How Do I Negate a Condition in Powershell?

Question

How do I negate a conditional test in PowerShell?

For example, if I want to check for the directory C:\Code, I can run:

if (Test-Path C:\Code){
  write "it exists!"
}

Is there a way to negate that condition, e.g. (non-working):

if (Not (Test-Path C:\Code)){
  write "it doesn't exist!"
}

Workaround:

if (Test-Path C:\Code){
}
else {
  write "it doesn't exist"
}

This works fine, but I'd prefer something inline.

Accepted Answer

You almost had it with Not. It should be:

if (-Not (Test-Path C:\Code)) {
    write "it doesn't exist!"
}

You can also use !: if (!(Test-Path C:\Code)){}

Just for fun, you could also use bitwise exclusive or, though it's not the most readable/understandable method.

if ((test-path C:\code) -bxor 1) {write "it doesn't exist!"}

Answer 2

If you are like me and dislike the double parenthesis, you can use a function

function not ($cm, $pm) {
  if (& $cm $pm) {0} else {1}
}

if (not Test-Path C:\Code) {'it does not exist!'}

Answer 3

Powershell also accept the C/C++/C* not operator

 if ( !(Test-Path C:\Code) ){ write "it doesn't exist!" }

I use it often because I'm used to C*...
allows code compression/simplification...
I also find it more elegant...

Answer 4

if you don't like the double brackets or you don't want to write a function, you can just use a variable.

$path = Test-Path C:\Code
if (!$path) {
    write "it doesn't exist!"
}

4 Answers