All 3 backups finished.
' Start-Process -FilePath .\report.html ``` Nothing prints; your web browser opens the page. A folder works the same way: `Start-Process -FilePath .` opens File Explorer on the folder you're in (`.` is read "here"). To choose the app yourself, name the program and give it the file in **`-ArgumentList`**, the list of things to hand the program as it starts: ```powershell Start-Process -FilePath notepad -ArgumentList .\report.html ``` Notepad opens with the page's text in it. `Invoke-Item` (short name `ii`) also opens a file in its own app. ## Starting a program, and keeping its Id Make a pretend backup that takes six seconds: ```powershell Set-Content -Path backup.ps1 -Value '# backup.ps1: pretends to back up three folders, two seconds each.', "foreach (`$folder in 'Documents', 'Pictures', 'Music') {", ' Write-Output "Backing up $folder..."', ' Start-Sleep -Seconds 2', '}', "Write-Output 'Backup done.'" ``` (The backtick in front of `$folder` keeps that one `$` as it is inside double quotes.) Start it as its own PowerShell, with no window, and ask for the process back: ```powershell Start-Process -FilePath pwsh -ArgumentList '-NoProfile', '-File', '.\backup.ps1' -WindowStyle Hidden -PassThru ``` ```text NPM(K) PM(M) WS(M) CPU(s) Id SI ProcessName ------ ----- ----- ------ -- -- ----------- 9 1.64 7.70 0.02 67468 1 pwsh ``` Three parameters do the work: - **`-ArgumentList`** is everything after the program's name, as a list: `pwsh -NoProfile -File .\backup.ps1`. - **`-WindowStyle Hidden`** starts it with no window. `Minimized` and `Maximized` work too. - **`-PassThru`** hands back the process. Without it, `Start-Process` prints nothing, and a hidden program can get lost; you'd be hunting for it as in *What's Running: `Get-Process` and `Stop-Process`*. ## Waiting for it to finish The prompt came back at once, while the backup carried on. To wait for it now, give its Id to **`Wait-Process`**. It returns when the program ends, and then the process is gone: ```powershell Wait-Process -Id 67468 Get-Process -Id 67468 ``` ```text Get-Process: Cannot find a process with the process identifier 67468. ``` When you know from the start that the next step must wait, use **`-Wait`**. Add `-NoNewWindow` and the program prints into this window. Keep the process in a variable with `-PassThru`, and its **ExitCode** tells you how it went: ```powershell $backup = Start-Process -FilePath pwsh -ArgumentList '-NoProfile', '-File', '.\backup.ps1' -NoNewWindow -Wait -PassThru $backup.ExitCode ``` ```text Backing up Documents... Backing up Pictures... Backing up Music... Backup done. 0 ``` An exit code of 0 means it worked; any other number means something went wrong, as *Did It Work? `$?`, `$LASTEXITCODE`, `&&` and `||`* showed. An install script checks it before going on. ## As administrator: -Verb RunAs An **administrator** may change anything on the computer: install apps for everyone, restart Windows' services, change other people's settings. Your PowerShell window doesn't use those rights unless you ask, and that's on purpose: one wrong command can't damage the whole PC. **User Account Control** (UAC) is the box that asks first. `-Verb RunAs` asks for a new PowerShell as administrator: ```powershell Start-Process -FilePath pwsh -Verb RunAs ``` Run that only when a job needs it. Windows dims the screen and asks *Do you want to allow this app to make changes to your device?* If you choose Yes, a new window opens whose title starts with *Administrator:*. Everything typed there can change the whole computer, so do the one job and close it. You can check which kind of window you're in; this line asks Windows about the account you're using in it: ```powershell $me = [Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent() $me.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator) ``` ```text False ``` `False`: an ordinary window, the right one for nearly everything. **On a Mac or Linux**, `Start-Process` opens files in their apps too, but `-Verb`, `-WindowStyle` and `-NoNewWindow` don't apply there; `sudo` is how a command gets administrator rights. Windows PowerShell 5.1 has the same `Start-Process`. ## Check yourself 2 questions to try on the lesson page. ## So what `Start-Process` starts a program the way the job needs it: in its own app, out of sight, waited for, or as administrator, and `-PassThru` keeps hold of it so it never gets lost. ## Key terms - [Start-Process](https://www.ask-codey.com/glossary/start-process) - [Administrator](https://www.ask-codey.com/glossary/administrator) - [User Account Control](https://www.ask-codey.com/glossary/user-account-control) - [Exit Code](https://www.ask-codey.com/glossary/exit-code-operating-system) ## Cheat sheets - [Starting Programs: \`Start-Process\`](https://www.ask-codey.com/cheat-sheets/powershell-start-process-cheat-sheet) ## Related - [What's Running: \`Get-Process\` and \`Stop-Process\`](https://www.ask-codey.com/lessons/powershell-processes) - [Background Jobs and Parallel Work](https://www.ask-codey.com/lessons/powershell-jobs) - [Run It from Anywhere](https://www.ask-codey.com/lessons/powershell-run-from-anywhere) - [Did It Work? \`$?\`, \`$LASTEXITCODE\`, \`&&\` and \`||\`](https://www.ask-codey.com/lessons/powershell-did-it-work) Source: https://www.ask-codey.com/lessons/powershell-start-process