Question

You can exit PowerShell by typing exit. So far so good. But what exactly is this?

PS Home:\> gcm exit
Get-Command : The term 'exit' is not recognized as the name of a cmdlet, function, script file, or operable program. Ch
eck the spelling of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:4
+ gcm <<<<  exit
    + CategoryInfo          : ObjectNotFound: (exit:String) [Get-Command], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException,Microsoft.PowerShell.Commands.GetCommandCommand

So it’s neither a cmdlet, function, script or program. It leaves the question what exactly it is.

This unfortunately also means that one can’t create aliases to exit:

PS Home:\> New-Alias ^D exit
PS Home:\> ^D
Cannot resolve alias '♦' because it refers to term 'exit', which is not recognized as a cmdlet, function, operable prog
ram, or script file. Verify the term and try again.
At line:1 char:2
+ ♦ <<<<
    + CategoryInfo          : ObjectNotFound: (♦:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : AliasNotResolvedException

Are there any more such commands which are no commands?

ETA: Just for reference: I know I can simply wrap it into a function. My profile has the lines

# exit with Ctrl+D
iex "function $([char]4) { exit }"

in them. My question was just to know what exactly this command is.

Answer 1

It’s a reserved keyword (like return, filter, function, break).

Reference

Also, as per Section 7.6.4 of Bruce Payette’s Powershell in Action:

But what happens when you want a script to exit from within a function defined in that script? … To make this easier, Powershell has the exit keyword.

Of course, as other have pointed out, it’s not hard to do what you want by wrapping exit in a function:

PS C:\> function ex{exit}
PS C:\> new-alias ^D ex