What is `$?` in Powershell?

Question

What is the meaning of $? in Powershell?

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Edit: TechNet answers in tautology, without explaining what 'succeed' or 'fail' mean.

$?
Contains the execution status of the last operation. It contains TRUE if the last operation succeeded and FALSE if it failed.

I presumed $? would simply test whether $LastExitCode is 0, but I found a counter example where $? is False but $LastExitCode is True.

Answer 1

It returns true if the last command was successful, else false.

However, there are a number of caveats and non-obvious behaviour (e.g. what exactly is meant by "success"). I strongly recommend reading this article for a fuller treatment.

For example, consider calling Get-ChildItem.

PS> Get-ChildItem 

PS> $? 
    True

$? will return True as the call to Get-ChildItem succeeded.

However, if you call Get-ChildItem on a directory which does not exist it will return an error.

PS> Get-ChildItem SomeDirectoryWhichDoesNotExist
    Get-ChildItem : Cannot find path 'C:SomeDirectoryWhichDoesNotExist' because it does not exist.

PS> $?
    False

$? will return False here, as the previous command was not successful.