Script to Rename Computer without Reboot

Rename.ps1

$ComputerName = "New Name"
   
Remove-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" -name "Hostname" 
Remove-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" -name "NV Hostname" 

Set-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Control\Computername\Computername" -name "Computername" -value $ComputerName
Set-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Control\Computername\ActiveComputername" -name "Computername" -value $ComputerName
Set-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" -name "Hostname" -value $ComputerName
Set-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" -name "NV Hostname" -value  $ComputerName
Set-ItemProperty -path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" -name "AltDefaultDomainName" -value $ComputerName
Set-ItemProperty -path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" -name "DefaultDomainName" -value $ComputerName

This breaks Powershell/other applications if the hostname is too long. For example, run it with $ComputerName = "hello.there.my.name.is.john" and then open another Powershell window; you'll find a cryptic error message. My guess is something is breaks in the registry.

@timnew Congratulations for this great script.

Can you please add some restrictions on the new name before actually applying the new name to windows, that is to say : forbid names containing . or spaces just like the warning printed by the netdom.exe tool :

The syntax of the new computer name, WORD1.WORD2
is incorrect. A computer name (DNS host label) may contain letters (a-z, A-Z),
numbers (0-9), and hyphens, but no spaces or periods (.).

The filename, directory name, or volume label syntax is incorrect.

The command failed to complete successfully.

@timnew The reboot might not be needed, but my question is : Do I need to kill all explorer.exe instances and relaunch one for the new registry key to be reloaded ?

i'm trying to rename my PC to its IP address this is what I have but i get an error saying the syntax of the command is incorrect

@echo off
SET /P < ipaddress >
REG ADD HKLM\SYSTEM\CurrentControlSet\Control\ComputerName\ComputerName /v ComputerName /t REG_SZ /d %PCNAME% /f

@echo off

set "cName=ROG-ISRA"
set "OEM=ROG STRIX B650E-F GAMING WIFI"

REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\OEMInformation" /t REG_SZ /v Model /d "%OEM%" /f

wmic computersystem where name="%computername%" call rename name="%cName%"

REG ADD "HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" /v "Hostname" /d %cName% /f
REG ADD "HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" /v "NV Hostname" /d  %cName% /f

set "sysSets=SystemSettings.exe"

tasklist /fi "ImageName eq %sysSets%" /fo csv 2>NUL | find /I "%sysSets%">NUL
if "%ERRORLEVEL%"=="0" (
	taskkill /F /IM %sysSets% 
	start ms-settings:
)

EDIT: More simply and best

FYI I had the issue that I needed a name change without reboot AND running PsExec for another user session on the same machine afterwards. I got this Error: Creating key file on $newComputername. The user name or password is incorrect / The network location cannot be reached.

Fix was to add the following lines to rename.ps1

# Restart service to have PsExec working after name change; wait 5 seconds to be safe
Restart-Service Server -Force
Start-Sleep