Get-CommandPath.ps1

<#
.SYNOPSIS
Locates a command.

.DESCRIPTION
Returns the full path to an application found in a directory in $env:Path,
optionally with an extension from $env:PathExt.

.INPUTS
System.String of commands to get the location details of.

.OUTPUTS
System.String of location details for the specified commands that were found.

.FUNCTIONALITY
Command

.LINK
Get-Command

.EXAMPLE
Get-CommandPath.ps1 powershell

C:\windows\System32\WindowsPowerShell\v1.0\powershell.exe

.EXAMPLE
Get-CommandPath.ps1 dotnet -FindAllInPath

C:\Program Files\dotnet\dotnet.exe
C:\Program Files (x86)\dotnet\dotnet.exe
#>

#Requires -Version 3
[CmdletBinding()][OutputType([string])] Param(
<#
The name of the executable program to look for in the $env:Path directories,
if the extension is omitted, $env:PathExt will be used to find one.
#>
[Parameter(Position=0,Mandatory=$true,ValueFromPipelineByPropertyName=$true)]
[Alias('Name','AN')][string[]] $ApplicationName,
# Indicates that every directory in the Path should be searched for the command.
[switch] $FindAllInPath
)
Process
{
    if($FindAllInPath)
    {
        $files =
            if((Split-Path $ApplicationName -Extension)) {$ApplicationName}
            else {$env:PATHEXT.ToLower() -split ';' |ForEach-Object {[io.path]::ChangeExtension($ApplicationName,$_)}}
        Write-Verbose "Searching Path for $($files -join ', ')"
        foreach($p in $env:Path -split ';')
        {
            $files |
                ForEach-Object {Join-Path $p $_} |
                Where-Object {Test-Path $_ -Type Leaf}
        }
    }
    else
    {
        foreach($cmd in Get-Command $ApplicationName)
        {
            if($cmd -is [Management.Automation.ApplicationInfo]) {$cmd.Path}
            elseif($cmd -is [Management.Automation.ExternalScriptInfo]) {$cmd.Path}
            elseif($cmd -is [Management.Automation.AliasInfo]) {$cmd.Definition}
            else {Write-Error "$ApplicationName is $($cmd.GetType().FullName)"}
        }
    }
}