Automatic variables ($_, $PSVersionTable) in PowerShell - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this PowerShell pipeline?

Consider the following PowerShell command:

1..3 | ForEach-Object { $_ * 2 }

What is the output?

PowerShell

1..3 | ForEach-Object { $_ * 2 }

A 1 2 3

B Error: $_ is undefined

C 0 2 4

D 2 4 6

💡 Hint

$_ represents the current item in the pipeline inside ForEach-Object.

In PowerShell, $_ is the automatic variable for the current pipeline object. Multiplying each number 1, 2, 3 by 2 results in 2, 4, 6.

💻 Command Output

intermediate

What does $PSVersionTable.PSVersion.Major return?

If you run this command in PowerShell:

$PSVersionTable.PSVersion.Major

What kind of value will it return?

PowerShell

$PSVersionTable.PSVersion.Major

A A boolean indicating if PowerShell is installed

B A string with the full PowerShell version

C An integer representing the major version number of PowerShell

D An error because $PSVersionTable is undefined

💡 Hint

$PSVersionTable contains version info as properties.

$PSVersionTable is an automatic variable holding version info. PSVersion is a version object, and Major is its major version number as an integer.

📝 Syntax

advanced

Which option correctly uses $_ in a Where-Object filter?

You want to filter numbers greater than 5 from a list using Where-Object. Which of these commands is correct?

A 1..10 | Where-Object { $_ -gt 5 }

B 1..10 | Where-Object { $ -gt 5 }

C 1..10 | Where-Object { $_ > 5 }

D 1..10 | Where-Object { $_ -lt 5 }

💡 Hint

Use the correct comparison operator and variable name.

Option A uses $_ (current object) and the correct PowerShell comparison operator '-gt' for 'greater than'. Option A uses '>' which is invalid in PowerShell filters.

🔧 Debug

advanced

Why does this script fail to filter correctly?

Given this script:

1..5 | ForEach-Object { if ($_ % 2) { $_ } }

It outputs 1 3 5 but you want only even numbers. What is wrong?

PowerShell

1..5 | ForEach-Object { if ($_ % 2) { $_ } }

A The condition '$_ % 2' is true for odd numbers, so it outputs odds instead of evens

B $_ is not defined inside ForEach-Object, causing an error

C The script is missing a closing brace '}'

D The pipeline operator '|' is used incorrectly

💡 Hint

Remember how modulo (%) works with odd and even numbers.

The expression '$_ % 2' returns 1 for odd numbers (true) and 0 for even (false). So the if condition passes for odd numbers, outputting them. To get evens, check for '$_ % 2 -eq 0'.

🚀 Application

expert

How to display PowerShell version in a formatted string?

You want to print the PowerShell version as:

PowerShell version: X.Y.Z

using $PSVersionTable. Which command produces this exact output?

A Write-Output "PowerShell version: $PSVersionTable.PSVersion.Major.$PSVersionTable.PSVersion.Minor.$PSVersionTable.PSVersion.Build"

B Write-Output "PowerShell version: $($PSVersionTable.PSVersion.Major).$($PSVersionTable.PSVersion.Minor).$($PSVersionTable.PSVersion.Build)"

C Write-Output "PowerShell version: $_.PSVersion.Major.$_.PSVersion.Minor.$_.PSVersion.Build"

D Write-Output "PowerShell version: $PSVersionTable[PSVersion][Major].[Minor].[Build]"

💡 Hint

Use subexpressions $() to embed properties inside strings.

Option B correctly uses subexpressions $() to insert each version part inside the string. Option B treats properties as literal text. Option B uses $_ which is undefined here. Option B uses invalid syntax for property access.