Chapter 2 - The Help System
Two groups of IT pros were given a written test without access to a computer to determine their skill level with PowerShell. PowerShell beginners were placed in one group and experts in another. Based on the results of the test, there didn't seem to be much difference in the skill level between the two groups. Both groups were given a second test similar to the first one. This time they were given access to a computer with PowerShell that didn't have access to the internet. The results of the second test showed a huge difference in the skill level between the two groups. Experts don't always know the answers, but they know how to figure out the answers.
What was the difference in the results of the first and second test between these two groups?
The differences observed in these two tests were because experts don't memorize how to use thousands of commands in PowerShell. They learn how to use the help system within PowerShell extremely well. This allows them to find the necessary commands when needed and how to use those commands once they've found them.
I've heard Jeffrey Snover, the inventor of PowerShell, tell a similar story a number of times.
Mastering the help system is the key to being successful with PowerShell.
Discoverability
Compiled commands in PowerShell are called cmdlets. Cmdlet is pronounced "command-let" (not
CMD-let). Cmdlets names have the form of singular "Verb-Noun" commands to make them easily
discoverable. For example, the cmdlet for determining what processes are running is Get-Process
and the cmdlet for retrieving a list of services and their statuses is Get-Service. There are
other types of commands in PowerShell such as aliases and functions that will be covered later in
this book. The term PowerShell command is a generic term that's often used to refer to any type of
command in PowerShell, regardless of whether or not it's a cmdlet, function, or alias.
The Three Core Cmdlets in PowerShell
Get-CommandGet-HelpGet-Member(covered in chapter 3)
One question I'm often asked is how do you figure out what the commands are in PowerShell? Both
Get-Command and Get-Help can be used to determine the commands.
Get-Help
Get-Help is a multipurpose command. Get-Help helps you learn how to use commands once you find
them. Get-Help can also be used to help locate commands, but in a different and more indirect way
when compared to Get-Command.
When Get-Help is used to locate commands, it first searches for wildcard matches of command names
based on the provided input. If it doesn't find a match, it searches through the help topics
themselves, and if no match is found an error is returned. Contrary to popular belief, Get-Help
can be used to find commands that don't have help topics.
The first thing you need to know about the help system in PowerShell is how to use the Get-Help
cmdlet. The following command is used to display the help topic for Get-Help.
Get-Help -Name Get-Help
Do you want to run Update-Help?
The Update-Help cmdlet downloads the most current Help files for Windows PowerShell
modules, and installs them on your computer. For more information about the Update-Help
cmdlet, see http://go.microsoft.com/fwlink/?LinkId=210614.
[Y] Yes [N] No [S] Suspend [?] Help (default is "Y"):
Beginning with PowerShell version 3, PowerShell help doesn't ship with the operating system. The
first time Get-Help is run for a command, the previous message is displayed. If the help
function or man alias is used instead of the Get-Help cmdlet, you don't receive this prompt.
Answering yes by pressing Y runs the Update-Help cmdlet, which requires internet access
by default. Y can be specified in either upper or lower case.
Once the help is downloaded and the update is complete, the help topic is returned for the specified command:
Get-Help -Name Get-Help
Take a moment to run that example on your computer, review the output, and take note of how the information is grouped:
- NAME
- SYNOPSIS
- SYNTAX
- DESCRIPTION
- RELATED LINKS
- REMARKS
As you can see, help topics can contain an enormous amount of information and this isn't even the entire help topic.
While not specific to PowerShell, a parameter is a way to provide input to a command. Get-Help has
many parameters that can be specified in order to return the entire help topic or a subset of
it.
The syntax section of the help topic shown in the previous set of results lists all of the
parameters for Get-Help. At first glance, it appears the same parameters are listed six different
times. Each of those different blocks in the syntax section is a parameter set. This means the
Get-Help cmdlet has six different parameter sets. If you take a closer look, you'll notice that at
least one parameter is different in each of the parameter sets.
Parameter sets are mutually exclusive. Once a unique parameter that only exists in one of the parameter sets is used, only parameters contained within that parameter set can be used. For example, both the Full and Detailed parameters couldn't be specified at the same time because they are in different parameter sets.
Each of the following parameters are in different parameter sets:
- Full
- Detailed
- Examples
- Online
- Parameter
- ShowWindow
All of the cryptic syntax such as square and angle brackets in the syntax section means something but will be covered in Appendix A of this book. While important, learning the cryptic syntax is often difficult to retain for someone who is new to PowerShell and may not use it everyday.
For more information to better understand the cryptic syntax, see Appendix A.
For beginners, there's an easier way to figure out the same information except in plain language.
When the Full parameter of Get-Help is specified, the entire help topic is returned.
Get-Help -Name Get-Help -Full
Take a moment to run that example on your computer, review the output, and take note of how the information is grouped:
- NAME
- SYNOPSIS
- SYNTAX
- DESCRIPTION
- PARAMETERS
- INPUTS
- OUTPUTS
- NOTES
- EXAMPLES
- RELATED LINKS
Notice that using the Full parameter returned several additional sections, one of which is the PARAMETERS section that provides more information than the cryptic SYNTAX section.
The Full parameter is a switch parameter. A parameter that doesn't require a value is called a switch parameter. When a switch parameter is specified, its value is true and when it's not, its value is false.
If you've been working through this chapter in the PowerShell console, you noticed that the previous
command to display the full help topic for Get-Help flew by on the screen without giving you a
chance to read it. There's a better way.
Help is a function that pipes Get-Help to a function named more, which is a wrapper for the
more.com executable file in Windows. In the PowerShell console, help provides one page of help
at a time. In the ISE, it works the same way as Get-Help. My recommendation is to use the help
function instead of the Get-Help cmdlet since it provides a better experience and it's less to
type.
Less typing isn't always a good thing, however. If you're going to save your commands as a script or share them with someone else, be sure to use full cmdlet and parameter names. The full names are self-documenting, which makes them easier to understand. Think about the next person that has to read and understand your commands. It could be you. Your coworkers and future self will thank you.
Try running the following commands in the PowerShell console on your Windows 10 lab environment computer.
Get-Help -Name Get-Help -Full
help -Name Get-Help -Full
help Get-Help -Full
Did you notice any differences in the output from the previously listed commands when you ran them on your Windows 10 lab environment computer?
There aren't any differences other than the last two options return the results one page at a time.
The spacebar is used to display the next page of content when using the Help function
and Ctrl+C cancels commands that are running in the PowerShell console.
The first example uses the Get-Help cmdlet, the second uses the Help function, and the third
omits the Name parameter when using the Help function. Name is a positional parameter and
it's being used positionally in that example. This means the value can be specified without
specifying the parameter name, as long as the value itself is specified in the correct position. How
did I know what position to specify the value in? By reading the help as shown in the following
example.
help Get-Help -Parameter Name
-Name <String>
Gets help about the specified command or concept. Enter the name of a cmdlet, function,
provider, script, or workflow, such as Get-Member, a conceptual article name, such as
about_Objects, or an alias, such as ls. Wildcard characters are permitted in cmdlet and
provider names, but you can't use wildcard characters to find the names of function help and
script help articles.
To get help for a script that isn't located in a path that's listed in the $env:Path
environment variable, type the script's path and file name.
If you enter the exact name of a help article, Get-Help displays the article contents.
If you enter a word or word pattern that appears in several help article titles, Get-Help
displays a list of the matching titles.
If you enter a word that doesn't match any help article titles, Get-Help displays a list of
articles that include that word in their contents.
The names of conceptual articles, such as about_Objects, must be entered in English, even in
non-English versions of PowerShell.
Required? false
Position? 0
Default value None
Accept pipeline input? True (ByPropertyName)
Accept wildcard characters? true
Notice that in the previous example, the Parameter parameter was used with the Help function to only return information from the help topic for the Name parameter. This is much more concise than trying to manually sift through what sometimes seems like a hundred page help topic.
Based on those results, you can see that the Name parameter is positional and must be specified in position zero (the first position) when used positionally. The order that parameters are specified in doesn't matter if the parameter name is specified.
One other important piece of information is that the Name parameter expects the datatype for its
value to be a single string, which is denoted by <String>. If it accepted multiple strings, the
datatype would be listed as <String[]>.
Sometimes you simply don't want to display the entire help topic for a command. There are a number
of other parameters besides Full that can be specified with Get-Help or Help. Try running
the following commands on your Windows 10 lab environment computer:
Get-Help -Name Get-Command -Full
Get-Help -Name Get-Command -Detailed
Get-Help -Name Get-Command -Examples
Get-Help -Name Get-Command -Online
Get-Help -Name Get-Command -Parameter Noun
Get-Help -Name Get-Command -ShowWindow
I typically use help <command name> with the Full or Online parameter. If I'm only
interested in the examples, I'll use the Examples parameter and if I'm only interested in a
specific parameter, I'll use the Parameter parameter. The ShowWindow parameter opens the
help topic in a separate searchable window that can be placed on a different monitor if you have
multiple monitors. I've avoided the ShowWindow parameter because there's a known bug where it
doesn't display the entire help topic.
If you want help in a separate window, my recommendation is to either use the Online parameter
or use the Full parameter and pipe the results to Out-GridView, as shown in the following
example.
help Get-Command -Full | Out-GridView
Both the Out-GridView cmdlet and the ShowWindow parameter of the Get-Help cmdlet require an
operating system with a GUI (Graphical User Interface). They will generate an error message if you
attempt to use either of them on Windows Server that's been installed using the server core (no-GUI)
installation option.
To use Get-Help to find commands, use the asterisk (*) wildcard character with the Name
parameter. Specify a term that you're searching for commands on as the value for the Name
parameter as shown in the following example.
help *process*
Name Category Module Synopsis
---- -------- ------ --------
Enter-PSHostProcess Cmdlet Microsoft.PowerShell.Core Connects to and ...
Exit-PSHostProcess Cmdlet Microsoft.PowerShell.Core Closes an intera...
Get-PSHostProcessInfo Cmdlet Microsoft.PowerShell.Core
Debug-Process Cmdlet Microsoft.PowerShell.M... Debugs one or mo...
Get-Process Cmdlet Microsoft.PowerShell.M... Gets the process...
Start-Process Cmdlet Microsoft.PowerShell.M... Starts one or mo...
Stop-Process Cmdlet Microsoft.PowerShell.M... Stops one or mor...
Wait-Process Cmdlet Microsoft.PowerShell.M... Waits for the pr...
Get-AppvVirtualProcess Function AppvClient ...
Start-AppvVirtualProcess Function AppvClient ...
In the previous example, the * wildcard characters are not required and omitting them produces the
same result. Get-Help automatically adds the wildcard characters behind the scenes.
help process
The previous command produces the same results as specifying the * wildcard character on each end
of process.
I prefer to add them since that's the option that always works consistently. Otherwise, they are required in certain scenarios and not others. As soon as you add a wildcard character in the middle of the value, they're no longer automatically added behind the scenes to the value you specified.
help pr*cess
No results are returned by that command unless the * wildcard character is added to the beginning,
end, or both the beginning and end of pr*cess.
If the value you specified begins with a dash, then an error is generated because PowerShell
interprets it as a parameter name and no such parameter name exists for the Get-Help cmdlet.
help -process
If what you're attempting to look for are commands that end with -process, you only need to add
the * wildcard character to the beginning of the value.
help *-process
When searching for PowerShell commands with Get-Help, you want to be a little more vague instead
of being too specific with what you're searching for.
Searching for process earlier found only commands that contained process in the name of the
command and returned only those results. When Get-Help is used to search for processes, it
doesn't find any matches for command names, so it performs a search of every help topic in
PowerShell on your system and returns any matches it finds. This causes it to return an enormous
number of results.
Get-Help processes
Name Category Module Synopsis
---- -------- ------ --------
Disconnect-PSSession Cmdlet Microsoft.PowerShell.Core Disconnects from...
Enter-PSHostProcess Cmdlet Microsoft.PowerShell.Core Connects to and ...
ForEach-Object Cmdlet Microsoft.PowerShell.Core Performs an oper...
Get-PSSessionConfiguration Cmdlet Microsoft.PowerShell.Core Gets the registe...
New-PSTransportOption Cmdlet Microsoft.PowerShell.Core Creates an objec...
Out-Host Cmdlet Microsoft.PowerShell.Core Sends output to ...
Where-Object Cmdlet Microsoft.PowerShell.Core Selects objects ...
Clear-Variable Cmdlet Microsoft.PowerShell.U... Deletes the valu...
Compare-Object Cmdlet Microsoft.PowerShell.U... Compares two set...
Convert-String Cmdlet Microsoft.PowerShell.U... Formats a string...
ConvertFrom-Csv Cmdlet Microsoft.PowerShell.U... Converts object ...
ConvertTo-Html Cmdlet Microsoft.PowerShell.U... Converts Microso...
ConvertTo-Xml Cmdlet Microsoft.PowerShell.U... Creates an XML-b...
Debug-Runspace Cmdlet Microsoft.PowerShell.U... Starts an intera...
Export-Csv Cmdlet Microsoft.PowerShell.U... Converts objects...
Export-FormatData Cmdlet Microsoft.PowerShell.U... Saves formatting...
Format-List Cmdlet Microsoft.PowerShell.U... Formats the outp...
Format-Table Cmdlet Microsoft.PowerShell.U... Formats the outp...
Get-Random Cmdlet Microsoft.PowerShell.U... Gets a random nu...
Get-Unique Cmdlet Microsoft.PowerShell.U... Returns unique i...
Group-Object Cmdlet Microsoft.PowerShell.U... Groups objects t...
Import-Clixml Cmdlet Microsoft.PowerShell.U... Imports a CLIXML...
Import-Csv Cmdlet Microsoft.PowerShell.U... Creates table-li...
Measure-Object Cmdlet Microsoft.PowerShell.U... Calculates the n...
Out-File Cmdlet Microsoft.PowerShell.U... Sends output to ...
Out-GridView Cmdlet Microsoft.PowerShell.U... Sends output to ...
Select-Object Cmdlet Microsoft.PowerShell.U... Selects objects ...
Set-Variable Cmdlet Microsoft.PowerShell.U... Sets the value o...
Sort-Object Cmdlet Microsoft.PowerShell.U... Sorts objects by...
Tee-Object Cmdlet Microsoft.PowerShell.U... Saves command ou...
Trace-Command Cmdlet Microsoft.PowerShell.U... Configures and s...
Write-Output Cmdlet Microsoft.PowerShell.U... Sends the specif...
Debug-Process Cmdlet Microsoft.PowerShell.M... Debugs one or mo...
Get-Process Cmdlet Microsoft.PowerShell.M... Gets the process...
Get-WmiObject Cmdlet Microsoft.PowerShell.M... Gets instances o...
Start-Process Cmdlet Microsoft.PowerShell.M... Starts one or mo...
Stop-Process Cmdlet Microsoft.PowerShell.M... Stops one or mor...
Wait-Process Cmdlet Microsoft.PowerShell.M... Waits for the pr...
Get-Counter Cmdlet Microsoft.PowerShell.D... Gets performance...
Invoke-WSManAction Cmdlet Microsoft.WSMan.Manage... Invokes an actio...
Remove-WSManInstance Cmdlet Microsoft.WSMan.Manage... Deletes a manage...
Get-WSManInstance Cmdlet Microsoft.WSMan.Manage... Displays managem...
New-WSManInstance Cmdlet Microsoft.WSMan.Manage... Creates a new in...
Set-WSManInstance Cmdlet Microsoft.WSMan.Manage... Modifies the man...
about_Arithmetic_Operators HelpFile Describes the op...
about_Arrays HelpFile Describes arrays...
about_Debuggers HelpFile Describes the Wi...
about_Execution_Policies HelpFile Describes the Wi...
about_ForEach-Parallel HelpFile Describes the Fo...
about_Foreach HelpFile Describes a lang...
about_Functions HelpFile Describes how to...
about_Language_Keywords HelpFile Describes the ke...
about_Methods HelpFile Describes how to...
about_Objects HelpFile Provides essenti...
about_Parallel HelpFile Describes the Pa...
about_Pipelines HelpFile Combining comman...
about_Preference_Variables HelpFile Variables that c...
about_Remote HelpFile Describes how to...
about_Remote_Output HelpFile Describes how to...
about_Sequence HelpFile Describes the Se...
about_Session_Configuration_Files HelpFile Describes sessio...
about_Variables HelpFile Describes how va...
about_Windows_PowerShell_5.0 HelpFile Describes new fe...
about_WQL HelpFile Describes WMI Qu...
about_WS-Management_Cmdlets HelpFile Provides an over...
about_ForEach-Parallel HelpFile Describes the Fo...
about_Parallel HelpFile Describes the Pa...
about_Sequence HelpFile Describes the Se...
Using Help to search for process returned 10 results and using it to search for processes
returned 68 results. If only one result is found, the help topic itself will be displayed instead of
a list of commands.
get-help *hotfix*
NAME
Get-HotFix
SYNOPSIS
Gets the hotfixes that have been applied to the local and remote computers.
SYNTAX
Get-HotFix [-ComputerName <String[]>] [-Credential <PSCredential>] [-Description
<String[]>] [<CommonParameters>]
Get-HotFix [[-Id] <String[]>] [-ComputerName <String[]>] [-Credential
<PSCredential>] [<CommonParameters>]
DESCRIPTION
The Get-Hotfix cmdlet gets hotfixes (also called updates) that have been installed
on either the local computer (or on specified remote computers) by Windows Update,
Microsoft Update, or Windows Server Update Services; the cmdlet also gets hotfixes
or updates that have been installed manually by users.
RELATED LINKS
Online Version: http://go.microsoft.com/fwlink/?LinkId=821586
Win32_QuickFixEngineering http://go.microsoft.com/fwlink/?LinkID=145071
Get-ComputerRestorePoint
Add-Content
REMARKS
To see the examples, type: "get-help Get-HotFix -examples".
For more information, type: "get-help Get-HotFix -detailed".
For technical information, type: "get-help Get-HotFix -full".
For online help, type: "get-help Get-HotFix -online"
Now to debunk the myth that Help in PowerShell can only find commands that have help topics.
help *more*
NAME
more
SYNTAX
more [[-paths] <string[]>]
ALIASES
None
REMARKS
None
Notice in the previous example that more doesn't have a help topic, yet the Help system in
PowerShell was able to find it. It only found one match and returned the basic syntax information
that you'll see when a command doesn't have a help topic.
PowerShell contains numerous conceptual (About) help topics. The following command can be used to return a list of all About help topics on your system.
help About_*
Limiting the results to one single About help topic displays the actual help topic instead of returning a list.
help about_Updatable_Help
The help system in PowerShell has to be updated in order for the About help topics to be
present. If for some reason the initial update of the help system failed on your computer, the files
will not be available until the Update-Help cmdlet has been run successfully.
Get-Command
Get-Command is designed to help you locate commands. Running Get-Command without any parameters
returns a list of all the commands on your system. The following example demonstrates using the
Get-Command cmdlet to determine what commands exist for working with processes:
Get-Command -Noun Process
CommandType Name Version Source
----------- ---- ------- ------
Cmdlet Debug-Process 3.1.0.0 Microsof...
Cmdlet Get-Process 3.1.0.0 Microsof...
Cmdlet Start-Process 3.1.0.0 Microsof...
Cmdlet Stop-Process 3.1.0.0 Microsof...
Cmdlet Wait-Process 3.1.0.0 Microsof...
Notice in the previous example where Get-Command was run, the Noun parameter is used and
Process is specified as the value for the Noun parameter. What if you didn't know how to use
the Get-Command cmdlet? You could use Get-Help to display the help topic for Get-Command.
The Name, Noun, and Verb parameters accept wildcards. The following example shows wildcards being used with the Name parameter:
Get-Command -Name *service*
CommandType Name Version Source
----------- ---- ------- ------
Function Get-NetFirewallServiceFilter 2.0.0.0 NetSecurity
Function Set-NetFirewallServiceFilter 2.0.0.0 NetSecurity
Cmdlet Get-Service 3.1.0.0 Microsof...
Cmdlet New-Service 3.1.0.0 Microsof...
Cmdlet New-WebServiceProxy 3.1.0.0 Microsof...
Cmdlet Restart-Service 3.1.0.0 Microsof...
Cmdlet Resume-Service 3.1.0.0 Microsof...
Cmdlet Set-Service 3.1.0.0 Microsof...
Cmdlet Start-Service 3.1.0.0 Microsof...
Cmdlet Stop-Service 3.1.0.0 Microsof...
Cmdlet Suspend-Service 3.1.0.0 Microsof...
Application AgentService.exe 10.0.14... C:\Windo...
Application SensorDataService.exe 10.0.14... C:\Windo...
Application services.exe 10.0.14... C:\Windo...
Application services.msc 0.0.0.0 C:\Windo...
Application TieringEngineService.exe 10.0.14... C:\Windo...
I'm not a fan of using wildcards with the Name parameter of Get-Command since it also returns
executable files that are not native PowerShell commands.
If you are going to use wildcard characters with the Name parameter, I recommend limiting the results with the CommandType parameter.
Get-Command -Name *service* -CommandType Cmdlet, Function, Alias
A better option is to use either the Verb or Noun parameter or both of them since only PowerShell commands have both verbs and nouns.
Found something wrong with a help topic? The good news is the help topics for PowerShell have been open-sourced and available in the PowerShell-Docs repository on GitHub. Pay it forward by not only fixing the incorrect information for yourself, but everyone else as well. Simply fork the PowerShell documentation repository on GitHub, update the help topic, and submit a pull request. Once the pull request is accepted, the corrected documentation is available for everyone.
Updating Help
The local copy of the PowerShell help topics was previously updated the first-time help on a command
was requested. It's recommended to periodically update the help system because there can be updates
to the help content from time to time. The Update-Help cmdlet is used to update the help topics.
It requires internet access by default and for you to be running PowerShell elevated as an
administrator.
Update-Help
Update-Help : Failed to update Help for the module(s) 'BitsTransfer' with UI culture(s)
{en-US} : Unable to retrieve the HelpInfo XML file for UI culture en-US. Make sure the HelpInfoUri
property in the module manifest is valid or check your network connection and then try the command again.
At line:1 char:1
+ Update-Help
+
+ CategoryInfo : InvalidOperation: (:) [Update-Help], Exception
+ FullyQualifiedErrorId : InvalidHelpInfoUri,Microsoft.PowerShell.Commands.UpdateHel
pCommand
Update-Help : Failed to update Help for the module(s) 'NetworkControllerDiagnostics,
StorageReplica' with UI culture(s) {en-US} : Unable to retrieve the HelpInfo XML file
for UI culture en-US. Make sure the HelpInfoUri property in the module manifest is valid
or check your network connection and then try the command again.
At line:1 char:1
+ Update-Help
+
+ CategoryInfo : ResourceUnavailable: (:) [Update-Help], Exception
+ FullyQualifiedErrorId : UnableToRetrieveHelpInfoXml,Microsoft.PowerShell.Commands.
UpdateHelpCommand
A couple of the modules returned errors, which is not uncommon. If the machine didn't have internet
access, you could use the Save-Help cmdlet on another machine that does have internet access to
first save the updated help information to a file share on your network and then use the
SourcePath parameter of Update-Help to specify this network location for the help topics.
Consider setting up a scheduled task or adding some logic to your profile script in PowerShell to periodically update the help content on your computer. Profile scripts will be discussed in an upcoming chapter.
Summary
In this chapter you've learned how to find commands with both Get-Help and Get-Command. You've
learned how to use the help system to figure out how to use commands once you find them. You've also
learned how to update the content of the help topics when updates are available.
My challenge to you is to learn a PowerShell command a day.
Get-Command | Get-Random | Get-Help -Full
Review
- Is the DisplayName parameter of
Get-Servicepositional? - How many parameter sets does the
Get-Processcmdlet have? - What PowerShell commands exist for working with event logs?
- What is the PowerShell command for returning a list of PowerShell processes running on your computer?
- How do you update the PowerShell help content that's stored on your computer?
Recommended Reading
If you want to know more information about the topics covered in this chapter, I recommend reading the following PowerShell help topics.
In the next chapter, you'll learn about the Get-Member cmdlet as well as objects, properties, and
methods.
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