How do I avoid getting data printed to stdout in my return value?

Here are a few different approaches for handling this:

• capture the output of the .cmd script:

  $output = & external.cmd # saves foo to $output so it isn't returned from the function

• redirect the output to null (throw it away)

  & external.cmd | Out-Null # throws stdout away

• redirect it to a file

  & external.cmd | Out-File filename.txt

• ignore it in the caller by skipping it in the array of objects that's returned from the function

  $val = aecho $val[1] #prints second object returned from function a (foo is object 1... $val[0])

In PowerShell, any output value your code does not capture is returned the caller (including stdout, stderr, etc). So you have to capture or pipe it to something that doesn't return a value, or you'll end up with an object[] as your return value from the function.

The return keyword is really just for clarity and immediate exit of a script block in PowerShell. Something like this would even work (not verbatim but just to give you the idea):

function foo(){    "a"    "b"    "c"}PS> $bar = fooPS> $bar.gettype()System.Object[]PS> $barabcfunction foobar(){    "a"    return "b"    "c"}PS> $myVar = foobarPS> $myVarab

I generally prefer to use one of the following two techniques which, in my opinion, make the code more readable:

• Cast an expression to void in order to suppress the return value:

  [void] (expression)

• Assign the output value to the $null variable:

  $null = expression

For example:

function foo{    # do some work    return "success"}function bar{    [void] (foo)  # no output    $null = foo   # no output    return "bar"}bar # outputs bar

If you want the output from the command to still print to the powershell command line, you can do a variant of the accepted answer:

& external.cmd | Out-Host