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This is the built-in help made by Microsoft for the document 'about_Parameters', in PowerShell version 5 - as retrieved from Windows version 'Microsoft Windows Server 2012 R2 Standard' PowerShell help files on 2016-06-24.

For PowerShell version 3 and up, where you have Update-Help, this command was run just before creating the web pages from the help files.

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Describes how to work with command parameters in Windows PowerShell.

Most Windows PowerShell commands, such as cmdlets, functions, and scripts,
rely on parameters to allow users to select options or provide input. The
parameters follow the command name and have the following form:

-<parameter_name> <parameter_value>

The name of the parameter is preceded by a hyphen (-), which signals to
Windows PowerShell that the word following the hyphen is a parameter name.
Some parameters do not require or accept a parameter value. Other parameters
require a value, but do not require the parameter name in the command.

The type of parameters and the requirements for those parameters vary. To
find information about the parameters of a command, use the Get-Help cmdlet.
For example, to find information about the parameters of the Get-ChildItem
cmdlet, type:

Get-Help Get-ChildItem

To find information about the parameters of a script, use the full path to
the script file. For example:

Get-Help $home\Documents\Scripts\Get-Function.ps1

The Get-Help cmdlet returns various details about the command, including a
description, the command syntax, information about the parameters, and examples
showing how to use the parameters in a command.

You can also use the Parameter parameter of the Get-Help cmdlet to find
information about a particular parameter. Or, you can use the Parameter parameter
with the wildcard character (*) value to find information about all parameters
of the command. For example, the following command gets information about all
parameters of the Get-Member cmdlet:

Get-Help Get-Member -Parameter *

Optional parameters have a default value, which is the value that is used
or assumed when the parameter is not specified in the command.

For example, the default value of the ComputerName parameter of many cmdlets
is the name of the local computer. As a result, the local computer name is
used in the command unless the ComputerName parameter is specified.

To find the default parameter value, see help topic for the cmdlet. The
parameter description should include the default value.

You can also set a custom default value for any parameter of a cmdlet or
advanced function. For information about setting custom default values, see


When you use the Full, Parameter, or Online parameters of the Get-Help cmdlet,
Get-Help displays a parameter attribute table with detailed information
about the parameter.

This information includes the details you need to know to use the
parameter. For example, the help topic for the Get-ChildItem cmdlet
includes the following details about its Path parameter:

-path <string[]>
Specifies a path of one or more locations. Wildcard characters are
permitted. The default location is the current directory (.).

Required? false
Position? 1
Default value Current directory
Accept pipeline input? true (ByValue, ByPropertyName)
Accept wildcard characters? true

The parameter information includes the parameter syntax,
a description of the parameter, and the parameter attributes.
The following sections describe the parameter attributes.

Parameter Required?
This setting indicates whether the parameter is mandatory, that
is, whether all commands that use this cmdlet must include this
parameter. When the value is "True" and the parameter is missing
from the command, Windows PowerShell prompts you for a value for
the parameter.

Parameter Position?
This setting indicates whether you can supply a parameter's value
without preceding it with the parameter name. If set to "0" or "named,"
a parameter name is required. This type of parameter is referred to as
a named parameter. A named parameter can be listed in any position
after the cmdlet name.

If the "Parameter position?" setting is set to an integer other than 0,
the parameter name is not required. This type of parameter is referred
to as a positional parameter, and the number indicates the position
in which the parameter must appear in relation to other positional
parameters. If you include the parameter name for a positional
parameter, the parameter can be listed in any position after the
cmdlet name.

For example, the Get-ChildItem cmdlet has Path and Exclude parameters.
The "Parameter position?" setting for Path is 1, which means that it
is a positional parameter. The "Parameter position?" setting for Exclude
is 0, which means that it is a named parameter.

This means that Path does not require the parameter name, but its
parameter value must be the first or only unnamed parameter value
in the command. However, because the Exclude parameter is a named

parameter, you can place it in any position in the command.

As a result of the "Parameter position?" settings for these two
parameters, you can use any of the following commands:

Get-ChildItem -path c:\techdocs -exclude *.ppt
Get-ChildItem c:\techdocs -exclude *.ppt
Get-ChildItem -exclude *.ppt -path c:\techdocs
Get-ChildItem -exclude *.ppt c:\techdocs

If you were to include another positional parameter without including
the parameter name, that parameter would have to be placed in the order
specified by the "Parameter position?" setting.

Parameter Type
This setting specifies the Microsoft .NET Framework type of the parameter
value. For example, if the type is Int32, the parameter value must be an
integer. If the type is string, the parameter value must be a
character string. If the string contains spaces, the value must be
enclosed in quotation marks, or the spaces must be preceded by the
escape character (`).

Default Value
This setting specifies the value that the parameter will assume
if no other value is provided. For example, the default value of
the Path parameter is often the current directory. Required
parameters never have a default value. For many optional parameters,
there is no default because the parameter has no effect if it is
not used.

Accepts Multiple Values?
This setting indicates whether a parameter accepts multiple
parameter values. When a parameter accepts multiple values,
you can type a comma-separated list as the value of the parameter
in the command, or save a comma-separated list (an array) in a
variable, and then specify the variable as the parameter value.

For example, the ServiceName parameter of the Get-Service
cmdlet accepts multiple values. The following commands are both valid:

get-service -servicename winrm, netlogon

$s = "winrm", "netlogon"
get-service -servicename $s

Accepts Pipeline Input?
This setting indicates whether you can use the pipeline operator
(|) to send a value to the parameter.

Value Description
----- -----------
False Indicates that you cannot pipe a value to the

True (by Value) Indicates that you can pipe any value to the
parameter, just so the value has the .NET
Framework type specified for the parameter or the
value can be converted to the specified .NET
Framework type.

When a parameter is "True (by Value)", Windows
PowerShell tries to associate any piped values
with that parameter before it tries other methods
to interpret the command.

True (by Property Name) Indicates that you can pipe a value to the
parameter, but the .NET Framework type of the
parameter must include a property with the same
name as the parameter.

For example, you can pipe a value to a Name
parameter only when the value has a property
called "Name".

Accepts Wildcard Characters?
This setting indicates whether the parameter's value can contain
wildcard characters so that the parameter value can be matched to more
than one existing item in the target container.

Common Parameters
Common parameters are parameters that you can use with any cmdlet.
For more information about common parameters, see about_CommonParameters