SeeUsing the Msg Command to Replace Net Sendfurther down the page.
It’s also available through the Command Prompt tool that’s accessible inAdvanced Startup OptionsandSystem Recovery Options.
The availability of certain msg command switches and other commandsyntaxmay differ from operating system to operating system.

you could save the output of the command to a file using aredirection operator.
SeeHow to Redirect Command Output to a Filefor general instructions or check out ourCommand Prompt Trickslist for more tips.
After entering amessagefor RODREGT, you’d press theEnterkey, thenCTRL+Z, thenEnteragain.
In the above example, we’re sending everyone connected to the server a test message [message].
Thiskeyis located in theWindows Registryunder theHKEY_LOCAL_MACHINEhive at this location:SYSTEM\CurrentControlSet\Control\Terminal Server.
Also, as mentioned a few times, this command is similar to the retired net send command.