PowerShell Trace-Command

Windows PowerShell Trace CommandPowerShell Trace-Command cmdlet

On this page I will describe how to employ PowerShell's built-in cmdlet to debug problems.  Trace-Command cmdlet initiates a record of how PowerShell attempts to execute the specified expression.

 PowerShell Trace-Command Topics

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Preparation: Choose an Expression to Trace

I like to start at the beginning with a simple PowerShell command, and then build on success.

Clear-Host
Get-ChildItem C:\

Note 1: This is just the expression that we wish to investigate with a trace.

Timeout: Investigate Components to Trace

Key Question: What specifically do we want to troubleshoot?  FileSystem, PathResolution?  Let us seek the answer by using another trace cmdlet.

Clear-Host
Get-TraceSource | Format-Table Name, Description -AutoSize

This was how I discovered PathResolution and other debug components.

Example 1: Trace-Command Filsystem

We have chosen our expression {GCI}, and we have researched the name of a component to trace (PathResolution).

Clear-Host
Trace-Command -Name PathResolution -Expression {GCI C:\} -PSHost

Note 2: Nothing gets displayed unless you append the -PSHost parameter.

Note 3: Talking of parameters, PathResolution itself is not a parameter, this is why for clarity I explicitly wrote -Name with its value of PathResolution.

Note 4: GCI is a common alias for Get-ChildItem.

Sample Output of Trace-Command

DEBUG: PathResolution Information: 0 : Path is DRIVE-QUALIFIED
DEBUG: PathResolution Information: 0 : DRIVE-RELATIVE path: \
DEBUG: PathResolution Information: 0 : Drive: C
DEBUG: PathResolution Information: 0 : Provider: Microsoft.PowerShell.Core\FileSystem
DEBUG: PathResolution Information: 0 : Resolving MSH path "C:\" to PROVIDER-INTERNAL path
DEBUG: PathResolution Information: 0 : Filter:
DEBUG: PathResolution Information: 0 : Include:
DEBUG: PathResolution Information: 0 : Exclude:
DEBUG: PathResolution Information: 0 : Path is DRIVE-QUALIFIED …..

Directory: C:\

Mode  LastWriteTime  Length  Name
—-   ————– —— —-
d-r– 28/01/2014 19:10 Program Files
d-r– 27/01/2014 10:29 Program Files (x86) ….

Note 4: There were no problems with this particular trace, to mimic an error to troubleshoot you could choose a non-exist path such as GCI V:

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Research Parameters for Trace-Command

This is how I discovered -PSHost and other useful parameters for this debugging cmdlet.

Clear-Host
Get-Help Get-TraceSource -Full

Note 5: The Help file reveals ParameterBinding

Example 2a: Trace-Command Processes

I created an array called $Names=@(, which contains interesting tracing elements.  For a working script I would just focus on the names of interest

Clear-Host
$Names=@("ParameterBinding","CommandDiscovery","TypeConversion")
Trace-Command -Name $Names {Get-Process a* -ComputerName LocalHost} -PSHost

Note 6: The expression is Get-Process.

Example 2b: Trace-Command Processes

For comprehensive debugging, I created an array $Names=@( containing all the possible tracing elements as revealed by Get-TraceSource.

Clear-Host
$Names=@("CertificateProvider", "ClientTransport", "CmdletProviderClasses", `
"CmdletProviderContext", "CommandDiscovery", "CommandHelpProvider", `
"CommandSearch", "ConsoleLineOutput", "CRPS", "CRSessionFSM", "CRSessionImpl", `
"DisplayDataQuery", "ETS", "FileSystemProvider", "FormatFileLoading", `
"FormatInfoDataClassFactory", "FormatViewBinding", "GetHelpCommand", `
"InternalDeserializer", "LocationGlobber", "MemberResolution", "Modules", `
"MshSnapinLoadUnload", "NavigationCommands", "ParameterBinderBase",`
"ParameterBinderController", "ParameterBinding", "PathResolution", `
"PowerShellISENamedPipe", "PSDriveInfo", "PSSnapInLoadUnload", `
"RegistryProvider", "RunspaceInit", "SerializedDataStream", "SessionState",`
"SessionStateProvider", "Transport", "TypeConversion", "TypeMatch")

Trace-Command -Name $Names {Get-Process a* -ComputerName LocalHost} -PSHost

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Discover Other Members of PowerShell's 'Trace' Family

Let us research other cmdlets which deal with tracing or debugging.

Clear-Host
Get-Command *trace*

Name
—-
Enable-PSTrace
Enable-PSWSManCombinedTrace
Enable-WSManTrace
Start-Trace
Stop-Trace
Get-TraceSource
Set-TraceSource
Trace-Command

See more tasks for PowerShell »

Summary of PowerShell's Trace-Command

Trace-Command cmdlet automatically configures a detailed record of the specified PowerShell expression or command.  

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Please email me if you have a better example script. Also please report any factual mistakes, grammatical errors or broken links, I will be happy to correct the fault.