TOPIC
about_Comment_Based_Help
SHORT DESCRIPTION
Describes how to write comment-based Help topics for Functions and scripts.
LONG DESCRIPTION
You can write comment-based Help topics for Functions and scripts by using
special Help comment keywords.
The Get-Help cmdlet displays comment-based Help in the same format in which
it displays the cmdlet Help topics that are generated from XML files. Users
can use all of the parameters of Get-Help, such as Detailed, Full, Example,
and Online, to display Function and script Help.
You can also write XML-based Help files for scripts and Functions by using
Help comment keywords, and you can redirect users to a different Help file.
This topic explains how to write Help topics for Functions and scripts. For
information about how to display Help topics for Functions and scripts, see
Get-Help.
SYNTAX FOR COMMENT-BASED HELP
The syntax for comment-based Help is as follows:
# .< help keyword>
# <help content>
-or –
<#
.< help keyword>
< help content>
#>
Comment-based Help is written as a series of comments. You can type a
comment symbol (#) before each line of comments, or you can use the “<#” and “#>”
symbols to create a comment block. All the lines within the comment block are
interpreted as comments.
All of the lines in a comment-based Help topic must be contiguous. If a
comment-based Help topic follows a comment that is not part of the Help
topic, there must be at least one blank line between the last non-Help
comment line and the beginning of the comment-based Help.
Keywords define each section of comment-based Help. Each comment-based Help
keyword is preceded by a dot (.). The keywords can appear in any order. The
keyword names are not case-sensitive.
For example, the Description keyword precedes a description of a Function or
script.
<#
.Description
Get-Function displays the name and syntax of all Functions in the session.
#>
The comment block must contain at least one keyword. Some of the keywords,
such as EXAMPLE, can appear many times in the same comment block. The Help
content for each keyword begins on the line after the keyword and can span
multiple lines.
SYNTAX FOR COMMENT-BASED HELP IN FunctionS
Comment-based Help for a Function can appear in one of three locations:
— At the beginning of the Function body.
— At the end of the Function body.
— Before the Function keyword. There cannot be more than one blank
line between the last line of the Function Help and the Function
keyword.
For example:
Function MyFunction
{
<#
.< help keyword>
< help content>
#>
<function commands>
}
-or –
Function MyFunction
{
<function commands>
<#
.< help keyword>
< help content>
#>
}
-or –
<#
.< help keyword>
< help content>
#>
Function MyFunction { }
SYNTAX FOR COMMENT-BASED HELP IN SCRIPTS
Comment-based Help for a script can appear in one of the following two
locations in the script.
— At the beginning of the script file. Script Help can be preceded in the
script only by comments and blank lines.
— If the first item in the script body (after the Help) is a Function
declaration, there must be at least two blank lines between the end of the
script Help and the Function declaration. Otherwise, the Help is
interpreted as being Help for the Function, not Help for the script.
— At the end of the script file.
For example:
<#
.< help keyword>
< help content>
#>
Function MyFunction { }
-or-
Function MyFunction { }
<#
.< help keyword>
< help content>
#>
COMMENT-BASED HELP KEYWORDS
The following are valid comment-based Help keywords. They are listed in the order in
which they typically appear in a Help topic along with their intended use.
These keywords can appear in any order in the comment-based Help, and they
are not case-sensitive.
.SYNOPSIS
A brief description of the Function or script. This keyword can be used
only once in each topic.
.DESCRIPTION
A detailed description of the Function or script. This keyword can be
used only once in each topic.
.PARAMETER <Parameter-Name>
The description of a parameter. You can include a Parameter keyword for
each parameter in the Function or script syntax.
The Parameter keywords can appear in any order in the comment block, but
the Function or script syntax determines the order in which the parameters
(and their descriptions) appear in Help topic. To change the order,
change the syntax.
You can also specify a parameter description by placing a comment in the
Function or script syntax immediately before the parameter Variable name.
If you use both a syntax comment and a Parameter keyword, the description
associated with the Parameter keyword is used, and the syntax comment is
ignored.
.EXAMPLE
A sample command that uses the Function or script, optionally followed
by sample output and a description. Repeat this keyword for each example.
.INPUTS
The Microsoft .NET Framework types of objects that can be piped to the
Function or script. You can also include a description of the input
objects.
.OUTPUTS
The .NET Framework type of the objects that the cmdlet returns. You can
also include a description of the returned objects.
.NOTES
Additional information about the Function or script.
.LINK
The name of a related topic. Repeat this keyword for each related topic.
This content appears in the Related Links section of the Help topic.
The Link keyword content can also include a Uniform Resource Identifier
(URI) to an online version of the same Help topic. The online version
opens when you use the Online parameter of Get-Help. The URI must begin
with “http” or “https”.
.COMPONENT
The technology or feature that the Function or script uses, or to which
it is related. This content appears when the Get-Help command includes
the Component parameter of Get-Help.
.ROLE
The user role for the Help topic. This content appears when the Get-Help
command includes the Role parameter of Get-Help.
.FUNCTIONALITY
The intended use of the Function. This content appears when the Get-Help
command includes the Functionality parameter of Get-Help.
.FORWARDHELPTARGETNAME <Command-Name>
Redirects to the Help topic for the specified command. You can redirect
users to any Help topic, including Help topics for a Function, script,
cmdlet, or provider.
.FORWARDHELPCATEGORY <Category>
Specifies the Help category of the item in ForwardHelpTargetName.
Valid values are Alias, Cmdlet, HelpFile, Function, Provider, General,
FAQ, Glossary, ScriptCommand, ExternalScript, Filter, or All. Use this
keyword to avoid conflicts when there are commands with the same name.
.REMOTEHELPRUNSPACE <PSSession-variable>
Specifies a session that contains the Help topic. Enter a Variable that
contains a PSSession. This keyword is used by the Export-PSSession
cmdlet to find the Help topics for the exported commands.
.EXTERNALHELP <XML Help File Path>
Specifies the path to an XML-based Help file for the script or Function.
In Windows Vista and later versions of Windows, if the specified path
to the XML file contains UI-culture-specific subdirectories, Get-Help
searches the subdirectories recursively for an XML file with the name
of the script or Function in accordance with the language fallback
standards established for Windows Vista, just as it does for all
XML-based Help topics.
For more information about the cmdlet Help XML-based Help file format,
see “How to Create Cmdlet Help” in the MSDN (Microsoft Developer Network)
library at http://go.microsoft.com/fwlink/?LinkID=123415.
AUTOGENERATED CONTENT
The name, syntax, parameter list, parameter attribute table, common
parameters, and remarks are automatically generated by the Get-Help cmdlet.
Name:
The Name section of a Function Help topic is taken from the Function
name in the Function syntax. The Name of a script Help topic is
taken from the script file name. To change the name or its
capitalization, change the Function syntax or the script file name.
Syntax:
The Syntax section of the Help topic is generated from the Function
or script syntax. To add detail to the Help topic syntax, such as
the .NET Framework type of a parameter, add the detail to the syntax.
If you do not specify a parameter type, the “Object” type is
inserted as the default value.
Parameter List:
The Parameter list in the Help topic is generated from the Function
or script syntax and from the descriptions that you add by using the
Parameters keyword. The Function parameters appear in the “Parameters”
section of the Help topic in the same order that they appear in
the Function or script syntax. The spelling and capitalization of
parameter names is also taken from the syntax; it is not affected
by the parameter name specified by the Parameter keyword.
Common Parameters:
The common parameters are added to the syntax and parameter list
of the Help topic, even if they have no effect. For more information
about the common parameters, see about_CommonParameters.
Parameter Attribute Table:
Get-Help generates the table of parameter attributes that appears
when you use the Full or Parameter parameter of Get-Help. The value
of the Required, Position, and Default value attributes is taken
from the Function or script syntax.
Remarks:
The Remarks section of the Help topic is automatically generated
from the Function or script name. You cannot change or affect its
content.
EXAMPLES
Example 1: Comment-based Help for a Function
The following sample Function includes comment-based Help:
Function Add-Extension
{
param ([string]$Name,[string]$Extension = “txt”)
$name = $name + “.” + $extension
$name
<#
.SYNOPSIS
Adds a file name extension to a supplied name.
.DESCRIPTION
Adds a file name extension to a supplied name.
Takes any strings for the file name or extension.
.PARAMETER Name
Specifies the file name.
.PARAMETER Extension
Specifies the extension. “Txt” is the default.
.INPUTS
None. You cannot pipe objects to Add-Extension.
.OUTPUTS
System.String. Add-Extension returns a string with the extension or file name.
.EXAMPLE
C:\PS> extension -name “File”
File.txt
.EXAMPLE
C:\PS> extension -name “File” -extension “doc”
File.doc
.EXAMPLE
C:\PS> extension “File” “doc”
File.doc
.LINK
Online version: http://www.fabrikam.com/extension.html
.LINK
Set-Item
#>
}
The results are as follows:
C:\PS> Get-Help add-extension -full
NAME
Add-Extension
SYNOPSIS
Adds a file name extension to a supplied name.
SYNTAX
Add-Extension [[-Name] <String>] [[-Extension] <String>] [<CommonParameters>]
DESCRIPTION
Adds a file name extension to a supplied name. Takes any strings for the file name or extension.
PARAMETERS
-Name
Specifies the file name.
Required? false
Position? 0
Default value
Accept pipeline input? false
Accept wildcard characters?
-Extension
Specifies the extension. “Txt” is the default.
Required? false
Position? 1
Default value
Accept pipeline input? false
Accept wildcard characters?
<CommonParameters>
This cmdlet supports the common parameters: -Verbose, -Debug,
-ErrorAction, -ErrorVariable, -WarningAction, -WarningVariable,
-OutBuffer and -OutVariable. For more information, type
“Get-Help about_CommonParameters“.
INPUTs
None. You cannot pipe objects to Add-Extension.
OUTPUTS
System.String. Add-Extension returns a string with the extension or file name.
————————– EXAMPLE 1 ————————–
C:\PS> extension -name “File”
File.txt
————————– EXAMPLE 2 ————————–
C:\PS> extension -name “File” -extension “doc”
File.doc
————————– EXAMPLE 3 ————————–
C:\PS> extension “File” “doc”
File.doc
RELATED LINKS
Online version: http://www.fabrikam.com/extension.html
Set-Item
Example 2: Parameter Descriptions in Function Syntax
This example is the same as the previous one, except that the parameter
descriptions are inserted in the Function syntax. This format is most
useful when the descriptions are brief.
Function Add-Extension
{
param
(
[string]
# Specifies the file name.
$name,
[string]
# Specifies the file name extension. “Txt” is the default.
$extension = “txt”
)
$name = $name + “.” + $extension
$name
<#
.SYNOPSIS
Adds a file name extension to a supplied name.
.DESCRIPTION
Adds a file name extension to a supplied name. Takes any strings for the file name or extension.
.INPUTS
None. You cannot pipe objects to Add-Extension.
.OUTPUTS
System.String. Add-Extension returns a string with the extension or file name.
.EXAMPLE
C:\PS> extension -name “File”
File.txt
.EXAMPLE
C:\PS> extension -name “File” -extension “doc”
File.doc
.EXAMPLE
C:\PS> extension “File” “doc”
File.doc
.LINK
Online version: http://www.fabrikam.com/extension.html
.LINK
Set-Item
#>
}
Example 3: Comment-based Help for a Script
The following sample script includes comment-based Help.
Notice the blank lines between the closing “#>” and the Param statement.
In a script that does not have a Param statement, there must be at least
two blank lines between the final comment in the Help topic and the first
Function declaration. Without these blank lines, Get-Help associates the
Help topic with the Function, not the script.
<#
.SYNOPSIS
Performs monthly data updates.
.DESCRIPTION
The Update-Month.ps1 script updates the Registry with new data generated
during the past month and generates a report.
.PARAMETER InputPath
Specifies the path to the CSV-based input file.
.PARAMETER OutputPath
Specifies the name and path for the CSV-based output file. By default,
MonthlyUpdates.ps1 generates a name from the date and time it runs, and
saves the output in the local directory.
.INPUTS
None. You cannot pipe objects to Update-Month.ps1.
.OUTPUTS
None. Update-Month.ps1 does not generate any output.
.EXAMPLE
C:\PS> .\Update-Month.ps1
.EXAMPLE
C:\PS> .\Update-Month.ps1 -inputpath C:\Data\January.csv
.EXAMPLE
C:\PS> .\Update-Month.ps1 -inputpath C:\Data\January.csv -outputPath C:\Reports\2009\January.csv
#>
param ([string]$InputPath, [string]$OutPutPath)
Function Get-Data { }
…
The following command gets the script Help. Because the script is not
in a directory that is listed in the Path Environment Variable, the
Get-Help command that gets the script Help must specify the script path.
PS C:\ps-test> Get-Help .\update-month.ps1 -full
NAME
C:\ps-test\Update-Month.ps1
SYNOPSIS
Performs monthly data updates.
SYNTAX
C:\ps-test\Update-Month.ps1 [-InputPath] <String> [[-OutputPath]
<String>] [<CommonParameters>]
DESCRIPTION
The Update-Month.ps1 script updates the Registry with new data
generated during the past month and generates a report.
PARAMETERS
-InputPath
Specifies the path to the CSV-based input file.
Required? true
Position? 0
Default value
Accept pipeline input? false
Accept wildcard characters?
-OutputPath
Specifies the name and path for the CSV-based output file. By
default, MonthlyUpdates.ps1 generates a name from the date
and time it runs, and saves the output in the local directory.
Required? false
Position? 1
Default value
Accept pipeline input? false
Accept wildcard characters?
<CommonParameters>
This cmdlet supports the common parameters: -Verbose, -Debug,
-ErrorAction, -ErrorVariable, -WarningAction, -WarningVariable,
-OutBuffer and -OutVariable. For more information, type,
“Get-Help about_CommonParameters“.
INPUTS
None. You cannot pipe objects to Update-Month.ps1.
OUTPUTS
None. Update-Month.ps1 does not generate any output.
————————– EXAMPLE 1 ————————–
C:\PS> .\Update-Month.ps1
————————– EXAMPLE 2 ————————–
C:\PS> .\Update-Month.ps1 -inputpath C:\Data\January.csv
————————– EXAMPLE 3 ————————–
C:\PS> .\Update-Month.ps1 -inputpath C:\Data\January.csv -outputPath
C:\Reports\2009\January.csv
RELATED LINKS
Example 4: Redirecting to an XML File
You can write XML-based Help topics for Functions and scripts. Although
comment-based Help is easier to implement, XML-based Help is required
if you want more precise control over Help content or if you are
translating Help topics into multiple languages.
The following example shows the first few lines of the Update-Month.ps1
script. The script uses the ExternalHelp keyword to specify the path to
an XML-based Help topic for the script.
# .ExternalHelp C:\MyScripts\Update-Month-Help.xml
param ([string]$InputPath, [string]$OutPutPath)
Function Get-Data { }
…
The following example shows the use of the ExternalHelp keyword in a
Function.
Function Add-Extension
{
param ([string] $name, [string]$extension = “txt”)
$name = $name + “.” + $extension
$name
# .ExternalHelp C:\ps-test\Add-Extension.xml
}
Example 5: Redirecting to a Different Help Topic
The following code is an excerpt from the beginning of the built-in
Help Function in Windows PowerShell, which displays one screen of Help
text at a time. Because the Help topic for the Get-Help cmdlet describes
the Help Function, the Help Function uses the ForwardHelpTargetName and
ForwardHelpCategory keywords to redirect the user to the Get-Help cmdlet
Help topic.
Function help
{
<#
.FORWARDHELPTARGETNAME Get-Help
.FORWARDHELPCATEGORY Cmdlet
#>
[CmdletBinding(DefaultParameterSetName=’AllUsersView’)]
param(
[Parameter(Position=0, ValueFromPipelineByPropertyName=$true)]
[System.String]
${Name},
…
The following command uses this feature:
C:\PS> Get-Help help
NAME
Get-Help
SYNOPSIS
Displays information about Windows PowerShell cmdlets and concepts.
…
SEE ALSO
about_functions
about_functions_advanced_parameters
about_scripts
“How to Write Cmdlet Help” (http://go.microsoft.com/fwlink/?LinkID=123415)