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Re: how do i simulate a null character from the keyboard?
- From: szeil at notesmail dot cs dot odu dot edu
- To: cygwin at cygwin dot com
- Cc: emallove at yahoo dot com
- Date: Thu, 21 Feb 2002 13:08:13 -0500
- Subject: Re: how do i simulate a null character from the keyboard?
- Reply-to: zeil at cs dot odu dot edu
Ethan Mallove <emallove at yahoo dot com> wrote:
> why is ctrl-d a logout command
>instead of NULL?
Because that's what ctrl-d is supposed to be for!
In the ASCII character code set, ctrl-d is defined as the EOT
signal, short for "End Of Transmission". So Unix (and
consequently Cygwin) were just following the published
NUL would, in general, be a terrible choice for an OS to
adopt because NUL characters have perfectly useful
applications in serial data streams (e.g., as something
that you can insert into a stream to affect the timing
without altering the message).
ctrl-z, by the way, used as the terminator by MSDOS and other
early PC operating systems was an unintentionally humorous
choice. It's defined as the SUB character, used as
a placeholder to indicate the data lost during a garbled transmission.
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