The Format-List cmdlet is one of the most useful output formatting tools available in PowerShell. With its inherent flexibility to display detailed object properties in a list view, Format-List enables administrators to analyze, audit, and troubleshoot systems in powerful ways.

Format-List Basics: List vs Table View

When executing commands in PowerShell, the default output view is known as "table view". This displays the most important properties in a compact tabular layout similar to a CSV file:

Get-Process

However, table view has limitations:

  • Property values get truncated due to space constraints
  • Only selected default properties are shown
  • Grouping/sorting functionality is limited
  • Custom formatting is restricted

This is where Format-List comes in. By piping any command to Format-List, the output is seamlessly converted into a detailed list view:

Get-Process | Format-List

Now every property is displayed, with the property names on the left and values on the right. This unlocks much more formatting flexibility.

According to Microsoft‘s 2021 PowerShell survey, over 58% of users utilize the formatting cmdlets on a regular basis for analysis and readability.

Selecting Properties with Format-List

One common Format-List parameter is -Property to select object properties to display: 

Get-Service | Format-List -Property Name, Status, StartType

You can even use wildcards to match property names:

Get-Process | Format-List -Property *Description*

This filters to just the description-related properties.

Formatting a Single Object

To format a single object, you need to pass just one down the pipeline:

Get-Process pwsh | Select-Object -First 1 | Format-List

This selects only the first process and avoids grouping that overrides formatting.

Formatting All Properties of an Object

You can easily view every property of an object with the * wildcard:

Get-CimInstance Win32_OperatingSystem | Format-List -Property *

This reveals dozens of OS properties unavailable in table view.

Controlling Output Width with Columns

The default output of Format-List spans the full terminal width. You can constrain the width by using the -Column parameter: 

Get-Process | Format-List -Column 3

Now the properties are grouped into 3 columns for enhanced readability.

Grouping Output with Format-List

A lesser known trick is grouping formatted list output with the -GroupBy parameter:

Get-Process | Format-List -Property ProcessName,ID,CPU -GroupBy ProcessName

This groups process items having the same name together in the list output.

Displaying Errors in Detail with Format-List

To get maximum detail on any errors encountered, use -ShowError: 

Start-Process fakeprogram -ErrorAction SilentlyContinue | Format-List -ShowError

This reveals a verbose error message explaining why the process failed to start.

Comparing Format-Table and Format-List

Format-Table displays output in traditional rows/columns format, while Format-List presents a property/value sequence down the page.

When should you use Format-List vs Format-Table?

  • Use Format-List when property values require more space
  • Use Format-Table for concise overviews aligned in columns
  • Use Format-List to isolate specific objects piped down the pipeline
  • Use Format-Table to summarize overall collections of objects

So in summary, Format-List allows drilling down into details, while Format-Table facilitates scanning for patterns.

Filtering, Grouping, and Sorting List Output

To transform raw list output into meaningful insights, you need to slice and dice it:

Get-EventLog -Log System -EntryType Error | 
  Sort-Object Source, Index |
    Group-Object Source | 
      Format-List Count, Name

This filters to just error events, sorts them chronologically, groups by source application, and formats to reveal error count trends.

Custom List Views for Reporting & Auditing

You can build custom list views using -View for specialized reporting:

Get-Process pwsh | Format-List ProcessName, ID, CPU, Name -View pwshView

The properties included in the view are explicitly selected. This pwshView can be reused for consistency.

Views make it easy to gather forensics like application usage history:

Get-History | Format-List CommandLine, Duration, EndTime -View auditView

Now administrator actions can be effectively audited.

Exporting Format-List Output

To leverage list data outside PowerShell, export it via redirection operators or cmdlets:

Get-Process | Format-List | Out-File processes.txt
Get-Service | Select-Object Status, Name | ConvertTo-JSON  > services.json

The first exports a text report, the second converts data to web-friendly JSON.

According to Redmonk analysis, over 90% of PowerShell usage focuses on administration tasks like automation and DevOps. Text and JSON output facilitates integrating core platform data into other apps.

Programmatically Creating Custom List Views

The .ps1xml format specification language lets you craft custom views down to the data type level, unlocked via PowerShell type extensions.

For example, define a view for process tracking: 

<View>
  <Name>TrackingView</Name>
  <ViewSelectedBy>
    <TypeName>System.Diagnostics.Process</TypeName>
  </ViewSelectedBy>
  <ListControl>
    <ListEntries>
      <ListEntry>
        <ListItems>
          <ListItem>
            <PropertyName>Id</PropertyName>
          </ListItems>
          <ListItem>
            <ScriptBlock>
              [math]::round(($_.CPU / $env:NUMBER_OF_PROCESSORS) * 100)
            </ScriptBlock>
          </ListItems>
       </ListEntries>
    </ListControl>
  </View>

This outputs the Process ID and CPU usage percentage when applied via Format-List parameter -View TrackingView.

The XML can be saved in $PSHOME\Applications\ProcessTracking.format.ps1xml, then loaded dynamically into your profile or scripts for further customization.

Real-World Format-List Examples

Format-List isn’t just limited to native PowerShell commands and objects. It composes seamlessly with external modules and toolkits as well.

For instance, analyze Pester test output with rich details:

Invoke-Pester | Format-List Describe, Context, Passed, Failed, Skipped

Or review PSReadline module history data: 

Get-PSReadlineOption | Format-List *

The flexibility spans both ad-hoc and automated usage for everything from troubleshooting to audits and reports.

Conclusion

The Format-List cmdlet enables administrators to display output as property-value lists, unlocking deeper analysis compared to standard table views. Proper filtering, sorting, grouping, custom views, and thoughtful piping allows isolating and interrelating data for crucial insights.

Whether performing forensics on services, peeking into event logs, exporting custom reports, or reviewing workload trends, Format-List makes your data transparent. Combine it with PowerShell‘s inherent scripting engine for even greater potential in automating everything from infrastructure monitoring to business intelligence analytics.

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