Re: how do emulators work

[Brian Dessent]

Christopher Spears wrote:

> This question may seem kind of basic but how do
> emulators work?  

Cygwin is not an emulator.  It's an implementation of the POSIX standard
functions and interfaces so that programs expecting to call those
functions can be compiled under windows.  It translates those function
calls into the equivalent Windows ones, with lots of glue logic to take
care of the fundamental differences between the two.  You might call
that "emulation" but it's not emulation in the traditional sense.  It's
similar to WINE, which is an implementation of the Win32 API under
linux.  WINE of course stands for "WINE is not an emulator".

> With UNIX, you have a program called
> the shell (csh, bash, etc.) that interprets commands
> and calls up different utilities (ls, cp, grep, etc.).

The same thing happens with Cygwin, it's no different.

>  However, cygwin sits inside Windows and is connected
> to windows.  For example, my home directory is
> /home/Christopher Spears/, which would never happen in
> UNIX because of the space in my name.  Is cygwin
> really UNIX or is it something different?

It's not traditional to have a home directory with a space in it under
most Unix variants but that's just tradition.  You could create a home
directory with a space in it with Linux if you really wanted to. 
Likewise, you could change your home directory in Cygwin to
/home/cspears.  Both systems support spaces in filenames and pathnames.

Brian

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Re: how do emulators work

[Igor Pechtchanski]

On Mon, 3 May 2004, Christopher Spears wrote:

> This question may seem kind of basic but how do emulators work?  With
> UNIX, you have a program called the shell (csh, bash, etc.) that
> interprets commands and calls up different utilities (ls, cp, grep,
> etc.).
>  However, cygwin sits inside Windows and is connected to windows.  For
> example, my home directory is /home/Christopher Spears/, which would
> never happen in UNIX because of the space in my name.  Is cygwin really
> UNIX or is it something different?
>
> -Chris

Firstly, .  That answers your last
question.  Besides, your premise is wrong: a space is a perfectly valid
character in Unix usernames, and nothing stops you from doing

$ useradd "Christopher Spears"

on Linux, with all the associated problems that Cygwin programs incur.
It's just that in Windows spaces in usernames and filenames are much more
common, and thus more visible.

FWIW, the shell in Cygwin behaves almost exactly like the shell in Unix
(because it is, for the most part, the same shell).

And, to answer your first, non-Cygwin-specific, question, try Googling for
'"how emulators work"'.
Igor
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