Install-PowerShell

Install-PowerShell.ps1

function Install-PowerShell {
<#
.SYNOPSIS
    Installs latest PowerShell 7 via msi, from GitHub.
    You need to:
      a) run this from PS 5 (not PS 7) on windows (not linux)
      b) have internet connectivity (and able to access github.com)
      c) and have rights to install apps (usually local admin privileges)
.EXAMPLE
    Install-PowerShell -Verbose
.NOTES
    Author: Panos Grigoriadis
    Date:   15/10/2021
#>
[OutputType([System.Void])]
[OutputType([System.Boolean], ParameterSetName='OutBool')]
[OutputType([Microsoft.PackageManagement.Packaging.SoftwareIdentity], ParameterSetName='OutObject')]
[CmdletBinding(DefaultParameterSetName='__AllParameterSets')]
param (
    [int]$Timeout = 5, # in minutes
    [Parameter(ParameterSetName='OutBool')]
    [switch]$Quiet,    # [bool] output
    [Parameter(ParameterSetName='OutObject')]
    [switch]$PassThru  # [psobject] output
)
$PSDefaultParameterValues = @{'Remove-Job:Verbose' = $false}

$IsWinPS = $PSVersionTable.PSVersion.Major -eq 5
if (-not $IsWinPS) {
    return 'Please run this from Windows PowerShell 5.x, not from PowerShell 6+'
    # that's because if you run this on PS7, you can't update its own process
}

# create a PS job for the installation
$timer = [Diagnostics.StopWatch]::StartNew()
$block = {
    $PSDefaultParameterValues = @{
        'Invoke-RestMethod:Verbose' = $false
        'Start-Process:Verbose'     = $false
    }
    $ErrorActionPreference = 'Stop'
    try {
        $repo = 'PowerShell/PowerShell'
        $url  = "https://api.github.com/repos/$repo/releases/latest"
        $ass  = (Invoke-RestMethod $url).assets_url
        $all  = (Invoke-RestMethod $ass).browser_download_url
        $msi  = $all | where {$_ -like '*win-x64.msi'}
        $cmd  = "/package $msi /quiet REGISTER_MANIFEST=1" # ENABLE_PSREMOTING=1
        Start-Process msiexec.exe -Wait -ArgumentList $cmd
    }
    catch {throw $_}
}
Write-Verbose 'Starting installation'
$job = Start-Job -ScriptBlock $block

# wait for the install to finish
$every = (10,30,60,120,240) ; $i = 0  # <-- exponential back-off on the wait feedback
$StartTime = Get-Date ; $TimeoutExpired = $false ; $IsDone = $false
while (-not $IsDone -and -not $TimeoutExpired) {
    $Elapsed = (Get-Date) - $StartTime
    $TimeoutExpired = $Elapsed.TotalMinutes -gt $Timeout
    if ($TimeoutExpired) {Write-Warning 'Timeout expired';break}
    
    $sec = $Elapsed.TotalSeconds ; $dur = $Elapsed.ToString('mm\:ss')
    $chk = $sec % $every[$i] ; $wait = 5 # in seconds
    if ($chk -lt $sec -and $chk -le $wait -and $sec -ge $wait) {
        $i++
        Write-Verbose "Wait for install to finish [$dur]"
    }
    Start-Sleep -Seconds $wait
    $IsDone = $job.State -eq 'Completed' -or $job.State -eq 'Failed'
    $job    = Get-Job -Id $job.Id
}

# prepare some variables for the output
if ($job.State -eq 'Failed')    {$Err = $job.ChildJobs[0].JobStateInfo.Reason.ErrorRecord}
if ($job.State -eq 'Completed') {$Pkg = Get-Package -ProviderName msi | where Name -like 'PowerShell*'}
# Note: Get-Package only works on PS5, not PS6 or PS7, cause it can't access the msi provider (as of yet)
# Note: To get all job states [Enum]::GetNames([System.Management.Automation.JobState])
$job | Remove-Job -Force -ErrorAction Ignore
$timer.Stop()
$total   = $timer.Elapsed.ToString('mm\:ss')
$Complet = $job.State -eq 'Completed'
$Failed  = $job.State -eq 'Failed'
$NotDone = $job.State -NotMatch 'Completed|Failed'
$HasPkg  = $Pkg -as [bool]
$OutObj  = $PassThru.IsPresent


# finally show the output
if ($Complet -and  $HasPkg)               {Write-Verbose "Installed successfully! [$total]"}
if ($Complet -and  $HasPkg -and  $Quiet)  {Write-Output $true}
if ($Complet -and  $HasPkg -and  $OutObj) {Write-Output $Pkg}
if ($Complet -and !$HasPkg -and !$Quiet)  {Write-Warning 'PowerShell was NOT found on the system!'}
if ($Complet -and !$HasPkg -and  $Quiet)  {Write-Output $false}
if ($Failed  -and !$Quiet)                {Write-Error -ErrorRecord $Err}
if ($Failed  -and  $Quiet)                {Write-Output $false}
if ($NotDone -and !$Quiet)                {Write-Warning 'Could NOT install PowerShell'}
if ($NotDone -and  $Quiet)                {Write-Output $false}

}