Automatic variables ($_, $PSVersionTable) in PowerShell - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to display the PowerShell version using the automatic variable.

PowerShell

Write-Output $[1].PSVersion

Drag options to blanks, or click blank then click option'

A$_

B$PSVersionTable

C$Version

D$PSVersion

Attempts:

3 left

💡 Hint

Common Mistakes

Using $_ instead of $PSVersionTable

Trying to use $Version which is not automatic

Using $PSVersion which is not defined

The automatic variable $PSVersionTable holds details about the PowerShell version. Accessing PSVersion property shows the version.

2fill in blank

medium

Complete the code to output each item in the pipeline using the automatic variable.

PowerShell

Get-Process | ForEach-Object { Write-Output [1] }

Drag options to blanks, or click blank then click option'

A$_

B$PSVersionTable

C$this

D$item

Attempts:

3 left

💡 Hint

Common Mistakes

Using $PSVersionTable inside pipeline which is unrelated

Using $this or $item which are not automatic variables in PowerShell

The automatic variable $_ represents the current object in the pipeline inside script blocks.

3fill in blank

hard

Fix the error in the code to correctly display the PowerShell version major number.

PowerShell

Write-Output $PSVersionTable.[1].Major

Drag options to blanks, or click blank then click option'

AVersion

BVersionTable

CPSVersion

DPSVersionTable

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Version' instead of 'PSVersion' property

Trying to access 'VersionTable' or 'PSVersionTable' as properties

The property holding the version object inside $PSVersionTable is PSVersion. Accessing Major gives the major version number.

4fill in blank

hard

Fill both blanks to filter processes with CPU time greater than 100 and output their names.

PowerShell

Get-Process | Where-Object { $_.[1] -gt 100 } | ForEach-Object { Write-Output $_.[2] }

Drag options to blanks, or click blank then click option'

ACPU

BName

CId

DHandles

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Id' or 'Handles' instead of 'CPU' for filtering

Outputting 'Id' instead of 'Name' for process names

The CPU property holds the CPU time used by a process. Filtering with -gt 100 selects processes using more than 100 CPU seconds. Then outputting the Name property shows their names.

5fill in blank

hard

Fill all three blanks to create a hashtable of process names and their IDs for processes with IDs less than 1000.

PowerShell

Get-Process | Where-Object { $_.[1] [2] 1000 } | ForEach-Object { $result[$_.[3]] = $_.Id }

Drag options to blanks, or click blank then click option'

AId

B<

CProcessName

DName

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ProcessName' instead of 'Name' for the key

Using '>' instead of '<' for filtering

Using wrong property for filtering instead of 'Id'

The Id property is used to filter processes with IDs less than 1000 using <. The Name property is used as the key in the hashtable to store process IDs.

Practice

1. What does the automatic variable $_ represent in a PowerShell pipeline?

easy

A. The version of PowerShell installed

B. The current object being processed in the pipeline

C. The last error message generated

D. The total number of commands run

Solution

1. Step 1: Understand the role of $_ in pipelines

   $_ is a special variable that holds the current item being processed in a pipeline command.

2. Step 2: Differentiate from other automatic variables

   $PSVersionTable shows version info, errors use $Error, and command counts are not stored in $_.

3. Final Answer:

   The current object being processed in the pipeline -> Option B

4. Quick Check:

   $_ = current pipeline item [OK]

Hint: Remember: $_ always means current pipeline item [OK]

Common Mistakes:

• Confusing $_ with $PSVersionTable
• Thinking $_ holds error info
• Assuming $_ is a global variable

2. Which of the following is the correct way to display the PowerShell version using $PSVersionTable?

easy

A. Write-Output $PSVersionTable.VersionInfo

B. Write-Output $_.Version

C. Write-Output $PSVersion.VersionTable

D. Write-Output $PSVersionTable.Version

Solution

1. Step 1: Identify the correct property of $PSVersionTable

   The property Version holds the PowerShell version number.

2. Step 2: Confirm the syntax to output the version

   Write-Output $PSVersionTable.Version correctly prints the version; other options use wrong variable names or properties.

3. Final Answer:

   Write-Output $PSVersionTable.Version -> Option D

4. Quick Check:

   $PSVersionTable.Version outputs version [OK]

Hint: Use $PSVersionTable.Version to get PowerShell version [OK]

Common Mistakes:

• Using $_ instead of $PSVersionTable
• Swapping property names incorrectly
• Assuming $PSVersionTable is a method

3. What will be the output of this PowerShell command?

1..3 | ForEach-Object { "Number: $_" }

medium

A. Number: 1 Number: 2 Number: 3

B. Number: $_ Number: $_ Number: $_

C. 1 2 3

D. Error: $_ is undefined

Solution

1. Step 1: Understand the pipeline and $_ usage

   The pipeline sends numbers 1 to 3 one by one to ForEach-Object. Inside the script block, $_ holds the current number.

2. Step 2: Evaluate the output string for each number

   Each iteration outputs "Number: 1", then "Number: 2", then "Number: 3" on separate lines.

3. Final Answer:

   Number: 1 Number: 2 Number: 3 -> Option A

4. Quick Check:

   Pipeline item $_ prints each number [OK]

Hint: $_ holds current pipeline item inside ForEach-Object [OK]

Common Mistakes:

• Thinking $_ is a literal string
• Expecting all output on one line without spaces
• Confusing $_ with a variable outside pipeline

4. Identify the error in this script snippet:

Get-Process | Where-Object { $_.Name -eq 'powershell' } | ForEach-Object { Write-Output $PSVersionTable }

medium

A. The script outputs the entire $PSVersionTable multiple times unnecessarily

B. Using $PSVersionTable inside ForEach-Object is invalid

C. $_ is not defined inside Where-Object script block

D. Get-Process cannot be piped to Where-Object

Solution

1. Step 1: Analyze the pipeline and variable usage

   The pipeline filters processes named 'powershell' and then outputs $PSVersionTable for each matching process.

2. Step 2: Identify inefficiency or error

   $PSVersionTable is a static variable; outputting it inside the loop repeats the same info multiple times unnecessarily.

3. Final Answer:

   The script outputs the entire $PSVersionTable multiple times unnecessarily -> Option A

4. Quick Check:

   Repeated $PSVersionTable output inside loop [OK]

Hint: Avoid repeating static variables inside loops [OK]

Common Mistakes:

• Thinking $PSVersionTable is undefined in pipeline
• Believing $_ is invalid in Where-Object
• Assuming Get-Process can't be piped

5. You want to list all running processes and display their names along with your PowerShell version once at the end. Which script correctly uses $_ and $PSVersionTable to achieve this?

hard

A. Get-Process | ForEach-Object { Write-Output "Process: $PSVersionTable.Version" }; Write-Output "PowerShell Version: $_.Name"

B. Get-Process | ForEach-Object { Write-Output "Process: $_.Name; PowerShell Version: $PSVersionTable.Version" }

C. Get-Process | ForEach-Object { Write-Output "Process: $_.Name" }; Write-Output "PowerShell Version: $PSVersionTable.Version"

D. Write-Output "PowerShell Version: $PSVersionTable.Version"; Get-Process | ForEach-Object { Write-Output "Process: $_.Name" }

Solution

1. Step 1: Understand the requirement to show processes and version separately

   We want to list each process name using $_ inside the pipeline, then show PowerShell version once after.

2. Step 2: Evaluate each option's correctness

   Get-Process | ForEach-Object { Write-Output "Process: $_.Name" }; Write-Output "PowerShell Version: $PSVersionTable.Version" lists processes with $_ correctly, then outputs version once after the loop. Get-Process | ForEach-Object { Write-Output "Process: $_.Name; PowerShell Version: $PSVersionTable.Version" } repeats version for each process. Write-Output "PowerShell Version: $PSVersionTable.Version"; Get-Process | ForEach-Object { Write-Output "Process: $_.Name" } outputs version first, then processes (order reversed). Get-Process | ForEach-Object { Write-Output "Process: $PSVersionTable.Version" }; Write-Output "PowerShell Version: $_.Name" misuses variables inside the loop.

3. Final Answer:

   Get-Process | ForEach-Object { Write-Output "Process: $_.Name" }; Write-Output "PowerShell Version: $PSVersionTable.Version" -> Option C

4. Quick Check:

   List processes with $_, version once after [OK]

Hint: Output static info after pipeline, use $_ inside pipeline [OK]

Common Mistakes:

• Repeating version output inside loop
• Mixing order of outputs
• Using wrong variable names inside pipeline