How to modify name of computer or host

[Bret Busby]

Hello.

When the operating system is installed, the person installing the
operating system, can set or modify the default name for the
system/host.

I am wondering, when the operating system installation is completed,
and the system is in use, whether a superuser can modify the name of
the system/host, and, if so, how it is to be done, for example, at the
command line prompt, istead of having
BlackBox:~$
modifying it to be
BlackBox-Ubuntu14-04:~$

Years ago (about 20-30years ago), when I was being taught UNIX, I
remember being taught how to change the command prompt, so it could
include things such as a timestamp, etc, but, I believe that changing
the system/host name, would also change the syystem/host name for the
log in window when the screen is locked, and, in email headers, etc.

Thank you in anticipation.

Thank you in anticipation.

-- 
Bret Busby
Armadale
West Australia
..............

"So once you do know what the question actually is,
 you'll know what the answer means."
- Deep Thought,
 Chapter 28 of Book 1 of
 "The Hitchhiker's Guide to the Galaxy:
 A Trilogy In Four Parts",
 written by Douglas Adams,
 published by Pan Books, 1992

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