I tried some random parameters after the shutdown command in PowerShell 2.0 when I stumbled upon shutdown -y. All it seems to do is log out the user.
if any other random letter is used (that isn't a valid parameter) nothing happens. For example: shutdown -b
My question is: Does shutdown -y do anything special?
I could not find any documentation about this.
The Windows 2000 documentation states the following:
/y: Use this switch to force a "yes" answer to all queries from the computer.
So it looks like by using -y or /y with no other switches you are doing the default behaviour of shutdown.exe, which is to logoff the user while also forcing any confirm prompts to be acknowledged with yes.
Shutdown is not exactly a PowerShell command. It's the same shutdown.exe that also works in CMD.
Interestingly, the -y command is not mentioned in the documentation. As Mark Wragg found out, it's used to force a "yes" answer for remote shutdown. So, if no other parameters are specified, the default action (logoff user) is executed.
Another question: Why were you trying random parameters? Follow the docu and you're less likely to encounter any unexpected behavior.
来源：https://stackoverflow.com/questions/46071009/what-exactly-does-shutdown-y-do