Lesson -4 : Using Powershell Pipeline

19. Introduction to the Pipeline

What is a Pipeline?

👉 A pipeline passes the output of one command as input to another command

Command1 | Command2

Simple Meaning

👉
Pipeline = “Take result from one command and send it to the next command”

 

Basic Example

 >>> Get-Process | Sort-Object CPU

 What happens:

1. Get-Process → gets all processes
2. Output goes to Sort-Object
3. Processes sorted by CPU

Another Example

 >>> Get-Service | Where-Object {$_.Status -eq "Running"}

 Select Specific Data

>>> Get-Process | Select-Object Name, Id

PS C:\Windows\System32> Get-Process | Get-Member

   TypeName: System.Diagnostics.Process

Name                       MemberType     Definition
----                       ----------     ----------
Handles                    AliasProperty  Handles = Handlecount
Name                       AliasProperty  Name = ProcessName
NPM                        AliasProperty  NPM = NonpagedSystemMemorySize64
PM                         AliasProperty  PM = PagedMemorySize64
SI                         AliasProperty  SI = SessionId
VM                         AliasProperty  VM = VirtualMemorySize64
WS                         AliasProperty  WS = WorkingSet64
Parent                     CodeProperty   System.Object Parent{get=GetParentProcess;}
Disposed                   Event          System.EventHandler Disposed(System.Object, System.EventArgs)
ErrorDataReceived          Event          System.Diagnostics.DataReceivedEventHandler ErrorDataReceived(System.Object, System.Diagn…
Exited                     Event          System.EventHandler Exited(System.Object, System.EventArgs)
OutputDataReceived         Event          System.Diagnostics.DataReceivedEventHandler OutputDataReceived(System.Object, System.Diag…
BeginErrorReadLine         Method         void BeginErrorReadLine()
BeginOutputReadLine        Method         void BeginOutputReadLine()


Then you may use 

>>> Get-Process | Select-Object Name, Id, WorkingSet, SessionId

How Pipeline Works Internally

👉 PowerShell passes objects, not plain text

So each command receives structured data

Multiple Pipeline Stages

>>> Get-Process | Where-Object {$_.CPU -gt 100} | Sort-Object CPU

$_ 

👉 Represents each process (current item) being processed

$_ .CPU

👉 Accesses the CPU property of that process

-gt 100

👉 Means greater than 100

 

{$_.CPU -gt 100} =
“For each process, check if its CPU usage is greater than 100” 

Important Commands in Pipeline

Command	Purpose
Where-Object	Filter data
Select-Object	Choose properties
Sort-Object	Sort data
Measure-Object	Count/summarize

Pro Tip (Very Important)

Most used pattern:

 >>> Get-Command | Where-Object {} | Select-Object {}

 

What does Get-Command do?

It shows:

• Cmdlets
• Functions
• Scripts
• Aliases

👉 Basically, everything you can run in PowerShell

 

Cmdlets : cmdlets (pronounced command-lets) are built-in commands used to perform specific tasks.

Function: In PowerShell, a function is a custom block of code that you write once and reuse multiple times.

Alias : In PowerShell, an alias is a short name (nickname) for a command.

 

Alias	Actual Command

ls	Get-ChildItem

dir	Get-ChildItem

cd	Set-Location

cat	Get-Content

View All Aliases : Get-Alias

Find Alias for a Command : >>> Get-Alias -Definition Get-ChildItem

Find Command from Alias : >>> Get-Alias ls

Create Your Own Alias : >>> Set-Alias -Name gs -Value Get-Service

Remove Alias >>> Remove-Item Alias:gs

20. Understanding Get Member

Understanding Get-Member in PowerShell

In PowerShell,
Get-Member is used to:

👉 Inspect an object and see what it contains

What does Get-Member show?

It displays:

• Properties → Data (Name, Id, Status)
• Methods → Actions (Start(), Stop(), Kill())
• Type of object

Basic Syntax

<command> | Get-Member

>>> Get-Process | Get-Member

Output shows:

• Properties: Name, Id, CPU
• Methods: Kill(), Start()

Why is it important?

👉 Helps you:

• Understand what data is available
• Discover properties for filtering
• Learn how to manipulate objects

Example 2 (Services)

>>> Get-Service | Get-Member

Shows:

• Status
• Name
• Start() method

Using Specific Member Types

Only properties

>>> Get-Process | Get-Member -MemberType Property

Only methods

>>> Get-Process | Get-Member -MemberType Method

Practical Use

>>> Get-Process | Where-Object {$_.CPU -gt 100}

Real-Life Analogy

👉 Get-Member = “Open and inspect what’s inside an object”

Like checking:

• Features of a phone
• Functions of a machine

Related Commands

• Select properties:

>>> Get-Process | Select-Object Name, CPU

Help:

>>> Get-Help Get-Process

21 . Formatting Pipeline Output

In PowerShell, formatting pipeline output means:

👉 Controlling how results are displayed (table, list, wide, etc.)


Why Formatting is Important

• Makes output easy to read 👀
• Shows only required data 🎯
• Helps in reports 📊

Main Formatting Cmdlets

Cmdlet	Purpose
Format-Table	Display in table format
Format-List	Display as list
Format-Wide	Show only one property
Format-Custom	Advanced formatting

Format-Table (Most Used)

>>> Get-Process | Format-Table Name, CPU -AutoSize 

Format-List

>>> Get-Process | Format-List Name, Id

Format-Wide

>>> Get-Process | Format-Wide Name

👉 Shows only names in multiple columns

Format-Custom (Advanced)

>>> Get-Process | Format-Custom
👉 Shows detailed structured output

Real Example

>>> Get-Service | Where-Object {$_.Status -eq "Running"} | Format-Table Name, Status

Use -AutoSize for clean columns

Use Format-List for detailed view

Always format at the end

Format into a Text File (Most Common)

>>> Get-Process | Select Name, CPU | Format-Table -AutoSize | Out-File "C:\process.txt"

Saves formatted table into a .txt file

Format as List into File

>>> Get-Service | Format-List Name, Status | Out-File "C:\services.txt"

Export as CSV (Best for Excel)

>>> Get-Process | Select Name, CPU | Export-Csv "C:\process.csv" -NoTypeInformation

-NoTypeInformation removes the type metadata line from the CSV file.

👉 Opens in Excel cleanly

Save Raw Output (No Formatting)

>>> Get-Process | Select Name, CPU | Out-File "C:\raw.txt"

Difference Between Methods

Method	Use
Out-File	Human-readable text
Export-Csv	Structured data (Excel)
Set-Content	Simple text writing

Important Rule -- Not to do***

👉 Formatting before exporting can cause issues in CSV

❌ Wrong:

Get-Process | Format-Table | Export-Csv file.csv


22. Passing Pipeline Data ByValue

 What does Test-NetConnection do?

👉 It checks:

• If a server/website is reachable
• Port connectivity (very important)
• DNS resolution
• Network route (like traceroute)

 

Test-NetConnection <ComputerName>

Test-NetConnection google.com 

Test-NetConnection google.com -Port 80

Test-NetConnection google.com -Port 443

Test-NetConnection server -Port 3389 -Quiet

Test-NetConnection google.com -TraceRoute

 

Read a file in powershell

>>> Get-Content <file_name> 

lets say we open up a notepad , add server names line by line and  

>>> Get-Content <file_name> | Net-TestConnection  

this will ping all the servers in the file and return the result

Passing Pipeline Data ByValue in PowerShell

In PowerShell,
Passing pipeline data ByValue means:

👉 The entire object from one command is passed directly to a parameter of the next command

Simple Definition

👉 ByValue = pass the whole object automatically (no manual mapping needed)

Basic Example

 >>> Get-Service | Stop-Service

What happens:

1. Get-Service → produces service objects
2. Stop-Service → accepts those objects directly
3. Services are stopped

Why does this work?

Because:

👉 Stop-Service accepts input ByValue

  How to Check (Important)

>>> Get-Help Stop-Service -Full

👉 Look for:

Accept pipeline input?  True (ByValue)

Another Example

>>>Get-Process | Stop-Process
👉 Each process object is passed directly

How ByValue Works Internally

👉 PowerShell checks:

• Does the next cmdlet accept this object type?
• If YES → passes automatically

Pipeline Flow (ByValue)

[Process Object] → Stop-Process

 👉 Entire object goes into the command

Important Note

ByValue works only when:

✔️ Object type matches expected parameter
❌ Otherwise it won’t work

 

 ByValue vs ByPropertyName

Type	Meaning
ByValue	Whole object passed
ByPropertyName	Match property names

 Method 1 (Best - ByValue)

>>> Get-Service | Stop-Service

Method 2 (Filter + Stop)

>>> Get-Service | Where-Object {$_.Name -eq "Spooler"} | Stop-Service 

Method 3 (Explicit parameter)

>>> Get-Service | Select Name | ForEach-Object {
    Stop-Service -Name $_.Name
} 

23. Passing Pipeline Data ByPropertyName in PowerShell

In PowerShell,
ByPropertyName means:

👉 Values are passed from one command to another based on matching property names

Simple Definition

👉 ByPropertyName = match property names to parameter names

Basic Example

>>> Get-Service | Select Name | Stop-Service

What happens here?

1. Get-Service → returns service objects
2. Select Name → creates objects with property Name
3. Stop-Service → has parameter -Name

PowerShell matches:

Name (property) → -Name (parameter)

Why this works

👉 Because Stop-Service accepts pipeline input:

ByPropertyName = True

Another Example

>>> Get-Process | Select Id | Stop-Process

Matches:

Id → -Id

Check if command supports it

>>> Get-Help Stop-Service -Full

4. Using Parentheses to Change the Order of Operations (PowerShell)

In PowerShell, parentheses () are used to:

👉 Force a command or expression to run first (before the rest of the pipeline or expression)

Simple Definition

👉 () = “Do this part first”

Basic Example

>>> (Get-Process).Count

What happens?

1. Get-Process runs first
2. Returns all processes
3. .Count is applied

👉 Output: total number of processes

 

❌ Without Parentheses

Get-Process.Count

👉 ❌ Error or unexpected result
👉 Because .Count is not applied correctly

 

Real Use Case

Without parentheses

 >>> Get-Process | Select Name, CPU | Measure-Object

Works, but not flexible for further operations

With parentheses

 >>> (Get-Process | Select Name, CPU).Count

 or 

>>> (Get-Process | Select Name, CPU) | Measure-Object 

or

>>> (Get-Process) | Select Name, CPU | Measure-Object

Use in Calculations

 (5 + 3) * 2

👉 Output: 16
👉 Without parentheses → 11

 

Access Object Properties

>>> (Get-Service -Name Spooler).Status

👉 Gets status directly

Why Parentheses Matter

👉 They:

• Control execution order
• Allow property access on results
• Help in complex pipelines

Important Notes

• Always use () when accessing properties of a command
• Useful in scripting and automation
• Improves readability

Real-Life Analogy

👉 Like math:

• (2 + 3) × 5 → correct order
• Without brackets → wrong result

Simple Explanation

👉 Parentheses =
Run this first, then continue

Pro Tips

✔️ Use for counting:

>>> (Get-Process).Count

Use for filtering:

>>> (Get-Service | Where-Object {$_.Status -eq "Running"}).Count

Use for property access:

>>> (Get-Date).Day

>>> Get-Date -Format "dddd, dd MMMM yyyy HH:mm:ss"

25. Measuring Objects in PowerShell

In PowerShell, measuring objects means:

👉 Calculating count, sum, average, min, max of data

This is done using the cmdlet:

>>> Measure-Object

What does Measure-Object do?

👉 It helps you:

• Count items
• Add values
• Find average
• Find smallest / largest value

Basic Syntax

<command> | Measure-Object

Example 1: Count Objects

>>> Get-Process | Measure-Object

>>> Get-Process | Get-Member -MemberType Property

>>> Get-Process | Get-Member -MemberType Method

>>> (Get-Process | Measure-Object -Property CPU).count

>>> Get-Process | Measure-Object -Property CPU -Sum

>>> Get-Process | Measure-Object -Property CPU -Average 

 

Example 5: 
 

>> Get-Process | Measure-Object -Property CPU -Maximum -Minimum -Average -Sum

 

>>  Get-ChildItem | Measure-Object -Property Length -Sum

>>> Get-Process | Where-Object {$_.CPU -gt 100} | Measure-Object

Interview Tip

Most common:

>>> (Get-Process).Count

 

26. Sorting Objects in PowerShell

In PowerShell, sorting objects means:

👉 Arranging data in a specific order (ascending or descending)

This is done using the cmdlet:

 Sort-Object

 
What does Sort-Object do?

👉 It sorts data based on:

• Numbers
• Text
• Dates

 Basic Syntax

 <command> | Sort-Object <Property>

 Example 1: Sort Processes by CPU

>>> Get-Process | Sort-Object CPU --default is ascending

Descending Order

>>> Get-Process | Sort-Object CPU -Descending

 👉 Highest CPU first

Example 2: Sort by Name

>>> Get-Service | Sort-Object Name

Example 3: Sort Files by Size

>>> Get-ChildItem | Sort-Object Length -Descending

👉 Largest files first

Sort Multiple Properties

>>> Get-Process | Sort-Object CPU, Name

👉 First by CPU, then by Name

Select + Sort

>>> Get-Process | Select Name, CPU | Sort-Object CPU -Descending

How it Works

👉 PowerShell looks at the property value
👉 Rearranges objects accordingly

Real Example (Top 5 CPU Processes)

>>> Get-Process | Sort-Object CPU -Descending | Select-Object -First 5

>>> Get-Process | Sort-Object CPU -Descending | Select-Object -Last 6

Important Notes

• Default = Ascending order
• Works only with valid properties
• Case-insensitive sorting for text

Combine with Filtering

• Get-Process |
• Where-Object {$_.CPU -gt 100} |
• Sort-Object CPU -Descending

Interview Tip

Most common:

>>> Get-Process | Sort-Object CPU -Descending | Select -First 10

👉 Shows top 10 CPU-consuming processes

Combine Filtering + Sorting + Exporting in PowerShell

In PowerShell, you can chain multiple steps in one pipeline to:

>>> Command | Where-Object {} | Sort-Object {} | Export-Csv / Out-File 

Example 1: High CPU Processes → Sort → Export

>>>

Get-Process |
Where-Object {$_.CPU -gt 100} |
Sort-Object CPU -Descending |
Select-Object Name, CPU |
Export-Csv "C:\HighCPUProcesses.csv" -NoTypeInformation

What happens?

1. Get-Process → get all processes
2. Where-Object → filter CPU > 100
3. Sort-Object → highest CPU first
4. Select-Object → pick columns
5. Export-Csv → save to file

Example 2: Large Files Report

Get-ChildItem "C:\Logs" |
Where-Object {$_.Length -gt 10MB} |
Sort-Object Length -Descending |
Select Name, Length |
Export-Csv "C:\LargeFiles.csv" -NoTypeInformation 

EXAMPLE

>>> Get-ChildItem "C:\Users\v-sreejithba" | Where-Object {$_.length -gt "1KB"} | Sort-Object Length -Descending | Select Name, Length

Name                 Length
----                 ------
process.csv            7363
HighCPUProcesses.csv   1212

Example 3: Running Services → Export to Text

Important Rules

✅ Rule 1: Order matters

👉 Always follow:

Filter → Sort → Select → Export

❌ Rule 2: Don’t format before CSV

Wrong:

Format-Table | Export-Csv

Correct:

Select-Object | Export-Csv

 

Rule 3: Use Format-* only for text output

• Format-Table → use with Out-File
• NOT with Export-Csv

 

Example 4: Top 5 Processes Report

>>> Get-Process |
Sort-Object CPU -Descending |
Select-Object -First 5 Name, CPU |
Export-Csv "C:\TopProcesses.csv" -NoTypeInformation

Real-Life Analogy

👉 Like Excel workflow:

1. Filter rows
2. Sort data
3. Select columns
4. Save file

Simple Explanation

👉 Combine like this:

Get-Data | Filter | Sort | Select | Export

 

Pro Tips

✔️ Use -Descending for top results
✔️ Use -First for top N records
✔️ Always clean output with Select-Object

 

 

27. Selecting Objects in PowerShell

In PowerShell, selecting objects means:

👉 Choosing specific properties or items from the output

This is done using:

 Select-Object

 What does Select-Object do?

👉 It helps you:

• Pick specific properties (columns)
• Limit number of results
• Create custom output

 Basic Syntax

 <command> | Select-Object <Property1>, <Property2>

Example 1: Select Properties 

>>> Get-Process | Select-Object Name, CPU

👉 Output shows only:

• Name
• CPU

Example 2: First Few Objects

>>> Get-Process | Select-Object -First 5

👉 Shows first 5 processes

Example 3: Last Few Objects

>>> Get-Process | Select-Object -Last 5

Example 4: Unique Values

>>> Get-Service | Select-Object Name -Unique

 Lists all services but shows only unique service names (no duplicates)

Example 5: Expand Property

>>> Get-Process | Select-Object -ExpandProperty Name

 👉 Outputs only the process names as plain text (not objects) . Returns only values (not objects)

Example 6: Calculated Property

>>> Get-Process | Select-Object Name, @{Name="CPU_Usage"; Expression={$_.CPU}}

Displays process name and CPU usage, but renames the CPU column to CPU_Usage

Combine with Sorting

>>> Get-Process |  Sort-Object CPU -Descending | Select-Object -First 5 Name, CPU

👉 Top 5 CPU processes

Important Notes

• Select-Object changes the object structure
• Use carefully before actions like Stop-Process
• Best used for:
  • Display
  • Export

Real-Life Analogy

👉 Like choosing columns in Excel:

• Hide unwanted columns
• Show only needed data

Interview Tip

Most used:

>>> Get-Process | Select Name, Id, CPU

28. Creating Calculated Properties Using Select-Object

In PowerShell,
calculated properties let you:

👉 Create new columns (custom fields) based on existing data

🔑 Simple Definition

👉 Calculated Property =
A new property created using an expression

Basic Syntax

Select-Object Property1, @{Name="NewColumn"; Expression={ <logic> }}

Example 1: Rename Property

>>> Get-Process | Select-Object Name, @{Name="CPU_Usage"; Expression={$_.CPU}}

Output:

Name      CPU_Usage
----      ----------
chrome    120
notepad   5 

Example 2: Convert Units (Bytes → MB)

>>> Get-ChildItem | Select-Object Name,
@{Name="SizeMB"; Expression={ $_.Length / 1MB }}

Example 3: Round Values

>>> Get-ChildItem | Select-Object Name,
@{Name="SizeMB"; Expression={ [math]::Round($_.Length / 1MB, 2) }}

Example 4: Custom Date Format

>>> Get-Process | Select Name,
@{Name="StartDate"; Expression={ $_.StartTime.ToString("yyyy-MM-dd") }}

Example 5: Conditional Logic

>>> Get-Process | Select Name,
@{Name="HighCPU"; Expression={ if ($_.CPU -gt 100) {"Yes"} else {"No"} }}

Example 6: Multiple Calculated Properties

>>> Get-Process | Select Name,
@{Name="CPU"; Expression={$_.CPU}},
@{Name="MemoryMB"; Expression={ $_.WorkingSet / 1MB }}

How it Works

Part	Meaning
@{}	Hashtable
Name	New column name
Expression	Logic to calculate value

Combine with Export

Get-Process |
Select Name,
@{Name="CPU"; Expression={$_.CPU}},
@{Name="MemoryMB"; Expression={ $_.WorkingSet / 1MB }} |
Export-Csv "C:\ProcessReport.csv" -NoTypeInformation

29. Filtering Objects in PowerShell

In PowerShell,
filtering objects means:

👉 Selecting only the data that meets specific conditions

Main Cmdlet

>>  Where-Object


Basic Syntax

<command> | Where-Object { condition }

Key Concept

👉 Inside {}:

• $_ = current object
• You apply a condition

Example 1: Filter Running Services

>>> Get-Service | Where-Object {$_.Status -eq "Running"}

👉 Shows only running services

Example 2: Filter High CPU Processes

>>> Get-Process | Where-Object {$_.CPU -gt 100}

👉 Shows processes using more CPU

Example 3: Filter Files by Size

>>> Get-ChildItem | Where-Object {$_.Length -gt 10MB}

👉 Files larger than 10 MB

Comparison Operators

Operator	Meaning
-eq	Equal
-ne	Not equal
-gt	Greater than
-lt	Less than
-ge	Greater or equal
-le	Less or equal
-like	Pattern match
-match	Regex match

Example 4: Filter by Name

>>> Get-Process | Where-Object {$_.Name -like "*chrome*"}

Example 5: Case-insensitive match 

>>> Get-Service | Where-Object {$_.Name -match "win"}

Multiple Conditions

>>> Get-Process |
Where-Object { $_.CPU -gt 100 -and $_.Name -like "*chrome*" }

Combine with Sorting

>>> Get-Process |
Where-Object {$_.CPU -gt 50} |
Sort-Object CPU -Descending

Important Notes

• Filtering happens after data is retrieved
• Works on object properties
• Can impact performance for large data