -g deno && deno --version uses npm which is incorrect for Deno.

3. Final Answer:

   curl -fsSL https://deno.land/install.sh | sh && export PATH="$HOME/.deno/bin:$PATH" -> Option C

4. Quick Check:

   Install + update PATH = curl -fsSL https://deno.land/install.sh | sh && export PATH="$HOME/.deno/bin:$PATH" [OK]

Hint: Install with curl script then export PATH to use Deno immediately [OK]

Common Mistakes:

• Using npm to install Deno
• Forgetting to update PATH after install
• Rebooting unnecessarily