PowerShell: The automatic variable $MyInvocation

Type of $myInvocation

The .NET framework type of $myInvocation is System.Management.Automation.InvocationInfo as can be demonstrated with

PS C:\> $myInvocation.getType().fullName

Properties of $myInvocation / InvocationInfo

Property	Comment	Misc
`MyCommand`	An object that inherits from `System.Management.Automation.CommandInfo` object. In the case of a script, it's a `System.Management.Automation.CommandInfo` or `System.Management.Automation.ExternalScriptInfo` object and `MyCommand.Name` evaluates to the filename of the current script, `MyCommand.Path` to its directory.	See also determining the name and directory of a PowerShell script within the script itself.
`BoundParameters`	a `System.Management.Automation.PSBoundParametersDictionary` object that stores the parameters that were bound for this script or command.
`UnboundArguments`	a `System.Collections.Generic.List<System.Object>` object that lists the arguments that were not bound to any parameter.
`ScriptLineNumber`	The line in the invoking script that contains the command being invoked
`OffsetInLine`
`HistoryId`
`ScriptName`	The name of the script that contains the cmdLet	What's the difference to `PSCommandPath`
`Line`	The text (of line `ScriptLineNumber`) that caused the invocation of the current command
`PositionMessage`
`PSScriptRoot`	The absolute path of the script that invoked the current command	Compare with the automatic variable `$psScriptRoot` which stores the absolute path of the script being invoked.
`PSCommandPath`	The absolute path to the directory where where the script is located that invoked the current command	Compare with the automatic variable `$psCommandPath` which stores the absolute path of the directory in which the script being invoked is located. What's the difference to `ScriptName`?
`InvocationName`
`PipelineLength`
`PipelinePosition`
`ExpectingInput`
`CommandOrigin`	A `System.Management.Automation.CommandOrigin` enum, either Runspace or Internal.
`DisplayScriptPosition`

Determining the name of a script

Arguably, one of the most interesting uses of $myInvocation is that it allows to determine the the name of a script within the script:

$scriptName = $myInvocation.myCommand.name

$myInvocation.myCommand.name always evaluates to a file name only, without any path components added to it, regardless if the script was invoked with a relative or absolute path name or from a different directory.

In order to get the full and absolute path name of a script, the expression $myInvocation.myCommand.path must be used.

Outside of a script, the expression $myInvocation.myCommand.path is $null.

Determining the directory in which a script is located

Another interesting case of $myInvocation is that it allows to determine the directory in which an script is located.

myInvocation.myCommand.path contains the full path (directory and script file name), therefore, in order to obtain the directory, the value of $myInvocation.mycommand.path must be passed to split-path:

$dir = split-path $myInvocation.myCommand.path

Compare this value with that of $psScriptRoot

Script to demonstrate some values of myInvocation

The following script is intended to display some values the properties of $myInvocation. The script body calls the function func-1 which calls the function func-2.

The script body as well as the functions print the (imho) interesting values:

function func-2 {

#  write-host "`$myInvocation.GetType().FullName           = $($myinvocation.GetType().FullName)"
   write-host "`$myInvocation.myCommand.GetType().FullName = $($myinvocation.myCommand.GetType().FullName)"
   write-host "`$myInvocation.myCommand.name               = $($myinvocation.myCommand.name)"
#  write-host "`$myInvocation.myCommand.path               = $($myinvocation.myCommand.path)"
   write-host "`$myInvocation.scriptName                   = $($myinvocation.scriptName)"
   write-host "`$myInvocation.psScriptRoot                 = $($myinvocation.psScriptRoot)"
   write-host "`$myInvocation.psCommandPath                = $($myinvocation.psCommandPath)"
   write-host "`$myInvocation.commandOrigin                = $($myinvocation.commandOrigin)"

}

function func-1 {

#  write-host "`$myInvocation.GetType().FullName           = $($myinvocation.GetType().FullName)"
   write-host "`$myInvocation.myCommand.GetType().FullName = $($myinvocation.myCommand.GetType().FullName)"
   write-host "`$myInvocation.myCommand.name               = $($myinvocation.myCommand.name)"
#  write-host "`$myInvocation.myCommand.path               = $($myinvocation.myCommand.path)"
   write-host "`$myInvocation.scriptName                   = $($myinvocation.scriptName)"
   write-host "`$myInvocation.psScriptRoot                 = $($myinvocation.psScriptRoot)"
   write-host "`$myInvocation.psCommandPath                = $($myinvocation.psCommandPath)"
   write-host "`$myInvocation.commandOrigin                = $($myinvocation.commandOrigin)"

   write-host

   func-2

}

#  write-host "`$myInvocation.GetType().FullName           = $($myinvocation.GetType().FullName)"
   write-host "`$myInvocation.myCommand.GetType().FullName = $($myinvocation.myCommand.GetType().FullName)"
   write-host "`$myInvocation.myCommand.name               = $($myinvocation.myCommand.name)"
   write-host "`$myInvocation.myCommand.path               = $($myinvocation.myCommand.path)"
   write-host "`$myInvocation.scriptName                   = $($myinvocation.scriptName)"
   write-host "`$myInvocation.psScriptRoot                 = $($myinvocation.psScriptRoot)"
   write-host "`$myInvocation.psCommandPath                = $($myinvocation.psCommandPath)"
   write-host "`$myInvocation.commandOrigin                = $($myinvocation.commandOrigin)"

write-host

func-1

Github repository about-PowerShell, path: /language/variable/automatic/myInvocation/script.ps1