Redirecting output to $null in PowerShell, but ensuring the variable remains set

I'd prefer this way to redirect standard output (native PowerShell)...

($foo = someFunction) | out-null

But this works too:

($foo = someFunction) > $null

To redirect just standard error after defining $foo with result of "someFunction", do

($foo = someFunction) 2> $null

This is effectively the same as mentioned above.

Or to redirect any standard error messages from "someFunction" and then defining $foo with the result:

$foo = (someFunction 2> $null)

To redirect both you have a few options:

2>&1>$null
2>&1 | out-null

This should work.

 $foo = someFunction 2>$null

If it's errors you want to hide you can do it like this

$ErrorActionPreference = "SilentlyContinue"; #This will hide errors
$someObject.SomeFunction();
$ErrorActionPreference = "Continue"; #Turning errors back on

Warning messages should be written using the Write-Warning cmdlet, which allows the warning messages to be suppressed with the -WarningAction parameter or the $WarningPreference automatic variable. A function needs to use CmdletBinding to implement this feature.

function WarningTest {
    [CmdletBinding()]
    param($n)

    Write-Warning "This is a warning message for: $n."
    "Parameter n = $n"
}

$a = WarningTest 'test one' -WarningAction SilentlyContinue

# To turn off warnings for multiple commads,
# use the WarningPreference variable
$WarningPreference = 'SilentlyContinue'
$b = WarningTest 'test two'
$c = WarningTest 'test three'
# Turn messages back on.
$WarningPreference = 'Continue'
$c = WarningTest 'test four'

To make it shorter at the command prompt, you can use -wa 0:

PS> WarningTest 'parameter alias test' -wa 0

Write-Error, Write-Verbose and Write-Debug offer similar functionality for their corresponding types of messages.