Powershell test for noninteractive mode - powershell

Question

I have a script that may be run manually or may be run by a scheduled task. I need to programmatically determine if I'm running in -noninteractive mode (which is set when run via scheduled task) or normal mode. I've googled around and the best I can find is to add a command line parameter, but I don't have any feasible way of doing that with the scheduled tasks nor can I reasonably expect the users to add the parameter when they run it manually.
Does noninteractive mode set some kind of variable or something I could check for in my script?
Edit:
I actually inadvertently answered my own question but I'm leaving it here for posterity.
I stuck a read-host in the script to ask the user for something and when it ran in noninteractive mode, boom, terminating error. Stuck it in a try/catch block and do stuff based on what mode I'm in.
Not the prettiest code structure, but it works. If anyone else has a better way please add it!

Answer 1

I didn't like any of the other answers as a complete solution. [Environment]::UserInteractive reports whether the user is interactive, not specifically if the process is interactive. The api is useful for detecting if you are running inside a service. Here's my solution to handle both cases:
function Assert-IsNonInteractiveShell {
# Test each Arg for match of abbreviated '-NonInteractive' command.
$NonInteractive = [Environment]::GetCommandLineArgs() | Where-Object{ $_ -like '-NonI*' }
if ([Environment]::UserInteractive -and -not $NonInteractive) {
# We are in an interactive shell.
return $false
}
return $true
}

Answer 2

You can check how powershell was called using Get-WmiObject for WMI objects:
(gwmi win32_process | ? { $_.processname -eq "powershell.exe" }) | select commandline
#commandline
#-----------
#"C:\WINDOWS\system32\WindowsPowerShell\v1.0\powershell.exe" -noprofile -NonInteractive
UPDATE: 2020-10-08
Starting in PowerShell 3.0, this cmdlet has been superseded by Get-CimInstance
(Get-CimInstance win32_process -Filter "ProcessID=$PID" | ? { $_.processname -eq "pwsh.exe" }) | select commandline
#commandline
#-----------
#"C:\Program Files\PowerShell\6\pwsh.exe"

Answer 3

I think the question needs a more thorough evaluation.
"interactive" means the shell is running as REPL - a continuous read-execute-print loop.
"non-interactive" means the shell is executing a script, command, or script block and terminates after execution.
If PowerShell is run with any of the options -Command, -EncodedCommand, or -File, it is non-interactive. Unfortunately, you can also run a script without options (pwsh script.ps1), so there is no bullet-proof way of detecting whether the shell is interactive.
So are we out of luck then? No, fortunately PowerShell does automatically add options that we can test if PowerShell runs a script block or is run via ssh to execute commands (ssh user#host command).
function IsInteractive {
# not including `-NonInteractive` since it apparently does nothing
# "Does not present an interactive prompt to the user" - no, it does present!
$non_interactive = '-command', '-c', '-encodedcommand', '-e', '-ec', '-file', '-f'
# alternatively `$non_interactive [-contains|-eq] $PSItem`
-not ([Environment]::GetCommandLineArgs() | Where-Object -FilterScript {$PSItem -in $non_interactive})
}
Now test in your PowerShell profile whether this is in interactive mode, so the profile is not run when you execute a script, command or script block (you still have to remember to run pwsh -f script.ps1 - not pwsh script.ps1)
if (-not (IsInteractive)) {
exit
}

Answer 4

Testing for interactivity should probably take both the process and the user into account. Looking for the -NonInteractive (minimally -noni) powershell switch to determine process interactivity (very similar to #VertigoRay's script) can be done using a simple filter with a lightweight -like condition:
function Test-Interactive
{
<#
.Synopsis
Determines whether both the user and process are interactive.
#>
[CmdletBinding()] Param()
[Environment]::UserInteractive -and
!([Environment]::GetCommandLineArgs() |? {$_ -ilike '-NonI*'})
}
This avoids the overhead of WMI, process exploration, imperative clutter, double negative naming, and even a full regex.

Answer 5

I wanted to put an updated answer here because it seems that [Environment]::UserInteractive doesn't behave the same between a .NET Core (container running microsoft/nanoserver) and .NET Full (container running microsoft/windowsservercore).
While [Environment]::UserInteractive will return True or False in 'regular' Windows, it will return $null in 'nanoserver'.
If you want a way to check interactive mode regardless of the value, add this check to your script:
($null -eq [Environment]::UserInteractive -or [Environment]::UserInteractive)
EDIT: To answer the comment of why not just check the truthiness, consider the following truth table that assumes such:
left | right | result
=======================
$null | $true | $false
$null | $false | $true (!) <--- not what you intended

Answer 6

This will return a Boolean when the -Noninteractive switch is used to launch the PowerShell prompt.
[Environment]::GetCommandLineArgs().Contains('-NonInteractive')

Answer 7

I came up with a posh port of existing and proven C# code that uses a fair bit of P/Invoke to determine all the corner cases. This code is used in my PowerShell Build Script that coordinates several build tasks around Visual Studio projects.
# Some code can be better expressed in C#...
#
Add-Type #'
using System;
using System.Runtime.InteropServices;
public class Utils
{
[DllImport("kernel32.dll")]
private static extern uint GetFileType(IntPtr hFile);
[DllImport("kernel32.dll")]
private static extern IntPtr GetStdHandle(int nStdHandle);
[DllImport("kernel32.dll")]
private static extern IntPtr GetConsoleWindow();
[DllImport("user32.dll")]
private static extern bool IsWindowVisible(IntPtr hWnd);
public static bool IsInteractiveAndVisible
{
get
{
return Environment.UserInteractive &&
GetConsoleWindow() != IntPtr.Zero &&
IsWindowVisible(GetConsoleWindow()) &&
GetFileType(GetStdHandle(-10)) == 2 && // STD_INPUT_HANDLE is FILE_TYPE_CHAR
GetFileType(GetStdHandle(-11)) == 2 && // STD_OUTPUT_HANDLE
GetFileType(GetStdHandle(-12)) == 2; // STD_ERROR_HANDLE
}
}
}
'#
# Use the interactivity check somewhere:
if (![Utils]::IsInteractiveAndVisible)
{
return
}

Answer 8

C:\> powershell -NoProfile -NoLogo -NonInteractive -Command "[Environment]::GetCommandLineArgs()"
C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe
-NoProfile
-NoLogo
-NonInteractive
-Command
[Environment]::GetCommandLineArgs()

Answer 9

Implement two scripts, one core.ps1 to be manually launched, and one scheduled.ps1 that launches core.ps1 with a parameter.

Answer 10

powerShell -NonInteractive { Get-WmiObject Win32_Process -Filter "Name like '%powershell%'" | select-Object CommandLine }
powershell -Command { Get-WmiObject Win32_Process -Filter "Name like '%powershell%'" | select-Object CommandLine }
In the first case, you'll get the "-NonInteractive" param. In the latter you won't.

Answer 11

Script: IsNonInteractive.ps1
function Test-IsNonInteractive()
{
#ref: http://www.powershellmagazine.com/2013/05/13/pstip-detecting-if-the-console-is-in-interactive-mode/
#powershell -NoProfile -NoLogo -NonInteractive -File .\IsNonInteractive.ps1
return [bool]([Environment]::GetCommandLineArgs() -Contains '-NonInteractive')
}
Test-IsNonInteractive
Example Usage (from command prompt)
pushd c:\My\Powershell\Scripts\Directory
::run in non-interactive mode
powershell -NoProfile -NoLogo -NonInteractive -File .\IsNonInteractive.ps1
::run in interactive mode
powershell -File .\IsNonInteractive.ps1
popd
More Involved Example Powershell Script
#script options
$promptForCredentialsInInteractive = $true
#script starts here
function Test-IsNonInteractive()
{
#ref: http://www.powershellmagazine.com/2013/05/13/pstip-detecting-if-the-console-is-in-interactive-mode/
#powershell -NoProfile -NoLogo -NonInteractive -File .\IsNonInteractive.ps1
return [bool]([Environment]::GetCommandLineArgs() -Contains '-NonInteractive')
}
function Get-CurrentUserCredentials()
{
return [System.Net.CredentialCache]::DefaultCredentials
}
function Get-CurrentUserName()
{
return ("{0}\{1}" -f $env:USERDOMAIN,$env:USERNAME)
}
$cred = $null
$user = Get-CurrentUserName
if (Test-IsNonInteractive)
{
$msg = 'non interactive'
$cred = Get-CurrentUserCredentials
}
else
{
$msg = 'interactive'
if ($promptForCredentialsInInteractive)
{
$cred = (get-credential -UserName $user -Message "Please enter the credentials you wish this script to use when accessing network resources")
$user = $cred.UserName
}
else
{
$cred = Get-CurrentUserCredentials
}
}
$msg = ("Running as user '{0}' in '{1}' mode" -f $user,$msg)
write-output $msg