Powershell – Terminating a script in PowerShell

powershell

I've been looking for a way to terminate a PowerShell (PS1) script when an unrecoverable error occurs within a function. For example:

function foo() {
    # Do stuff that causes an error
    $host.Exit()
}

Of course there's no such thing as $host.Exit(). There is $host.SetShouldExit(), but this actually closes the console window, which is not what I want. What I need is something equivalent to Python's sys.exit() that will simply stop execution of the current script without further adieu.

Edit: Yeah, it's just exit. Duh.

Best Solution

I realize this is an old post but I find myself coming back to this thread a lot as it is one of the top search results when searching for this topic. However, I always leave more confused then when I came due to the conflicting information. Ultimately I always have to perform my own tests to figure it out. So this time I will post my findings.

TL;DR Most people will want to use Exit to terminate a running scripts. However, if your script is merely declaring functions to later be used in a shell, then you will want to use Return in the definitions of said functions.

Exit vs Return vs Break

  • Exit: This will "exit" the currently running context. If you call this command from a script it will exit the script. If you call this command from the shell it will exit the shell.

    If a function calls the Exit command it will exit what ever context it is running in. So if that function is only called from within a running script it will exit that script. However, if your script merely declares the function so that it can be used from the current shell and you run that function from the shell, it will exit the shell because the shell is the context in which the function contianing the Exit command is running.

    Note: By default if you right click on a script to run it in PowerShell, once the script is done running, PowerShell will close automatically. This has nothing to do with the Exit command or anything else in your script. It is just a default PowerShell behavior for scripts being ran using this specific method of running a script. The same is true for batch files and the Command Line window.

  • Return: This will return to the previous call point. If you call this command from a script (outside any functions) it will return to the shell. If you call this command from the shell it will return to the shell (which is the previous call point for a single command ran from the shell). If you call this command from a function it will return to where ever the function was called from.

    Execution of any commands after the call point that it is returned to will continue from that point. If a script is called from the shell and it contains the Return command outside any functions then when it returns to the shell there are no more commands to run thus making a Return used in this way essentially the same as Exit.

  • Break: This will break out of loops and switch cases. If you call this command while not in a loop or switch case it will break out of the script. If you call Break inside a loop that is nested inside a loop it will only break out of the loop it was called in.

    There is also an interesting feature of Break where you can prefix a loop with a label and then you can break out of that labeled loop even if the Break command is called within several nested groups within that labeled loop.

    While ($true) {
        # Code here will run
    
        :myLabel While ($true) {
            # Code here will run
    
            While ($true) {
                # Code here will run
    
                While ($true) {
                    # Code here will run
                    Break myLabel
                    # Code here will not run
                }
    
                # Code here will not run
            }
    
            # Code here will not run
        }
    
        # Code here will run
    }